R&D Highlights 2009

Dear reader,It is my pleasure and honour to present the Deltares report on the highlights of its research activities in 2009. More than 800 people are engaged at Deltares in high-grade research and consultancy in the field of delta issues. This research focuses on life, work and recreation in sustainable ways in low-lying, densely populated areas constituting the interface between land and sea: enabling delta life. This requires not only technical skills and a thorough knowledge of the functioning of the natural system and its response to human activities and environmental change, but also a broad interdisciplinary view of the functions of these systems and their value to society. I hope this report shows that Deltares and its partners are on the way to establishing that interdisciplinary approach.

I am proud to be able to present this collection of high-lights, which were produced in both subsidised research programmes and commissioned contract work. If a project description stirs your interest, please don’t hesitate to get in touch.

Huib de Vriend, Science Director

Foreword

Contents

Foreword 3

Deltares in the world 6R&D policy and issues 8

Facts and figures 11

Safety – living safely in the delta 18From river valley to mud flats area 20

Organic geochemical assessment of the onset of an

Oceanic Anoxic Event 22

Coastal modelling research with the USGS 24

Mud Model for Scheldt Estuary 26

Modelling sand bars in the Grand Canyon 28

OpenEarth 30

Flood Control 2015 32

Operational Satellite-Based Flood Mapping 34

Perception and risk communication when managing flood risks 36

Strength and Loading of Flood Defences 38

Full-scale piping experiment (SBW) 40

Development of DAM 42

A ship on the beach... 44

Healthy water and soil systems 46EXPOBASIN fit for purpose 48

Emission module – from emission data to water quality 50

Early Warning Against Scums 52

The origin of speciation 54

New methods for risk assessment: organisms are biotic ligands 56

Anaerobic benzene degradation in the presence of chlorate 58

Molecular detection tools for microbiologically influenced corrosion 60

Sustainable Use of Ecosystem Services 62

Availability of water and soil systems 64The implications of climate change for the IJsselmeer 66

Future flood risk in the Rhine basin 68

Groundwater age 70

PEAT-CO2: modelling water depth in Southeast Asian peatlands 72

The feasibility of Blue Energy 74

The “Waterverdeler”: serious gaming as a tool for providing a

broad public with complex knowledge 76

Living and building in the delta – lack of space 78Material Point Method for large deformations 80

Unstructured grid modelling 82

River groynes 84

Large-scale wave impacts 86

Scour – a recurring problem in the North Sea 88

Implementing risk management 90

DeltaBrain 92

Lateral loading of piles due to embankment construction 94

Compensation grouting in sand 96

Piled embankments 98

BioGrout 100

Integrated spatial development 102Bridging Boundaries 104

Integral spatial approach to coastal expansion opens up key issues 106

Modelling coastal vulnerability 108

Mitigating flood impact by splitting up polders 110

The morphological development of the Wadden Sea 112

Why wasn’t more knowledge getting through to the end user? A part of the answer to this “innovation paradox” is the way the knowledge infrastructure works. It was concluded that there should be a much more direct connection between knowledge institutes and the corporate sector, and that the latter needed to be encouraged to use new knowledge.

The 2009 R&D Annual ReportOne of the Deltares aims following on from this “connection” between the public and private sectors is to make R&D results more accessible. Many roads lead to Rome, and Deltares has numerous resources at its disposal for disseminating this knowledge: scientific publications, technical publications, reports, the website, wikis, communities of practice, courses and software. This R&D Highlights report for 2009 presents a selection of the R&D conducted in 2009 and it is structured on the lines of the social issues that are central to the Deltares mission. To enhance interactivity, one or more contact persons are listed for each project. People interested in more details should approach them.

A PDF version of these R&D Highlights 2009 can be downloaded from www.deltares.nl.

Deltares in the world

Deltares and its predecessors have been involved in R&D on Delta issues for more

than 80 years. There was an important transformation in 2003 when the government

found that too little fundamental research was being transformed into innovative

applications that move the Dutch knowledge economy forwards.

6 7

Demand-drivenIn the policy memorandum “Kennis voor de Samenleving” (Knowledge for Society, 2005), the government emphasises the need for a process of demand programming and financing for applied research at the Dutch knowledge institutes like Deltares. Demand programming ensures that there is more focus and quality in the research programmes and it results in a closer match between this research and strategic questions from government, the corporate sector and civil society. This is important to alleviate the innovation paradox and to enhance scientific research for society in general.

In the course of elaborating this ambition, the government gave strategic themes and social and innovation challenges a leading role in the research programmes. This focus on strategic themes should also extend the knowledge networks of the knowledge institutes, both at home and abroad. In essence, this results in a process in which the responsible ministries, in collaboration with the corporate sector, civil society and knowledge institutes, formulate the research issues within the parameters of the strategic themes.The research programmes are adapted accordingly and the government financing is linked to these research programmes. In 2006, the government formulated a number of strategic themes, including the associated social challenges or sub-themes, focusing expressly on the development of the technology and knowledge positions of the knowledge institutes, both within and across the themes.

In the new approach, the government directs the process of demand programming. The basic principle is that the process takes place interactively, with the demand side and financiers determining the knowledge and research issues. The issues are formulated in “knowledge arenas” that include the relevant stakeholders from the demand and supply sides. These arenas

R&D policy and issues

act as dynamic networks for an open innovation process. The corporate sector has a clear role in the process of demand programming. The government asks the corporate sector to participate actively in the knowledge arenas and, in that way, to make a contribution to steering the applied research financed by the government.

In order to secure the demand programming, the Ministry of Transport, Public Works and Water Management established a Council for Delta Research (Raad voor het Deltaonderzoek, RDO) with members from the government, knowledge institutes and the private sector. The council has defined the strategic knowledge and innovation issues with respect to water and subsoil in her Strategic Document (2009). The issues have been allocated to five themes:• Safety - Living safely in the delta• Healthy water and soil systems – Areas with quality• Availability of water and soil systems - Scarce resources• Living and building in the delta - Lack of space• Integrated spatial development The Deltares R&D programme has been organised along the lines of these five themes. The themes have been broken down further into research lines known as “road maps”.

Road mapsThe strategic social themes and issues in the themes are elaborated using what we call “road maps”. A road map is a way of planning the locations for the various projects in a research field. Research conducted outside Deltares can also play a role. There are two axes on road maps: the horizontal axis states the time (with a time horizon of a number of years); the vertical axis presents the type of research, evolving from fundamental research (usually at a university, for example in the form of doctoral research), passing on through strategic research and

8 9

applied research to actual, practical application. For Deltares, this last area means: products and services that are transferred to private parties (engineering firms or contractors) and/or that are necessary as support for the Ministry of Transport, Public Works and Water Management (through specialist consultancy or service level agreements). The routes set out in road maps make it clear how a particular subject can grow in the course of a few years into a “real” application and provide an answer to a knowledge or innovation question. They also make it clear whether, at any given moment, there is a reasonable mix of fundamental, strategic and applied research, and application in various processes. Fundamental developments dating back a number of years are cashed in and the seeds are planted for the applications of the future (a few years hence).

Facts and figures

Deltares brings knowledge about subsurface, soil and water systems together under a single roof. We use this knowledge in our own deltas and abroad. Translating science into solutions for delta-related issues is the core of the Deltares activities.

The yearly turnover of Deltares is about 100 M€, half of which is generated by R&D. The activities range from short- and long-term projects to targeted research, and include multidisciplinary policy and management studies. Deltares is also known for its unique experimental facilities and its powerful software, most of which is developed and validated in-house.

Advisory CouncilTo advise the management about the research programme and the strategic positioning of the research, Deltares established an external advisory council with representatives from the knowledge world and from the commercial sector. The issues dealt with by the advisory council are of a long-term nature. They include the question of where Deltares should invest to continue to fulfil its role, and which knowledge issues should be addressed in order to produce answers a few years hence.

The members of the advisory council are:• Professor Jacob Fokkema (chairman), Delft University of

Technology• Piet Besselink MSc, DHV Holding BV• Professor Rietje van Dam-Mieras, Leiden University• Professor Aad van der Horst, Delta Marine Consultants• Cees Slingerland MSc, Environmental Sciences Group,

Wageningen University and Research Centre• Arnold Steenbakker MSc, Fugro N.V.• Professor Marcel Stive, Delft University of Technology• Professor Bert van der Zwaan, Utrecht University

App

lication

Solutions

Produ

cts

Strateg

ican

dap

plied

research

2009 2010 2011 2012

Fund

.strat.

research

SO

TO/SLA

Market

models toolkit

guideline Deltadikes

Concept implementationDelta Committee recommendation

morphology

guideline/num. modelwave forms

wave forms

validation by measurements atextreme high water

guideline/ num. modelmorphology

Models toolkit

“Deltaplan”scenarioselaborated

PhD Ensemble simulations

Deltadike designscenario development

Roadmap Sustainable river

PhD17%

Scientific42%

Technical20%

Administrative20%

Number of employees 900 (850 full time equivalent)

Male74%

Female26%

Male/female ratio Deltares employees

10 11

• Hydraulic and geo-engineeringfoundation technology and underground construction hydro-engineering

• Social sciences and policy analysis risk management spatial scienceslife sciences and social sciences.

Cooperation with the universities is established through chairs and other appointments, and joint R&D projects conducted by PhD students. About 70 doctorate students are acquainted with Deltares in some way, as are 14 part-time professors and 14 university teachers. 19 doctorate students completed their dissertations in 2009.

Deltares works with universities to invest in knowledge centres at the universities of Delft, Utrecht, Twente and Wageningen. Current examples are the Geo-Engineering Knowledge Centre at Delft University of Technology, the Risk Management Knowledge Centre in conjunction with the University of Twente, the GeoSciences Knowledge Centre with Utrecht University and the Ground Knowledge Centre with Utrecht University and the Wageningen University and Research Centre.

Knowledge CentreBy implementing demand-driven programmes, Deltares invests in knowledge and technology in the area of water and the subsurface. The basis and the source for answers to knowledge issues is disciplinary knowledge. This basis must be maintained at an international standard. Together with universities, Deltares is investing in fundamental strategic research and networks of contacts in delta-technology disciplines.

Deltares focuses on water and the subsurface as systems, on measuring them, on civil engineering, and on human sciences. A large number of disciplines and sub-disciplines are relevant for the Deltares field of activities. The employees of Deltares, with their personal commitment to their own field of expertise, support the disciplinary framework. Deltares facilitates disciplinary activities in an organisational structure of seven disciplinary clusters, each of them co-chaired by a member of the scientific board and a Deltares knowledge manager.

• System informaticsmeasuring and monitoringmathematics and information technology

• Environmental sciences and engineeringchemistry and microbiologyecologyeco-engineering

• Geosciences and engineeringsoil mechanics and soil constructiongeology

• Hydro- and morphodynamics hydrodynamicssediment transport and morphology

• Hydrological scienceshydrologygeohydrology

Books (contributions)

41

Conference papers188Journal articles

125

Peer reviewed journal papers

40

Magazine articles

48

Publications

104 System Informatics

94 Environmental sciences and engineering

58 Geo sciences and engineering

122 Hydro- and morphodynamics

59 Hydrological sciences

49 Hydraulic and geo-engineering

74 Social sciences and policy analysis

Employees according to primary expertise

PhD-students by university

31 Del� University of Technology

9 Utrecht University

8 Twente University

6 VU University Amsterdam

5 Wageningen University and Research Center (WUR)

4 Unesco-IHE

6 Other (Netherlands)

3 Other (Abroad)

12 13

Scientific BoardThe Scientific Board plays an important role in terms of the function of Deltares as a knowledge centre. This Board consists of ten Deltares members of staff with international reputations who monitor the quality of the knowledge activities at Deltares and provide the management with advice – both upon request and at the Board’s own initiative – about the research programme, strategic investments, the discipline groups and the relationships with the universities. The members of the Scientific Board are:• Professor Frans Barends• Professor Eelco van Beek• Professor Marc Bierkens• Professor Remi Laane• Professor Arthur Mynett• Professor Huub Rijnaarts• Professor Dano Roelvink• Professor Frits van Tol • Dr. Rob Uittenbogaard• Professor Huib de Vriend

FacilitiesThe ability to break down natural processes into basic processes using a system approach, and to conduct relevant experiments, is needed if we are to meet demands for greater accuracy and reliability from society as a whole. So Deltares cannot fulfil its role as a knowledge institute without “cutting-edge” facilities. These facilities are: physical modelling installations, test sites in the field and numerical model systems. The research programme allocates budgets for research at and with these facilities.

GeoLab clusters facilities and expertise for research into soil and soil-related materials: laboratories for the advanced measurement of soil parameters, data-handling tools and

model-research facilities. The GeoCentrifuge is one of the largest geotechnical centrifuges in the world specialising in soft soils. These facilities are mainly used in the road maps of the themes “Building on and in soft soils” and “Safety of coastal, estuarine and riverine areas”.

HydroLab includes a cluster of facilities for research into water-related topics. The model research takes place in three halls (the saltwater/freshwater facility, the channels facility and the currents facility) and the Delta Flume. These hydraulic laboratories are used in the road maps in the core domains “Safety of coastal, estuarine and riverine areas”, “Water management and water usage” and “Hydraulic Engineering”. In 2009 a grant was awarded for a complete renewal of the Hydrolab facilities, culminating in a new Delta Flume at the Deltares premises in Delft.

MilieuLab includes a cluster of facilities for research into hydrochemistry-, geochemistry- and microbiology-related processes that are important for delta areas. The environmental facilities in Utrecht are shared with the University in Utrecht and TNO. These facilities are used in the road maps in the core domains “Water quality and aquatic ecology” and “Quality of soils and related materials”.

Field labsMeasurements in the field are, ultimately, the “proof of the pudding” for predictive calculations. Field laboratories are of pre-eminent importance in this respect and they are therefore the second cornerstone of the innovation triangle. The work here involves physical soil and water experiments monitored using geophysical measuring equipment in the field. Examples include experiments in dikes (the Smart Dike and the Live Dike), on the coast (Ecobeach), in surface water (Vlietlanden) and the sea (Eastern Scheldt). There are also chemical and microbiological

Geocentrifuge test IJkdijk

Delta Flume

Instrumentation at field lab

14 15

experiments in the field such as the encouragement of natural degradation processes at various remediation locations and experiments with SmartSoils innovations (strengthening dikes, sealing underground leaks).

ICT facilitiesThe third component of the facilities consists of the software development platforms with a shared architecture. This facility is vital for the development of new dynamic modelling methods and as a basis for a large number of applications. Software plays a key role in the dissemination of the very latest knowledge to a wide range of users. The Geosoftware Platform is used for the development of functionality in geomechanical and geotechnical software (in the well-known M series). The Hydrosoftware Platform is used for the development of hydrological, geohydrological and hydraulic software: Delft3D, Sobek, Modflow. The Environmental Software Platform is the place where we develop Delwaq.

New knowledge acquired during disciplinary research and in various road maps is transformed as much as possible into new functionality for software on the platforms. GeoBrain/DeltaBrain, finally, combines a range of knowledge sources in the shape of expertise (data, models) with knowledge based on experience. The unique combination of “hard” (objective) measurements and computer models and “soft” (subjective) experience and expert knowledge makes, with adaptations for particular applications, a contribution to risk management and decision support for delta issues. It constitutes the virtual and life-long learning and working environment for present and future generations of delta engineers. GeoBrain is the part of DeltaBrain that focuses on geo-engineering and there is already a range of applications here.

16 17

backgroundProtection against floods is the day-to-day, ongoing and primary concern of us all. The issue, too, is how to maintain safety in this area in the long term, particularly taking into account increasing socio-economic pressure on the available space and the capital invested in this country. Water safety and spatial quality in our country require answers at a range of temporal and spatial scales.

In the past, water safety policies in the Netherlands have been based primarily on the construction of water defences: structures to limit the risk of flooding, even at extremely high water levels. This approach makes it essential to assess the quality of the defence structures and to understand the associated failure mechanisms in dikes. It is characterised by the restricted spatial and time scales.

More and more, attention is focusing on the combination of both flooding probability and secondary damage: the flood risk.

scopeThe low altitude of the Netherlands means that protection against flooding is a

permanent concern. Soil subsidence and climate change are exacerbating the

problem. In addition, we are making more and more demands on the spatial quality of

the country. Smart dikes, improvements in our understanding of the real strength of,

and loads on, the dikes, the relaxation of restrictions on water flows, warning systems

and non-technical alternatives in the eventuality that things go wrong after all: these

things make up the heart of the research programme.

So water safety cannot be dissociated from spatial and socio-economic developments in the hinterland. Requirements in the area of water defences, water management, the economy, transport, nature, recreation and housing demand a coherent, integrated approach. This amounts to a more large-scale approach in both space and time.

The ongoing increase in the flow of data does not make decision-making easier, especially when a calamity is imminent. Further development of the general tools and techniques used in operational flood forecasting systems for rivers and coastal systems is needed to improve the quality of the forecasts. Improvements in the quality of flood forecasting should lead to better risk analysis (e.g. dike strength) and improved adaptation times in relation to protection strategies and emergency measures.

In the coastal zone, sand is the vital functional element. The current coastal management policy uses replenishment to keep the amount of sand in the coastal area up to standard, maintaining or even enhancing safety in a natural way, and responding to the consequences of rising sea levels sustainably and flexibly.

The road maps in this core domain are New standardisation, Real-time flood risk management, Coastal systems behaviour, System tools for preparation and response and Innovative design concepts for water defences.

18 19

Safety – living safely in the delta

Further reading• M. Hijma & K.Cohen, Timing

and magnitude of the sea-level jump preluding the 8200 yr event. Geology 38 (2010) 275-278

• M.P. Hijma, From river valley to estuary: the early-mid Holocene transgression of the Rhine-Meuse valley, PhD-thesis, Utrecht University 2009

From river valley to mud

flats area

Research carried out by Utrecht University, Deltares and TNO shows that, between 8500 and 8300 years ago, the sea level around the Netherlands rose by 2 m per century. The sea level at that time was calculated by dating the deep-lying submerged layers of peat in the Rotterdam area. The study has important implications in light of the rapid rate of sea level rise expected in coming centuries.

The rapid rate of sea level rise was primarily the result of the sudden collapse of ice dams in North America, behind which large glacial lakes had formed. As a result, the sea level rose rapidly, the North Atlantic became less salty and the warm Gulf Stream was interrupted. This was followed by a cold period around 8200 years ago, which is known as ’the 8.2 event’. We measured a total rise of 4 ± 0.5 m in roughly two centuries. We could split this rise in two: 2 m of the rise would have occurred anyway due to steady melting of the ice sheets, but the remaining 2 m is directly linked to the drainage events in North America.

m.p.hijma@arch.leidenuniv.nl+31 (0)71 527 1680

kim.cohen@deltares.nl+31 (0)88 335 7820

This research is important because it reveals the volume of water which entered the North Atlantic with the draining of the glacial lakes. Climate models will now be able to more effectively reproduce the 8.2 event, and it will be much easier to test the sensitivity of the warm Gulf Stream to an increased volume of freshwater. In the near future, there is a chance the North Atlantic could again become less salty due to the increased rate at which the Greenland ice cap is melting. In theory, this could again interrupt the warm Gulf Stream or cause it to become less powerful, resulting in a very cold period, primarily in North-West Europe. In response to this theory, climate models are being implemented to determine whether this will in fact occur. The new results will increase the reliability of the scenario predictions.The rapid rate of sea level rise left the Netherlands submerged in a fairly short period of time. Before 8500 years ago, the landscape around Rotterdam was characterised by a river valley. However, 500 years later, this had completely changed and the entire area consisted largely of mud flats, comparable to the Wadden Sea area nowadays, through which the Rhine and Meuse rivers flowed. The submersion of the western region of the Netherlands between 10000 and 6000 years ago has been described in detail in a PhD thesis.

Example of the studied sediment.

The organic layer in the middle of the

picture was formed just before the

drowning occurred

Riverbed dug out by the sudden

draining of glacial Lake Agassiz,

about 10.000 years ago (Photo:

Jim Brekke at www.flickr.com)

Study area

Contact:

20 21

Organic geochemical

assessment of the onset of

an Oceanic Anoxic Event

During the Jurassic, abrupt global warming of between 5 and 10˚C was associated with severe environmental change. Many organisms became extinct and the global carbon cycle was thrown off-balance. One of the most intriguing effects was that the oxygen content of the oceans was drastically reduced. These intervals of reduced oxygen content are now known as oceanic anoxic events (OAE). OAEs are associated with periods of global warming and have occurred a few times in the history of the Earth. In the current study the focus is specifically on the Toarcian OAE, a well-documented OAE from the early Jurassic (~183 Ma). In the Netherlands, the associated organic-rich black sediments are known as the Posidonia Shale, the most important oil source rock in the Netherlands.

A geochemical study was conducted on a cored Posidonia Shale section and underlying sediments from a well located in the southern North Sea offshore the Netherlands. Abhinav Sing Gill (Utrecht University) carried out some of this study as part of a Master’s thesis.Samples were subjected to a variety of analytical techniques, including total carbon and sulphur (CS) analysis, rock eval pyrolysis, gas chromatography-mass spectrometry and carbon and sulphur isotope analysis. Furthermore, detailed organic geochemical studies have recently revealed the presence of molecules (“biomarkers”) that derive from green sulphur bacteria, organisms that required both light and free hydrogen sulphide (H2S), demonstrating that these anoxic conditions extended high into the upper water column.

Our data provides evidence that the establishment of these anoxic conditions is a gradual process: from sediment anoxic conditions in the ‘proto OAE’ into true anoxia within the Posidonia Shale. This is indicated by the depth profile of most of the measured parameters. The values gradually increase in

harry.veld@deltares.nl +31 (0)88 335 7161

the underlying sediments with decreasing depth towards the Posidonia Shale. Within the Posidonia Shale the values of those parameters remain constant.Another important event during the Toarcian was the negative shift in the carbon isotope values of 13C. The typical value of the carbon isotope ratio 13C/ 12C of marine organic matter deviates strongly in the black shale facies of the Posidonia Shale. The cause of this shift has been a matter of intense debate and many hypotheses have been formulated for its explanation, but this remains an open question. Most of the sections containing the Posidonia Shale record this shift. This confirms that the OAE may have been a global event.

Our current research focuses on, among other things, the question of whether the ‘proto OAE’ development can be recognised throughout the basin.

Further readingAbhinav Sing Gill, Organic geochemical assessment of the Posidonia shale in the Netherlands, Master’s Thesis, Utrecht University, 2007

Contact:

Distribution of the Posidonia

Shale in the subsurface of

the Netherlands

22 23

SR

QP

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NMLKJ

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Coastal modelling research

with the USGS

Since 2002, Deltares and the US Geological Survey (USGS) have been collaborating on coastal morphodynamic research. The present USGS cooperative agreement is linked to the Coastal and Marine Geology Program that is operated from science centres in Santa Cruz/Menlo Park (California), St. Petersburg (Florida) and Woods Hole (Massachusetts).

The overall purpose of the collaboration is to provide mutual benefits in coastal morphodynamic modelling in the broadest sense. Research topics include various coastal modelling studies such as sediment transport and morphological evolution in the Columbia River littoral cell, coastal hazards along the California Coast, the impact of extreme events such as hurricanes and tsunamis, and the effects of vegetation on hydrodynamics and sediment transport.

Broadly speaking, the USGS possesses the necessary data, while Deltares can supply the modelling software and expertise. The many types of data are used to validate the numerical models to provide a better understanding of the natural system and

johan.boon@deltares.nl +31 (0)88 335 8536

eelias@usgs.gov

anticipated long-term processes like sea level rise, and the consequences of human interventions like sand nourishment offshore or in gullies. In the last few years, the collaboration greatly benefited from student exchanges at the MSc and PhD levels in close conjunction with Delft University and UNESCO-IHE.

One of the joint studies included in the collaboration is the Multi-Hazards Demonstration Project in Southern California. The USGS is leading the development of a modelling system for forecasting the impact of winter storms threatening the entire Southern California shoreline from Point Conception to the US-Mexican border. The modelling system, which runs in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable the detailed prediction of currents, wave height, wave run-up, and total water levels. Additional research-grade predictions of coastal flooding, inundation, erosion, and cliff failure will be performed. Initial model testing, performance evaluation, and product development are focused on coastal-hazard hindcasts of selected historical winter storms, as well as additional severe winter-storm simulations based on statistical analyses of historical wave and water-level data. The coastal-hazards model design will also be appropriate for simulating the impact of storms in various sea level rise and climate-change scenarios.

Contact:

Screen dump from the coastal hazard

operational framework

Overview of nested model in the

operational model framework

24 25

Mud Model for

Scheldt Estuary

The Scheldt estuary in the southwest of the Netherlands and in Belgium is tide-dominated. The estuary includes the entire gradient from fresh- to saltwater areas and it provides various habitats for marine flora and fauna. In addition to these ecological values, the estuary is of major economic importance as it provides navigation routes to the ports of Antwerp, Gent, Terneuzen and Vlissingen. The frequent conflicts between economic and environmental interests make the management of the estuary a complex task, leading to exceptional collaboration between the Dutch and Belgium governments. This resulted in the formulation of a Long-Term Vision (LTV) for the Scheldt estuary.

The LTV includes a bilateral agreement for joint fact-finding in a shared monitoring and research programme that started in 2005. The research programme focuses on the three goals of the LTV: safety, ecology and accessibility. It is conducted by Dutch and Flemish institutes working in concert, with Deltares as the principal representative of the Netherlands.

Under the LTV, ‘accessibility’ research has been ongoing since 2006 to understand the fine-sediment dynamics of the estuary. Turbidity affects ecological productivity and functioning, and harbour and fairway maintenance. It also has an aesthetic impact. The main result of this work has been a fine-sediment transport model for the Scheldt estuary. The model includes most of our present system understanding. Forcing factors such as tide, wind, waves and river discharge have all been included, either in schematised form or in full detail. A simulation period of up to one year is feasible, allowing for the inclusion of seasonal dynamics.

This model has been used to simulate a number of scenarios, including the deepening of the fairway, the extension of harbour basins and changes in dredging policy. One of the scenario

thijs.vankessel@deltares.nl+31 (0)88 335 8239

studies focused on maximum turbidity levels near Zeebrugge at the Scheldt estuary and at Antwerp. These maximum levels were reproduced by the model and it was confirmed that these are natural features of the estuary and therefore not the result of dredging activities. Harbour maintenance does, however, cause human-induced turbidity fluctuations (both positive and negative).

The scenario studies also show that anthropogenic fluctuations are small compared to the natural ones near Vlissingen and Terneuzen. Siltation flux in these harbours is small compared to the large fine-sediment flux through the estuary. Near Antwerp, anthropogenic fluctuations become more significant as the estuary narrows and the natural flux decreases.

Further work in 2010 includes the analysis of the harbour maintenance strategy at Zeebrugge and Antwerp and the continuation of remote sensing work to validate the spatial sediment distribution computed by the model. There is an important link with the research being conducted for the LTV ecology goal. The output of the fine-sediment model serves as input for the ecological model, which is still under construction.

Further reading• Scheldemonitor

(www.scheldemonitor.be)• Partners: Flanders

Hydraulics, IVM, NIOO

FinanceTO Directie Zeeland,Waterdienst

Average mud concentration

(mg/l) in the Scheldt, 1 October

– 31 December 2006

Contact:

26 27

Salinity (upper panel) and mud

concentration (lower panel) in

thalweg on 23/10/2006 8:00u

between Vlissingen (0 km) and

Rupelmonde (105 km)

Modelling sand bars in

the Grand Canyon

Predicting bed topography changes in situations with complex 3D flow fields is still virgin territory in river engineering. The recent developments in the Delft3D software have supplied a powerful tool for simulating the relevant processes. Relevant potential applications of this tool are bed topography in eddy zones in groyne fields, and the morphological impacts of groyne adaptations for flood protection targets. The tool can also be used to study bar development caused by horizontal eddies and separation in sharp bends or off-takes (river bifurcations or side channels). However, the lack of experience with this relative ‘immature’ tool argues against operational use pending more thorough validation.

Against this background, Deltares is working with the US Geological Survey (USGS) river groups in Flagstaff, Sacramento and Golden in the USA to model sand bars in the Colorado River in the Grand Canyon. After successful cooperation on coastal morphology studies, the USGS decided in 2007 to extend this cooperation to the river application in the Grand Canyon. The USGS needs process-based modelling tools for sand management in this river. The construction of the Glen Canyon dam in 1963 upstream of Grand Canyon National Park cut off the sand supply to the river. This is leading to the disappearance of the sand bars that serve as a habitat for endangered fish, as camping grounds for hikers and rafters, and as sand coverage for archaeological sites. These bars are mostly located in the complex eddies that develop downstream of riffles. As part of a US environmental programme for sand-bar restoration, high-discharge releases from the dam are created during high sand inflow from tributaries in order to get sand on the bars. To design optimal dam releases, it is necessary, among other things, to accurately predict the building-up of the bars. The 3D flow and morphology of Delft3D have been used for this purpose.

kees.sloff@deltares.nl +31 (0)88 335 8152

The focus of this study is the validation of the present features in Delft3D for 3D high-resolution modelling, and the implementation of improvements that do not require a full redesign of concepts or theory. In 2008, eddies and bar development at Mile 45 were monitored extensively during a high-flow release. The comparison of model simulations and survey data show that the 3D turbulent flow structure in the pools can be reproduced satisfactorily. The observed development of the bars is also reproduced qualitatively, but sensitivity to the components of transport models and sediment conditions, and some missing processes (such as slumping) make more in-depth studies necessary. The study is being continued with more simulations and thorough analysis by the USGS Geomorphology and Sediment Transport Laboratory, and improvements to the concepts by Deltares. Further reading

Sloff, C.J., S. Wright and M. Kaplinski (2009) High resolution three dimensional modeling of river eddy sandbars, Grand Canyon, U.S.A, 6th IAHR Symposium RCEM 2009

Contact:

28 29

OpenEarth

The sustainable interaction between mankind and Planet Earth poses huge hydraulic and environmental engineering challenges. The paradigm to confront these challenges – one-project-at-a-time – is apparently attractive from a budget management perspective, but it results in serious inefficiencies in terms of developing and archiving the basic elements that are invariably involved: data, models and tools. Hardly any project is, in itself, of sufficient scale to develop easily accessible and high-quality data archives, state-of-the-art modelling systems and well-tested analysis tools under version control.

Research and consultancy projects commonly spend a significant part of their budget on setting up some basic infrastructure, most of which dissipates again once the project is finished. Deltares, TU Delft and Unesco-IHE have therefore developed the OpenEarth framework (www.openearth.eu). OpenEarth is an up-and-running, open-source initiative for archiving, hosting and disseminating Data, Models and Tools for marine & coastal scientists and engineers. This system aims to remedy the inefficiencies described here by adopting an approach transcending individual projects.

OpenEarth services are built from existing, proven, open-source technology elements. We adhere to international standards as much as possible (NASA standards, for example). For the purposes of data storage, OpenEarth is collaborating with the TU Delft library with the aim of, for instance, assigning digital object identifiers (doi) to data on the lines of their assignation to scientific papers (on-line or paper). This allows most of the budget to be spent where it is most desperately needed: communication, training and documentation. Most importantly, it will allow the budget to be allocated to a lobby with the aim of changing the paradigm in favour of the open-source sharing of data models and tools. An important element is the organisation of regular sprint sessions

gerben.deboer@deltares.nl+31 (0)88 335 8534

fedor.baart@deltares.nl+31 (0)88 335 8140

to exchange ideas in association with immediate hands-on application.

OpenEarth provides three web-service levels for data. First, raw data are safeguarded in repositories with version control, with all the processing tools being conveniently stored alongside the data. Second, the data are made available on the web as netCDF files (www.opendap.deltares.nl). The novel OPeNDAP technology allows OpenEarth to share an enormous amount of data on the web, allowing users not only to request all meta-information, but to have direct access to the particular slice they need. Third, all data are offered as pre-visualised Google EarthTM feeds using the very same network-linked-tiled-image principle that Google EarthTM uses itself to deliver all aerial photos. With OpenEarth’s Google EarthTM feeds it is now possible to hover seamlessly from 5m resolution dune data to 50km weather model results at your own desktop. This is unprecedented: all the world’s data is at your fingertips. You are cordially invited to join in, for free.

Further readinghttp://www.openearth.eu

FinanceBuilding with Nature, EU FP 7 MICORE, Delft Cluster, Kustlijnzorg and multiple other projects/consortia supporting in kind (data, models, tools) by adopting the OpenEarth framework

Contact:

Delft-3D simulation KatrinaZeeland surface contours from AHN

and depth soundings (RWS)

Dutch coastline with sand

nourishment database (RWS)

Temperature distribution North Sea

(KNMI-NIOO)

All figures created with Google

EarthTM mapping services

30 31

Flood Control 2015

The Flood Control 2015 innovation programme aims to support decision-making during flooding (imminent or actual). The integration of information about water levels, dike strength and the consequences of flooding is crucial for effective and efficient decision-making. In addition to more safety through better risk management, FC2015 also aims to enhance export opportunities for Dutch business and to interest more young people in civil engineering. The four cornerstones of the FC2015 programme are: more and better quality information about water systems, improved forecasting systems, support for decision-makers, and modular ICT systems that link those components. The Deltares focus in the programme is on dike monitoring, dike strength forecasting, hydrological forecasting, dealing with uncertainties, and the integration of forecasting systems and training for end users.

Robust monitoring systems for dike strength and forecasting contribute to the improvement of flood risk management. Deltares, IBM and TNO have built a prototype system for multiple sensor-based dike monitoring and dike stability forecasting. The sensor network design includes a mechanism that calculates the necessary information from nearby or alternative sensors when the primary system has failed for any reason. This flexibility makes this a suitable solution for a dike monitoring platform and

karel.heynert@deltares.nl +31 (0)88 335 8488

pauline.kruiver@deltares.nl +31 (0)88 335 7859

is therefore the next step towards large-scale dike monitoring using sensors. The system is in experimentally use at the Smart Dike and Live Dike testing sites in the Netherlands. As a part of this study, the numerical models for dike strength analysis have been adapted to handle real-time sensor data.

The Demonstrator Flood Control Room (DFCR) project is developing a powerful research platform – hardware, software architecture and experimental control room – that integrates the various products of the Flood Control 2015 programme, testing and demonstrating them together. This strengthens the links between the various projects, accelerating and structuring the innovation process. An additional component of this project is the development of an open architecture for flood control systems. IBM and Deltares are working together on this innovation process.A DFCR was set up at Deltares in Delft in 2009. Operational monitoring, forecasting and decision support systems and FC2015 innovations are accessible through the DFCR, and they can be tested and used side by side. A series of workshops with stakeholders and research partners were organised in the DFCR to evaluate research products and focus the FC2015 programme. The DFCR project will proceed in 2010 with an additional focus on the effective facilitation of training and serious gaming. Other FC2015 projects have been described elsewhere in this publication: Dike Analysis Module, Smart Dike Piping, and rapid and operational flood mapping using satellites.

Further readinghttp://www.floodcontrol2015.com

FinanceThe Flood Control 2015 research programme is an initiative of Arcadis, Fugro, HKV, Royal Haskoning, IBM, TNO, ITC, the IJkdijk Foundation and Deltares. The innovation programme will run from 2008 to 2012 and it has a budget of € 20 million. All projects are multi-party endeavours

Contact:

Demonstrator Flood Control Room

in Delft

32 33

Operational Satellite-Based

Flood Mapping

Governments in areas with regular flooding need reliable data to ensure good flood forecasting and therefore a safer living environment. They need these data in a form they can understand and that they can use in decision-making and in emergency management in particular. Operational systems must make this connection between raw data and useful information. When floods are imminent, there is always a shortage of hard hydrological data about, for example, water levels or rainfall. In addition, in remote areas in the world, there is usually no real-time information about flood extent, and this hampers efficient mitigation action.

The idea behind the Operational Satellite-Based Flood Mapping project is to connect near-real-time flood information as measured by satellites to maps that can be used by water managers for mitigating action, but also by forecasters/modellers to improve existing flood forecasting systems.

Images from Synthetic Aperture Radar (SAR) satellites provide good contrast between land and water at a resolution of 10-1000 metres. Most satellites provide global coverage every three days

rogier.westerhoff@deltares.nl +31 (0)88 335 7175

marco.kleuskens@deltares.nl +31 (0)88 335 7855

regardless of the weather conditions or time of day. The accuracy in space and time can be improved by combining images of more SAR satellites and other instruments such as multi-spectral imaging and radar altimetry. In addition, the European Sentinel satellites from the European Space Agency (the first one of which will be launched in 2011) will improve the spatial and temporal resolution that is needed for operational flood information for high-resolution use, as in the UK and the Netherlands.

To combine different sources, satellite information has to be processed objectively. Previous research has transformed radar images into discrete flood extents using pre-defined thresholds, making the information valid for one satellite only in one condition. By contrast, this approach calculates flood probabilities and uses the images themselves to train the algorithm. In this way, all datasets can be treated in the same way. When different datasets are combined, the reliability of each dataset is taken into account. In combination with a satellite topography map and altimetry measurements for water, the result can be further improved.

The Mekong Delta and Tonle Sap Lake in Southeast Asia were used as test areas, because this region is flooded every year. As a lot of the Mekong area is situated in remote areas, flood extent maps are a welcome addition to existing hydrological information. They can be delivered on an operational basis by combining information and displaying them in the Deltares FEWS system.

Contact:

Tonle Sap lake (Photograph: NGM)

SAR image of the Mekong delta with a

resolution of 500 metres. The image

was taken by ENVISAT (Courtesy of

ESA)

Flood-related satellite products

in FEWS. Left: a combined flood

probability map based on ENVISAT

SAR images. Right: a topography

map generated by the Shuttle Radar

Topography Mission (SRTM)

34 35

Perception and risk

communication when

managing flood risks

The PROMO research project looked at perception and communication relating to flood risks. The project included three different research components: a socio-psychological, a socio-economic and an institutional component. The socio-psychological component examined the determinants of risk perception, the intentions of the public to prepare for flooding and the effectiveness of risk communication in terms of raising risk awareness. The socio-economic component focused on the economic aspects of risk perception, including the willingness of households to pay for flood risk reduction. The institutional component addressed the perspectives for, and possible obstacles to, the implementation of a risk-based water-safety policy.

The project included extensive surveys of how approximately 1500 households perceived risks. The households were located in different dike rings areas: the coastal dike rings of Zeeland (28, 29 and 30), the dike ring 36 along the river Meuse and the dike ring 22, Isle of Dordrecht in the Lower Rivers region. These dike rings differ in terms of their flood protection level. The surveys included various questions relating to risk perception and people’s attitudes to different preparatory measures, such as looking for emergency information, acquiring an emergency kit, making appointments with family and neighbours or purchasing insurance. The intentional behaviour of the public was analysed by applying and extending the Protective Action Decision Model developed by Lindell & Perry.

The research shows the average Dutch citizen perceives risks as being low/very low, and that the Dutch public has little intention to make preparations for flooding. Looking for emergency information was considered the most effective preparatory measure. Even so, only about 30% of the respondents said they would be looking for such information in the near

herman.vandermost@deltares.nl +31 (0)88 335 8570

future. The project also looked at different approaches to risk communication. The current generic approach was found to be ineffective. To be effective, risk communication should focus on the local flood risk, response efficacy and the self-efficacy of possible preparatory measures. Experiments with a local tailor-made approach of this kind indicate that it is a promising way of achieving more effective risk communication.

The socio-economic component also investigated to what extent flood risk plays a role in the location/re-location of industry. A survey of some 200 Dutch companies made it clear that flood risk hardly plays a role in location decisions. Open interviews, however, suggest that perceived flood risk may play a role in the decisions of some foreign companies.

Further readingT. Terpstra, Flood Preparedness. Thoughts, Feelings and Intentions of the Dutch Public. PhD thesis, University of Twente, 2009

Finance• Leven met Water• DG-Water• Ministry of the Interior and

Kingdom relations• STOWA• province Zuid-Holland • province Zeeland

Cooperation• Deltares• University Twente• TU Delft• ITC• TNO• HKV Lijn in Water

Contact:

36 37

Strength and Loading of

Flood Defences

Almost 3,500 kilometres of Dutch dunes and dikes along the coast, estuaries and rivers have to be assessed every five years to check whether they meet statutory safety standards. The assessments clarify which flood defence structures require improvements. The social, political and economic interests are enormous.

Dikes and dunes must be able to withstand extreme water levels and wave conditions. Compulsory safety assessments started in 1996 but they have not yet been completely successful. Predicting extreme conditions still involves too many uncertainties, while some specific dike failure mechanisms cannot be described accurately enough. The Strength and Loading of Flood Defences Programme involves the research needed to fill in the knowledge gaps and to help improve the safety assessments. Universities, institutes and consultants worldwide are involved in the programme.

The research projects in the programme focus on both flood defence loads and strength. The Ministry of Transport, Public Works and Water Management conducted an extensive campaign measuring waves and currents. Improvements to the model for

frans.hamer@deltares.nl+31 (0)88 335 8093

wave prediction were successfully validated with the measured data (hindcasts). We can now predict extreme wave conditions more reliably, even for the complex geography of the Wadden Sea in the north of the Netherlands.

To determine the strength of flood defence structures, possible failure mechanisms need to be identified. First of all, of course, dikes need to be high enough to prevent too much wave overtopping. Wave overtopping can lead to the erosion of the inner slope of the dike, and possibly to the collapse of the entire structure. Extensive studies of the resistance of grass revetments subjected to wave overtopping and full size field tests at several dike locations in the Netherlands produced impressive results. The grass revetments appeared to be much more resistant to erosion by wave overtopping than was previously believed. However, transition zones or construction elements in the dike proved to be weak spots.

Other projects in the Strength and Loading of Flood Defences Programme also helped to reduce uncertainties in dike assessment. Piping studies are described in a separate highlight in this report. A guide for the schematisation of the subsoil based on soil investigations will help work to become more consistent and uniform. Progress has been made on producing better estimates of the macro-stability of flood defence structures. Instruments are being improved to assess dune erosion properly.

FundingThe Strength and Loading of Flood Defences Programme (Dutch title: “Sterkte & Belastingen Waterkeringen”) has been assigned by the Ministry of Transport, Public Works and Water Management in The Netherlands

Contact:

Extreme storm simulated by a wave-

overtopping simulator

Field test set up at the Afsluitdijk

Wave measuring buoys and

measurement posts in the complex

geometry of the Wadden Sea

38 39

Full-scale piping experiment

(SBW)

Piping, the process of retrograde erosion in sandy layers below clay dikes, is seen as an important failure mechanism in water-retaining structures in the Netherlands. Several computation models are available for estimating the potential occurrence of piping. The most widely-used models in the Netherlands are the empirical relation of Bligh (1910) and the semi-analytical model of Sellmeijer (1988), which describes the piping process in a more complete way.

The Sellmeijer model is based on the equilibrium of the forces of sand grains, flow in the developing channel (pipe) and flow through the aquifer. The model states the relation between pipe length and hydraulic head at which the sand grains are in equilibrium. Below the critical head the channel will stabilise.

We drew on a series of small-scale, medium-scale and centrifuge experiments to refine the Sellmeijer calculation model. Four full-scale tests were conducted to validate different aspects of the calculation model. The full-scale experiment was performed at the Smart Dike location in the north-east of the Netherlands.

ulrich.forster@deltares.nl+31 (0)88 335 7203

vera.vanbeek@deltares.nl+31 (0)88 335 7228

andre.koelewijn@deltares.nl+31 (0)88 335 7338

Two large basins were created, filled with two types of sand (coarse and fine). A clay dike was built with a height of 3.5 m, slopes of 1:2 and a seepage length of 15 m was built on top of the homogeneously densified and well-saturated sand layer.

At the sand-clay interface, several rows of pore pressure meters monitored pipe formation. In addition, fibre optics at the interface measured temperature and strain differences. Two of the four experiments tested additional monitoring equipment.

On the basis of the observations in the full-scale experiments, piping can be broken down into four phases: seepage, retrograde erosion, clearing out and failure of the dike. The retrograde erosion phase is modelled by Sellmeijer. In this phase, channel formation is observed in the shape of sand traces (sandy spots without any crater formation), clean wells and sand transporting wells (sand craters). When sand transporting craters appear, the critical hydraulic head has almost been reached. The start of the next phase, clearing out (enlarging and cleaning of the channel from upstream to downstream), can be monitored only by using water pressure meters. The amount of transported sand increases significantly only when the channel reaches the downstream side. The process of clearing out may directly result in failure as soon as the channel reaches the downstream side, but it may also result in the deformation of the clay dike, partially closing the channel and therefore extending the duration of this phase. Failure takes place as a result of a significant increase in sand and water transport and the deformation of the dike. It has emerged that failure caused by piping is a real threat for dikes.

Further readingV.M. van Beek, H.T.J. de Bruijn, J.G. Knoeff, A. Bezuijen and U. Förster (2010) “Levee failure due to piping: A full-scale experiment”, Fifth international conference on Scour and erosion, San Francisco

FundingResearch programmes “Strength and Loading on Flood Defence Structures” (SBW) and “Flood Control 2015”. Staatsbosbeheer made the test site available

Contact:

Sand transporting well

Instrumentation detail at

piping location

Full-scale piping experiment

40 41

Development of DAM

The Dike Analysis Module (DAM) has been developed to make cross-sectional, short-term assessments of dike safety. DAM allows for rapid policy studies of flood risks. It can be used to back up operational decision support systems for flood emergency responses and for obligatory dike assessments.

The modular system uses four steps during the analysis, which are fully automated. The first step is gathering data, followed by the schematisation based on the collected data. Then the batch calculations are executed and finally the results are presented, for example in GIS.

For the automated system, the data has to be stored in general databases. The basic architecture for the databases was defined in 2009. The databases have to contain information about the geometry and construction of the dike, water pressures, subsoil and soil properties.

In addition, as part of the Flood Control 2015 research programme, a link has been established with the Flood Early Warning System (FEWS) for real-time dike safety analyses. A module has also been developed for automated modifications

han.knoeff@deltares.nl +31 (0)88 335 7244

erik.vastenburg@deltares.nl +31 (0)88 335 7291

in dike geometry in response to, for example, changes in water level. This module raises the dike until the necessary height is reached and, if necessary, a berm is added. This berm ‘grows’ until a safe profile is found.

Numerous calculations are needed to determine the safe profile. This consumes a lot of time with the traditional calculation models. To speed up the calculation process, a new type of algorithm has been developed. This genetic algorithm produces accurate results faster than traditional grid-based methods. The method has several advantages compared to grid-based methods. Firstly, the genetic algorithm can find the correct minimum, even when the solution space is very complex. The method is good at finding the global minimum (lowest factor of safety), even if there are several local minimums.

DAM has been integrated in Fugro’s REALTM (Rapid Engineering Assessment of Levees) concept, and tested on data available in the California Urban Levee Evaluation Program. AImost 1,000 different levee cross-sections were evaluated for three water levels and five failure mechanisms in less than 20 hours. This was approximately two orders of magnitude faster than conventional evaluation techniques in the USA.

Results of REALTM Californian pilot

Contact:

Typical Californian levee

Necessary dike height

Auto-adjustment of geometry

Automated berm

development

42 43

A ship on the beach...

As part of a consultancy operation relating to emergency conditions during the national Waterproef drill, Deltares was asked by the Delfland Hoogheemraadschap (HHD) to look at the suggestion that beaching ships could protect the Delfland coast. On the basis of an assessment of wave penetration behind a row of beached ships and the associated reduction in dune erosion, it was found that beaching ships considerably reduced the risk of a dune breach. Beaching ships to protect weak points in the coast was seen as an emergency measure of potential interest. An interdisciplinary follow-up study was therefore launched to look not only at the protection afforded by the beached ships but also at planning and legal issues. A team was established with representatives from HHD, Deltares, SMIT Salvage and the Ministry of Transport, Public Works and Water Management - Rijkswaterstaat.

The study conducted by SMIT Salvation showed that the total time needed for the controlled beaching of the ships is approximately 7 days, including mobilisation, unloading and preparing the ships. The “point of no return”, the point in time when the first ships are actually deployed, is after approximately 3–4 days. The Ministry found that ships can be requisitioned (for use or as property) only on the basis of unwritten emergency law.

On the basis of detailed hydrodynamic simulations, the protection afforded by a range of beaching configurations was examined. It emerged that, if the ships are positioned without excessively large gaps between them, there is a clear reduction in the erosion of the dunes behind them. The figures show the additional erosion or protection in red and green respectively for two of the seven beaching configurations studied. However, there is a local increase in the transitional areas between the protected and unprotected dunes. Erosion can also increase if one of the ships in the row is not positioned or is washed away.

dirkjan.walstra@deltares.nl +31 (0)88 335 8287

The controlled beaching of ships as an emergency measure for the protection of a weak section of coast would appear, in principle, to be a valid solution if a sound organisation can achieve the timely and accurate positioning of the ships on a sound legal basis. It should be pointed out in this respect that the risk of a local increase in dune erosion as a result of, for example, the washing away or collapse of a ship is considerable. The emergency measure can only be used if all other possible options have been exhausted and if the section of the coast in question will be breached given the expected storm conditions.

Contact:

Photo: Flickr CC by A. Connah

Additional erosion (red) and

protection (green) for two beaching

configurations

44 45

backgroundThe physical geo-ecosystem involves chemical and biochemical processes, as well as physical soil processes. Agriculture, industrial activities and urban development place a major burden on the subsurface. Changes in soil quality and in the associated groundwater and surface water systems and ecosystems are determined to a major extent by the transport of water and the substances present in that water. In addition to system knowledge, management considerations and the development of measures based on this knowledge, in-situ intervention in chemical and microbiological processes is opening up new ways of tackling soil contamination and soil improvement. Furthermore, there are many useful ways of exploiting the subsurface, such as heat/cold storage, the use of groundwater and minerals.

scopeAgricultural and industrial activities, and urban development, place a major burden

on the soil and groundwater system. At the same time, chemical and biochemical

processes in the subsoil have a major impact on risks for people and ecology.

Changes in chemical and biochemical quality in the soil, in the groundwater and in

the associated surface water systems and ecosystems are determined to a major

extent by the transport of water. Water and soil quality issues in relation to strategic

and operational management (dealing with agriculture, cultivation, drinking water

supplies) are also taken into account. Of course, water quality cannot be viewed

independently from the water quantity issues in the next section.

Sustainable land use in rural areas involves the sustainable use of natural resources and the prevention of the unacceptable degradation of soil quality and land use options: whether physical (load-bearing capacity or soil structure, for example), chemical (fertility of the soil, soil pollution) or biological (life in the soil). From the environmental perspective, the concept of “Soil Services” has been embraced. As well as ecosystem services, the soil supplies groundwater (protection of strategic drinking water resources), energy, and space for storage and transport.

This theme covers the links and interaction between the biotic and abiotic components of water and soil systems. Saltwater and freshwater systems are looked at in conjunction. Integration and innovation in chemical, biological and physical knowledge for the description, assessment and prediction of the sustainable functioning of the systems are central. The effect (cause-effect relationships) of natural and human stressors (climate change, for example) is studied so that answers can be given to questions from policymakers, managers and users of the soil and water system.

These issues result in five road maps: Eutrophication, Micro-pollution, Innovative design of soil and water systems, Modelling framework and monitoring, and Ecosystem health and ecosystem services.

46 47

Healthy water and soil systems

EXPOBASIN fit for purpose

Following the 2000 European Water Framework Directive and recent insights into sediment management on a river basin scale, Deltares developed an exposure model for the risk assessment of chemicals, both hydrophilic and hydrophobic, on a basin-wide scale. Exposure is defined as the concentration of hazardous chemicals in the aquatic environment. The model, called EXPOBASIN, establishes spatial relations between causes (pollution sources) and downstream impacts (ecological risk), taking into account the geometry, hydrology and fine-sediment dynamics of European river basins. Bio-availability and bio-accumulation are included in the assessment. As a result, the exposure can be quantified not only in terms of water concentrations, but also in terms of sediment concentrations and concentrations in biota. By using existing pan-European databases, applications to all European river basins can easily be set up.

The primary issue addressed by EXPOBASIN is the quantitative and objective ranking of chemicals and/or pollution sources with respect to their downstream impact on the ecology. It can, for example, be used to support risk assessment for the potential release of historically polluted sediments as a result of extreme floods, which is a major concern in different European river basins.

jos.vangils@deltares.nl +31 (0)88 335 8472

The EXPOBASIN model was set up on the basis of pan-European databases providing information about river-basin geometry, the input of fine particles due to erosion and land use. Furthermore, the model needs limited input data from the user about the river-basin hydrology and the environmental conditions. The river hydraulics are parameterised and form the basis for the calculation of the fate of fine particles. The fate and transport of chemicals are modelled on the basis of the previous steps, and on a database of chemical properties. This leads to calculated concentrations in water, suspended particulate matter and sediment. A bio-availability and -accumulation module provides estimates of the concentrations in the aquatic food chain (phytoplankton, invertebrates, fish, and top predators). As a final step, relevant indicators are calculated, expressing the relative environmental risk of the pollution source(s) under investigation.

The calibration and validation of EXPOBASIN with applications and assessments for five European river basins showed that the results for dissolved compounds were very good. In the case of compounds sorbed to fine particles, the validation of absolute exposure was only partly successful. However, it was demonstrated that the model can be used to rank chemicals or pollution sources. It was therefore concluded that EXPOBASIN is “fit-for-purpose”.

Further readingJos van Gils, Bert van Hattum, Bernhard Westrich, Exposure Modelling on a River Basin Scale in Support of Risk Assessment for Chemicals in European River Basins. Integrated Environmental Assessment and Management 5 (2009) nr 1 p 80-85

FundingProject Modelkey, 6th FP of the European Union

Validation of the EXPOBASIN model

Contact:

Sample results from EXPOBASIN:

the colours indicate the maximum

relative risk to the phytoplankton

community (expressed as Toxic

Units) caused by two pollution

sources, showing a clearly different

downstream impact of both sources

Set-up of the EXPOBASIN model

48 49

Emission module –

from emission data to

water quality

The Emission module is a new Deltares software product that helps water boards and other institutes to conduct pollutant transport studies. It was developed to calculate the effect of emissions as a function of human activities and hydrological characteristics in catchment areas. The emission module makes it possible to evaluate the effect that measures (such as the construction of wastewater treatment plants or a reduction in the use of fertilisers) have on pollutant emissions to the surface water system. It also allows scenario studies to be performed for issues such as population growth or hydrological conditions. The emission module can be seen as a “link” between emission data and water quality models.

The emission module consists of two components. The first is a Graphical User Interface for creating a network or reading a SOBEK rainfall-runoff network, and for defining emissions. The second is a calculation scheme for computing pollutant loads that can be used as input for water quality models. The emission module can run in stand-alone mode or in combination with the existing simulation model SOBEK. The data for pollutant sources can be taken from the national database, the “Emissions Register”, from

erik.degoede@deltares.nl +31 (0)88 335 8475

water boards’ own measurement data or from calculation rules based on emission factors which can be adapted by the user. The emission module enables the relatively straightforward set-up of a schematisation for catchment areas and it also runs in a GIS environment. The results can be used for reporting or as input in water quality models for surface water systems. So far, only the link with SOBEK-WAQ is operational. Links with other water quality systems are expected in the future.

The emission module can handle a flexible number of harmful substances. To facilitate the use of the emission module, all the substances from the Water Framework Directive programme and numerous substances from SOBEK-WAQ are used as a starting point for the emission module. The emission module contains a huge variety of functionality for many types of emissions (domestic wastewater, industry, paved drainage, unpaved drainage, rural drainage, greenhouses) and processes (decay, purification, influent of emissions).

The emission module was recently used successfully in several real-life applications. Several options are available at the output stage, such as time histories of daily emissions for a catchment area or pie charts for emission origins. Finance

• STOWA• Delft Cluster

Contact:

Emission origins for “Hagoort Hoog”

50 51

Time histories of emissions for

copper (Cu) and total nitrogen (TOTN)

Early Warning

Against Scums

Cyanobacterial surface scums (blue-green algae) represent a major problem in many recreational lakes in the Netherlands. Particularly during the summer period, cyanobacterial growth rates are high and cells may become highly buoyant, leading to the formation of large scums on the water surface during periods of stable weather conditions. As a result of transport by light winds, cyanobacterial scums often accumulate along lake shorelines, where the potential impact on recreational users is greatest. The ability to automatically forecast the timing and location of a surface scum several days in advance would allow water managers to make better decisions aimed at mitigating scum transport into recreational zones, and to inform recreational users better about potential health risks in the days to come. This is essential to ensure compliance with future requirements in the European Commission’s Bathing Water Directive, where minimising the exposure of recreational users to cyanobacteria and the possible implementation of a warning system are of primary importance.

The ultimate aim of this research is to develop a fully operational, stand-alone, early warning system for forecasting cyanobacterial surface scums in both small and large lake systems. The complete system, once incorporated into an operational warning system, will become an important management tool for various users.

The same four study lakes (Delftse Hout, Gooimeer-Eemmeer, Sloterplas and Westeinderplassen) examined in 2008 were again selected in the current study to conduct model simulation trials with the complete cyanobacterial bloom forecasting instrument. All four lakes are important for recreational activities, and they have frequent cyanobacterial surface blooms in the summer months. The objectives of the current study were to build on the progress made with model development and implementation in 2007, with a particular focus on further model testing in an operational (forecasting) environment. Overall, the model

simon.groot@deltares.nl +31 (0)88 335 8483

david.burger@deltares.nl +31 (0)88 335 5974

results were weak compared to the available field validation data for all lakes except the Gooimeer and Eemmeer, where scores were high but where the field validation data were very limited. The re-simulation of all model periods using observed rather than forecasted meteorological data did not lead to a major improvement in the mismatch between field and model output observed.

A number of further developments in the model framework through the refinement of the processes for scum appearance and disappearance were tested. The current model combines fuzzy logic with deterministic modelling and weekly resets of the phytoplankton biomass. The model application in its present form can be used to forecast the timing of surface scums, at least for smaller lake systems such as the Delftse Hout. Further testing to assess model performance with respect to the prediction of scum location and scum disappearance will be limited due to the absence of more detailed field validation data. These data need to be more quantitative and the frequency of the data needs to be higher. Further developments are also required to improve our understanding of the process of scum development.

Contact:

Blue-green algae at Almere-

Haven (Lake Gooimeer)

Model schematisation

Almere-Haven

Blue-green algae at Lake Westeinder

near Amsterdam

Hydrodynamic grid schematisation

for two models with different

resolutions

52 53

The origin of speciation

Although it is well known that environmental contamination with heavy metals has adverse effects on organisms, surprisingly little has been achieved in recent years in terms of actually linking chemical speciation to bioavailability (such as accumulation in organisms) in natural systems. This is the result of a lack of techniques for quantifying or actually measuring free ion activities (FIA) in pore water in sediments/aquatic sediments. The FIA concept assumes that metal ions in the Mn+ form, rather than total content or total dissolved levels, largely determine the biological effect observed in organisms exposed to water or sediment containing heavy metals. The methodological criteria for a suitable technique require it to be: 1) non-destructive for the sample; 2) capable of measuring small layer increments following redox gradients across water-sediment interfaces; 3) capable of time-dynamic measurements; 4) suitable for implementation in bioassay settings. A novel experimental “cell” was developed that meets these criteria. For the first time, it is possible to quantify free metal ion activities in undisturbed pore water both repeatedly and in a non-destructive way for the sample over a natural redox gradient. Bioassays are conducted simultaneously in the same setting. The design of the cell is based on using undisturbed samples in such a way that redox status and geochemical integrity is guaranteed. For the purpose of conducting bioassays, this setting is preferable to conventional methods which, by definition, produce unrealistic results for redox-sensitive compounds such as heavy metals.

For a variety of surface water types, chemical speciation was measured for the water-sediment interface. Simultaneously, aquatic organisms were exposed to these sediments to relate chemical availability to biological uptake. It was shown that the uptake of Cd, Cu, Ni, and Zn by the aquatic biota can be directly linked to free metal ion activity concentrations present in the overlying surface water. These

jos.vink@deltares.nl +31 (0)88 335 7154

findings make a significant contribution to our understanding of chemical speciation in water-sediment systems and the subsequent impact on organisms. We have demonstrated that the presence of benthic organisms in a water-sediment system has a significant effect on chemical speciation, and that it must therefore be considered during bioassays and chemical tests. Body concentrations are regulated by external concentrations that vary in time or, more specifically, by free ion activities. The conclusion is that an integrated cell of the type presented here provides the necessary experimental tool to support, in a mechanistic way, environmental risk assessments of contaminants and sounder quality criteria for aquatic sediments.

Further readingJ.P.M. Vink, The origin of speciation: trace metal kinetics and bioaccumulation by Oligochaetes and Chironomids in undisturbed water-sediment interfaces. Environmental Pollution 157 (2009) 519-527. This paper received the 2009 TNO publication award for Environmental Sciences

Contact:

Bioassay performed in the cell.

Uptake of heavy metals by aquatic

organisms (Limnodrilus) can now be

estimated accurately with the free

ion activity in overlying water as a

driver force

Chemical availability of dissolved

copper over time (above) measured

for water-sediment interfaces as

performed with the EU-patented

SOFIE® cell (below)

54 55

New methods for risk

assessment: organisms

are biotic ligands

Environmental quality standards for water bodies are generic values that apply to all surface waters. However, the chemical availability of heavy metals, and therefore their toxicity, depends greatly on the composition of surface waters. It is widely known that sites differ in terms of the observed toxicity of metals due to differences in pH, dissolved organic carbon and hardness. These parameters affect the bioavailability of metals and the extent of metal binding to organisms. The introduction of a site-specific evaluation may therefore improve the accuracy of risk assessment for surface waters. This concept of chemical availability was adopted in Biotic Ligand Models (BLM), which were developed for several heavy metals to account for differences in bioavailability in surface waters. BLMs for algae, crustacea, insects and fish are used to normalise “no-effect concentrations” (NOEC) observed in toxicity tests in accordance with the surface water of interest. Ranking NOECs for species in order of sensitivity allows for the construction of site-specific species sensitivity distributions (SSD). An SSD is a frequency distribution for the lowest NOEC for a species and all its toxicological end points (such as mortality,

jos.vink@deltares.nl+31 (0)88 335 7154

reproducibility, weight, etc.). The NOEC that offers protection for 95% of the species at that specific location is known as the HC5. The level of protection offered by generic quality standards (‘one concentration fits all’) is compared with the site-specific HC5 values.

Using validated BLMs for various metals, SSD curves have been computed for thousands of surface water samples in the Netherlands taken in the period 2006-2009. Geographical and temporal variation in site-specific NOEC and HC5 values is quantified on the basis of the measured concentrations. In this way, the sensitivity of individual species is visualised with the dots. All the dots for one location are collected in SSD curves. The SSD curves in the figure cover about 730 locations.

The figure shows a large range of sensitivity for locations and species. The HC5 values range over five log orders of NOEC. Surface waters on the left are considered to be very sensitive to the contaminant of interest (in this case zinc), while waters on the right are relatively robust. In the case of zinc, it was concluded that, in all cases where generic quality standards were exceeded, only 52% of those cases may be really at risk. An ecological analysis was performed by identifying the individual species or taxonomic groups in the SSD that may be at risk. This makes it possible to bring about major improvements in the effectiveness of measures that need to be taken to achieve “good chemical and ecological quality” (required by WFD), both in the environmental and economic sense.

Finance• RWS TO program LT water

management

Contact:

Concept of the biotic ligand model

(BLM), based on chemical speciation,

biological adsorption, and derivation

of a site-specific quality standard

56 57

Species sensitivity distributions

(SSD) for about 730 locations. Each

curve consists of a selection of the

most sensitive NOECs, which are

represented by the individual dots

Anaerobic benzene

degradation in the presence

of chlorate

Aromatic hydrocarbons are widespread in nature and often contribute to the pollution of soils, sediments and groundwater. The contamination of soil with mobile aromatic compounds, which are generally referred to as “BTEX” (benzene, toluene, ethylbenzene, xylene) has been seen at many industrial sites, especially those associated with the petrochemical industry. The in-situ bioremediation of sites contaminated with BTEX can take place both aerobically and anaerobically. The benefit of anaerobic in-situ bioremediation is that no oxygen supply is needed. Nevertheless, anaerobic in-situ bioremediation is less common for BTEX sites.

An alternative and promising strategy is the use of chlorate as an electron acceptor for the degradation of aromatic compounds such as benzene. Chlorate-reducing micro-organisms can reduce chlorate to chloride, with oxygen as a by-product. This biologically formed oxygen accelerates the degradation of compounds, which is a very slow process under anoxic conditions. The advantage compared to oxygen addition is the high solubility of chlorate in water – making it possible to add chlorate in high concentrations (> 100 g/l) to the groundwater – and the high in-situ production of oxygen.

For the first time, the principle of chlorate reduction was tested in the field. Push-pull experiments were performed to stimulate the degradation of benzene by adding chlorate. In the Netherlands, there is no regulatory limit for chlorate, and the addition of chlorate to the groundwater was allowed for this experiment. Chlorate-amended groundwater was introduced to an aquifer contaminated with benzene and falls in chlorate and benzene concentrations were monitored over time.

The addition of chlorate at the site resulted in a rapid fall in chlorate concentration, which coincided with a fall in benzene in the injection and monitoring wells. This level of benzene

alette.langenhoff@deltares.nl +31 (0)6 30 360 603

depletion was not demonstrated in previous push-pull experiments without chlorate. The result was the complete removal of 300 µg/l benzene within 4 weeks.

This shows that the anaerobic degradation of benzene and other contaminants in the presence of chlorate is a good alternative to known anaerobic and aerobic treatments. The degradation rate of benzene with chlorate as an electron acceptor was relatively high and similar to aerobic rates. A further advantage is the high solubility of chlorate, providing enough electron acceptor to treat high concentrations of benzene. Compared to aerobic treatments, chlorate addition can be valuable at sites where the addition of oxygen is difficult, for example because of large depths, large contaminant plumes, or low permeable aquifers. Furthermore, complete aeration of the site is not needed, and this mitigates the side-effects of changes in the geochemical composition of soil and groundwater.

Further readingA.A.M. Langenhoff, H. Richnow and J. Gerritse, Degradation of benzene at a site amended with nitrate or chlorate. Bioremediation Journal, 13(4) (2009) 180-187

Finance • Ministry of Economic Affairs• Oosterhof Holman

Sampling in the field

Contact:

58 59

Push-pull principle

Molecular detection tools

for microbiologically

influenced corrosion

The corrosion of steel subsurface infrastructure like gas pipelines results in high costs and constitutes a threat to the environment. Substances leaking from pipelines can have a major impact on groundwater systems. Two types of corrosion can occur: chemical corrosion and microbiologically influenced corrosion (MIC). Chemical corrosion can be controlled reasonably well. MIC, however, occurs very locally and quickly and so it is difficult to detect, predict and treat. To give an indication of the seriousness of the problem: 53% of pipeline excavation in the Netherlands was due to corrosion and, in 95% of cases, the corrosion damage was caused by MIC.

Many different types of micro-organisms can contribute to the MIC process. Various kits are available for the detection of MIC. These are mostly based on the culturing of micro-organisms from corrosion samples, in combination with visible detection based on, for example, the formation of sulphide. However, these methods largely underestimate the potential for MIC since it is usually the case that fewer than 1% of soil micro-organisms can be cultured at all. Moreover, these methods are laborious

bas.vanderzaan@deltares.nl+31 (0)88 335 7179

and time-consuming. Fortunately, tools for the detection of the enzymes responsible for MIC are more suitable. They provide information about the functional activity of a wide range of micro-organisms. For instance, different species of sulphate-reducing bacteria contain the same sulphate-reducing and hydrogenase enzymes as those often involved in corrosion in anoxic environments.

With molecular methods, it is possible to quantify micro-organisms and their activities quickly and, in many samples, simultaneously. The most suitable technique for this is quantitative real-time PCR. In the Deltares Geo Environment Research Laboratory, these quantitative PCR detection tools were successfully developed for several key enzymes involved in MIC. The methods were tested on corrosion samples, as well as on pure and mixed cultures of sulphate-reducing bacteria. Different MIC enzymes were detected in the various samples. In mixed microbial cultures enriched from Dutch river sediments, it was possible to quantify genes coding for four different MIC enzymes. These molecular detection assays can now be applied to environmental samples in future MIC studies.

The method provides quick and direct indicators which are specific for the MIC process. It can help in the early detection of MIC itself but also to understand the controlling mechanisms and the effectiveness of counter-measures.

FinanceEureka fund

Contact:

Detection methods for enzymatic

activity can serve as indicators for

microbiologically induced corrosion

in samples like this corroded steel

surface

Biochemical reactions of sulphate-

reducing micro-organisms that can

cause MIC

(A) Microcosm with steel coupons

inoculated with Desulfovibrio

indonesiensis (B) Steel coupons

60 61

Sustainable Use of

Ecosystem Services

It is claimed that Ecosystem Services (ES) constitute a practical concept for the sustainable use and management of our environmental resources. ES are the benefits (goods and services) that people obtain from ecosystems, i.e. from nature. They were formally defined in the United Nations 2004 Millennium Ecosystem Assessment, and grouped into four broad categories: provisioning, such as the production of minerals, water and food; regulating, such as the control of climate and disease; supporting, such as nutrient cycles, underground building and subsurface thermal storage; and cultural, such as spiritual and recreational benefits.

Ecosystem Services link human well-being to ecosystems and so address the complex interaction between socio-economic systems and ecological systems. They call for the joint multidisciplinary development of the understanding of that interaction by scientists, stakeholders and local residents. They have moved to the heart of EU environmental policy development. Some claim that they may also constitute a sound basis for the development of a common language and enrich environmental impact assessments. Ecosystem Services may also provide a new perspective for connecting environmental resource management to spatial planning, for example in case of the North Sea or the subsurface. However, promising claims have yet to be demonstrated in practice.

suzanne.vandermeulen@deltares.nl +31 (0)88 335 7730

jos.brils@deltares.nl +31 (0)88 335 7719

Moreover, there is a lack of practical guidance for the application of the concept.

Deltares therefore launched the Sustainable Use of Ecosystem Services (SUES) project to test the practicality of the ES concept in case studies and to establish practical guidelines for use. Literature reviews also generated a clear picture of the link between ES and biodiversity and of ES valuation concepts. Finally, a think-tank was established to inspire the project and to assess the outcome.

SUES combines knowledge about the application of sustainability concepts and ecosystem functioning. One of the case studies resulted in planning rules for the sustainable development of a new urban area and demonstrated how geo-information can be used for well-informed decision-making. The planning rules are based on the balance between opportunities offered by the (more or less) natural system, the ecosystem services such as bearing capacity of the soil and soil fertility, and the demands for the area, such as the number of houses or nature. Matching the design to the possibilities of the natural system as much as possible prevents problems (and costs) such as flooding and damage to buildings. The basic idea is to use the ecosystem services in a sustainable way and to avoid harming the quantity and quality of goods and services in the future or at other spatial scales. The planning rules can be helpful as boundary conditions for sustainable spatial design.

Further readingwww.riskbase.info(> downloads > project documents > discussion paper)

CooperationUtrecht Centre for Earth and Sustainability (UCAD)

Contact:

62 63

Planning rules

backgroundWater management means ensuring that there is enough clean water of the right quality for agriculture, the public and industry, sharing the water when there are shortages, and preventing damage and nuisance when there is too much water. Throughout the world, changes in land use and the climate are resulting in both water shortages and excess water. In the Netherlands changes in legislation and regulations in the area of spatial planning, in combination with these trends, require drastic measures. In the past, Dutch water management has focused primarily on the rural area from the perspectives of agriculture (drainage) and nature areas (raising water levels). However, the future of the densely-populated and water-rich Netherlands requires practical knowledge to help with water management in urban areas too. Water managers have discovered the city, and municipal authorities and project developers have in turn discovered the value of water.

As the subsoil forms the bottom layer of our ecosystem, with correspondingly long characteristic time scales, subsoil management has a specific responsibility with respect to the sustainability of measures. The use of soil as a building material

scopeWater management means having enough supplies of clean water, being protected

against excess water, and also coping with drought conditions. Subsoil management

includes heat and cold storage in the soil, as well as mining sand and clay as a resource.

Politicians and managers can be provided with optimal support by combining technical

expertise and risk information with insights from the exact and social sciences.

leads to irreversible changes on the surface. The use of the subsoil to store heat and cold raises questions about interference and spatial planning in the subsoil.

New regulations and changing ideas are leading to an increasing need for a coherent picture based on different perspectives. Technical and scientific knowledge is not enough here. Good communications with water managers are at least as important. Matter experts must be able to provide support for decision-making processes in the short term (operational management) and the long term (policy preparations). Thinking in terms of water levels and subsoil use should shift to thinking in terms of costs and benefits.

The road maps in this core domain cover water and soil: Basins and national water system, Regional water management, and Urban water management, Energy and water and Sustainable mining as a subsoil service.

64 65

Availability of water and soil systems

The implications of climate

change for the IJsselmeer

In late 2007, the Dutch government appointed an independent committee to advise on the long-term course of action needed by the Netherlands to deal with climate-related changes like rising sea levels, higher peak river flows and lower dry-season river flows. At the end of 2008, the report of this ‘Second Delta Committee’ revealed that climate change may plausibly cause a maximum rise in sea levels of 1.3 m by 2100. The IJsselmeer area is one of five regions where major measures were proposed to safeguard against flooding and maintain water supplies in dry periods. It is anticipated that, in the long term, a volume of water of 1.7 km3 (corresponding to a rise of 1.5 m in the IJsselmeer) is required to safeguard water supplies for agriculture and water level management in dry summers. The combination of rising sea levels and increased demand for water requires a decision about long-term water management for the IJsselmeer.

In the autumn of 2009, a group of policymakers from the IJsselmeer area requested a preparatory study of the options for, and consequences of, a change in water management, in anticipation of the formal policy preparations. Deltares was involved in the design of the process and supplied the various working groups with expert knowledge.

The study was designed as a joint fact-finding exercise, with three workshops involving some 70 experts from national and regional authorities as the central activity. The workshops were facilitated by teams of experts for the four main issues of water management in the region: safety; water management; ecology; and the potential for spatial planning and development.

During the first workshop the participants discussed the possible impact of a rise in the water level on these four issues. The workshop identified the main effects feared by various stakeholders in the region. It also showed that, as well as allowing a rise in the water level, demands for water storage can

gerda.lenselink@deltares.nl+31 (0)88 335 7817

be met by allowing an extra fall in the water level by the end of a dry period.

The second workshop addressed the effects of four distinctive policies for water management and proposed mitigation measures. The workshop concluded with the identification of four possible strategies for future water management. In addition to determining strategies, the workshop established substantial trust between the participants and commitment to their involvement in the eventual policy preparations.

The third workshop, to be organised in early 2010, will focus on the use of the results of the preparatory study in the follow-up process.

Contact:

66 67

Future flood risk in the

Rhine basin

Climate change will increase winter precipitation and, in combination with earlier snowmelt, cause a shift in peak discharge in the Rhine basin from spring to winter. This will probably lead to an increase in the frequency and magnitude of extreme floods. It is expected that the probability of flooding in the Rhine basin in 2050 will be two to five times as high as it is today, assuming that no additional flood management measures are implemented. Population growth and rising property values in flood-prone areas further enhance future flood risk. Flood risk projections involve numerous uncertainties. For example, extreme value analyses of flood probabilities in 2050 are difficult to make and different methods are currently being debated. Furthermore, there are no projections available for the basin-wide potential damage.

aline.telinde@deltares.nl+31 (0)88 335 7761

The central aim of this research is to focus on the probability of extreme flood events and to simulate the effect of climate change on future flood peaks in the Rhine basin. This information can be used to develop and evaluate cross-boundary flood management strategies. Recent scientific literature has described the need to move away from traditional flood frequency analysis, since climate change undermines the basic assumption of stationarity. We therefore adopted a process-based approach including different climate change projections, a rainfall generator, and hydrological (daily) and hydrodynamic (hourly) modelling, the aim being to estimate changes in low-probability flood peaks and the impact of measures.

The embankments along the Lower Rhine in Germany and in the Netherlands have very high safety norms of 1/500 and 1/1250 years, respectively. Our results showed that, in the most extreme climate change scenario, associated design discharges increase by 17%. Due to the difference in safety levels, however, upstream flooding in Germany may occur, reducing peak discharges downstream in the Netherlands by up to 15%. The only effective measure at the basin-wide scale that can reduce flood probability is drastic dike heightening, while measures such as extra retention basins, reforestation and bypasses can be beneficial at the local scale. However, in a risk-based approach, more could be gained by damage reduction than flood defence measures in terms of reducing flood risk. Calculations to estimate potential damage in the Rhine basin are in progress.

Further readingA.H. te Linde, J.C.J.H. Aerts et al, Simulating low probability peak discharges for the Rhine basin using resampled climate modeling data. Water Resources Research, 46 (2010) W03512

FinanceBSIK KvR Climate changes Spatial Planning. A7 ACER. Adaptive capacity to extreme events in the Rhine basin

Contact:

The Rhine at Cologne

Extreme value plots of yearly

maximum discharges of the Rhine

at the German-Dutch border. 1000

years of daily meteorological

input data obtained by a weather

generator served as input for the

rainfall-runoff model

68 69

Groundwater age

It is known that point sources of pollution, such as leaky oil tanks, septic tanks and landfills are a threat to groundwater quality. The threat from diffuse sources of pollution is less familiar. Diffuse agricultural pollution – the leaching of high concentrations of nitrate, artificial pesticides and heavy metals – poses the main threat to groundwater quality at the regional scale.

The long travelling times of pollutants through groundwater bodies mean that the early detection of deterioration is necessary for the efficient protection of groundwater quality. The early detection of deterioration is often complicated by limited monitoring data, variations in the transport of contaminants towards monitoring locations, variations in the application of contaminants in space and time, and degradation/partial degradation of contaminants in the subsurface.

ate.visser@deltares.nl +31 (0)88 335 7167

Deltares wants to develop and improve tools to detect trends in groundwater quality that take into account the reactive transport of pollutants from the ground surface to the monitoring screen. One component of this research focuses on including the travelling time of pollutants in the methods for trend detection given the fact that several analytical techniques to determine the travel time or age of groundwater samples have become widely available in recent decades.

Once groundwater ages are available, time series for groundwater quality can be re-analysed to study the trends in groundwater quality. Each of the groundwater quality measurements is linked to the year of infiltration using the groundwater age. The result is a groundwater quality–recharge year relation, which can often be linked directly to the historical intensity of the use of fertilisers and manure on agricultural land.

This approach was tested with groundwater quality data from the province of North Brabant in the Netherlands. North Brabant is one of the areas in Europe which is most affected by agricultural pollution.

The results showed that groundwater quality has actually improved since 1990 in North Brabant. Concentrations of nitrate and other contaminants related to agriculture have fallen in groundwater that has recharged since 1990. This improvement in groundwater quality may be attributed to legislation implemented in the past twenty years, which actually aimed to reduce the leaching of nitrate and phosphate to surface water and groundwater.

Contact:

Conceptal groundwater model

Zand-Maas, pilot study

commissioned by RIVM

70 71

PEAT-CO2: modelling water

depth in Southeast Asian

peatlands

Peat soil consists of 90% water and 10% vegetation remains. Peatlands are therefore not really ‘land’ but wetlands. In some ways, they need to be managed rather like water bodies to prevent the loss of the water that supports the peat surface. In this way, it is possible to prevent drying out of the peat and the associated consequences: subsidence and the consequent flooding, fires, and habitat loss. Until now, most land use planning and water management for peatlands in SE Asia have failed to recognise this fact, even though the area involved amounts to 27 million hectares, i.e. 10% of the region’s land area, covered by tropical rainforest in its natural state. This shortcoming results in the largest land-use-related carbon emission source in the world (equivalent to 3-8% of global fossil fuel emissions) and the largest concentrated fire area in the world (amounting to over 5 million hectares in dry El Niño years). Moreover, it implies an enormous potential loss of usable land in the region: peatlands make up 65% of Indonesia’s lowland area. Another possible consequence is one of the fastest and most concentrated losses of biodiversity in the world.

The PEAT-CO2 (Peatland Emission Assessment Tool) project was launched in 2006 with the aim of enhancing the scientific basis for improved land use planning and water management in peatlands, focusing on SE Asia. The R&D results have allowed the development of a series of advisory projects in the region for governments and the private sector. Most of these activities aim to support project development under the new REDD (Reduced Emissions from Deforestation and Degradation) climate mitigation mechanism.

The two main ongoing research activities are the development of a platform for spatial planning and the assessment of carbon emissions and land subsidence, and the development of a platform for drought and fire monitoring and prediction. The main goal of the second activity is to investigate the feasibility of

aljosja.hooijer@deltares.nl +31 (0)88 335 8170

ronald.vernimmen@deltares.nl+31 (0)88 335 8373

developing an operational and accurate fire risk monitoring and prediction system for SE Asian peatlands. A fire risk prediction system of this kind involves a sequence of models: as a first step the peatland groundwater depth in SE Asia was modelled in near-real time using satellite-derived rainfall estimates such as TRMM and CMORPH. Furthermore, an indicator of fire risk was traced back to the groundwater depth. A significant component of spatial and temporal patterns in fire occurrence (as observed by the MODIS satellites) could be explained by water depth. Much of the remaining unexplained variation in fire occurrence could be explained by land use patterns.

When interpreting these results, it should be noted that the groundwater depth model applies to undrained conditions; it therefore underestimates water depth in drained areas. It should also be clear that it is not low groundwater depth itself that causes fires. However, it does create conditions where fires lit by people, mostly to clear land, can spread rapidly.

Contact:

Modelled average annual lowest

water depth in peatlands, 2002-2008Modelled peatland water depth

(monthly median of daily minimum)

per Province/State

72 73

MODIS monthly unique fire hotspot

counts per Province/State as a

percentage of peatland area

(1 hotspot cell = 1km2)

Observed and modelled monthly fire

‘MODIS hotspot’ counts in Central

Kalimantan as a percentage of the

‘open and degraded’ peatland area

The feasibility

of Blue Energy

Increasing demand for electric power, in combination with CO2 emissions from, and the scarcity of, fossil fuels, means that new energy sources are needed. One possible renewable energy source is salinity gradient power, which uses the difference in salinity between river and sea water to produce electric power (Blue Energy). In the Netherlands, there are several possible locations where this idea can be used. At present, renovations of the sluice complexes in the Noordzeekanaal and the Afsluitdijk, where Blue Energy might be feasible, are under consideration.

Two techniques are under intensive investigation in laboratory-size facilities: Reverse Electro Dialysis (RED) and Pressure-Retarded Osmosis (PRO). Assessing the feasibility of the techniques on the basis of these laboratory results generally results in an over-estimation of the potential of the technique. Deltares therefore studied the technical and economical feasibility of a complete osmotic power plant based on commercially available membrane parameters. For the purposes of the feasibility study, we developed a numerical model of a PRO power plant, including a hydrodynamic and mass transfer model at the membrane level, an aggregation model at the plant level and a basic lifecycle cost model.

The membrane model takes the concentration polarisation in the membrane layer into account, as well as the decrease in salinity due to the water flow through the membrane. The plant level model computes the gross and net power production for different combinations of salt-fresh water discharge ratio and salinities, trans-membrane pressure and membrane parameters. In the final step, a basic lifecycle cost analysis enables the computation of the optimal set of parameters for a specific location.

Due to flow effects, size effects and the realistic salt-freshwater ratio, the gross power output for real size membranes (in the order of 1 m2) is about 1/3 of that for laboratory size membranes

ivo.pothof@deltares.nl+31 (0)88 335 8448

(area of 65 cm2). This can be improved to 2/3 by using a countercurrent flow instead of a cocurrent flow.

It is technically feasible to use commercially available, flat sheet membranes to produce energy with the PRO process. The price would be € 1.14 per kWh, mainly due to the anticipated extensive saltwater treatment. If this pre-treatment of seawater can be minimised by modifications to the module design or by using hollow-fibre membranes the cost price falls to € 0.44 per kWh, which is comparable to solar power.It is economically feasible to produce power with the PRO process with flat sheet membranes using a highly concentrated brine flow (200 g/l, about 6 times that of sea water). The price would be € 0.11 per kWh, which is cheaper than wind energy and below the current market price.

The feasibility of a PRO power plant at the sluice complex of the Noordzeekanaal was specifically investigated. The contour plots of the net power output and the cost price for a range of available salinities in the area apply to this case.

CooperationThe model was developed in cooperation with leading global companies in the RO industry: NORIT PT, Dow Chemical R&D and Lenntech BV

Contact:

Cost price (€ / kWh) for a range

of fresh and salt water salinities,

including extensive saltwater

treatment

Net power output (in MW at

40 m3/s freshwater flow) for a

range of fresh- and saltwater

salinities

74 75

The “Waterverdeler”: serious

gaming as a tool for providing a broad

public with complex knowledge

Play the “Water Distributor” game!The Netherlands and water have a love-hate relationship. We do not want too much, but nor do we want too little. The aim is enough good-quality water. This is a challenge involving difficult choices, with creativity often playing an important role. A job that you can only do when you are aware of the importance of water for us and our environment.

The Water Distributor lets you learn for yourself. Send the river water that flows into the Netherlands to the areas where it is needed. Watch out for salt getting in. Prevent drought damage in the summer. Keep the IJsselmeer at the right level. Manage it all with the locks and weirs in the main water system. Play the game at www.waterverdeler.nl (in Dutch).

The Water Distributor takes players step by step deeper into the complexity of Dutch water management. Players are drawn into the game, allowing them to gain an understanding of the complex world of water management quickly and easily. The Water Distributor is free to visit at www.waterverdeler.nl. The developers hope as many people as possible will use the game.

ronald.roosjen@deltares.nl+31 (0)88 335 7840

micheline.hounjet@deltares.nl+31 (0)88 335 7391

All they ask is that you think about the best way of working on education. Knowledge in exchange for knowledge really is the aim.

The Water Distributor was developed by Rijkswaterstaat, Deltares and Tygron Serious Gaming under the auspices of the Water Innovation Programme (WINN) with support from Living with Water.

The Dutch Minister of Transport,

Public Works and Water Management

has just finished playing the game!

Workshop with the Water Distributor

Contact:

76 77

backgroundPressure on the available space is increasing. Maintaining the quality of life and the habitat is becoming an ever more urgent problem both in the Netherlands and in comparable deltas throughout the world. As the limits of what is possible or desirable onshore and above ground have been reached, the sea and the subsurface are increasingly coming into the picture.

Worldwide developments like climate change, the increase in sea shipping transport and spatial demands in coastal areas are the driving force behind the expansion of harbours, construction of breakwaters, land reclamation, and artificial islands. Rising demand for energy requires oil platforms further offshore and wind turbines in the nearshore area. Onshore, the “third dimension” is increasingly coming into the picture during the urban planning process. However, public willingness to tolerate nuisance during both the construction and operational phases of the required transport infrastructure is steadily declining. People are no longer willing to accept damage to their physical living

scopeSustainable living in delta areas requires an understanding of building on and in

soft soils. Underground construction, as well as onshore and nearshore transport

infrastructure, contribute to a habitable and prosperous country. The challenges

involved in foundation and hydraulic engineering are becoming more demanding

for several reasons: increasing population density, mobility, and prosperity; the

increasing shortage of space; the softer nature of the land that is still available; and

public demand.

environment, or nuisance caused by noise, vibration, dust or inaccessibility, either for underground works or for roadworks. In addition, the construction sector has acquired a negative image in terms of cost control and planning delays. These problems are closely related to a lack of risk management, with the soil and subsurface being a major factor. Intelligent use of existing knowledge is a key factor in this respect.

Some of the projects in this theme map are being implemented as Joint Industry Projects (JIP). The private participants determine the scope in a project of this kind, and the Ministry of Economic Affairs supports these projects through research grants for Deltares. The knowledge products initially benefit the participants but, in a broader sense, they support the knowledge position of the Dutch corporate sector abroad. Hydraulic engineering is a major Dutch export product, a fact that is also emphasised by the Netherlands Water Partnership.

Seven road maps have been defined in this theme. Access to and transport on water, Offshore developments and Hydraulic engineering focus on the ‘water’ aspects in this theme. Sustainable infrastructure and Underground construction concentrate on different types of linear infrastructure. Adaptation of soil properties focuses on the use of micro-organisms to improve soil (SmartSoils), and Information systems (DeltaBrain) looks for new ways of re-using existing knowledge.

78 79

Living and building in the delta – lack of space

Material Point Method for

large deformations

In geomechanics various processes like the installation of piles and hazards such as landslides involve large deformations of soil. Obtaining reliable predictions of such complex deformation processes proved cumbersome due to the computational effort imposed by available numerical methods and the limits of applicability of these methods. Further complexity is added to large deformation problems by the highly non-linear mechanical properties of granular materials.The drawback of the widely used Finite Element Method (FEM) lies in its reliance on a mesh. Strong mesh distortions during large deformation analyses render the FEM prone to numerical problems that are difficult to overcome. The disadvantage of fully mesh-less methods such as the Smoothed Particle Hydrodynamics appears to be the involved high computational cost.In the framework of an EU funded research project named Geo-Install, a mesh-free method called the Material Point Method (MPM) is being developed at Deltares with support of universities in Stuttgart, Stellenbosch, Glasgow and Delft for the analysis of both dynamic and quasi-static problems. At present, the emphasis lies on modelling cone penetration and pile driving.Static cone penetration testing (CPT) was invented in the Netherlands for the purpose of finding sand layers for pile foundations, but meanwhile it has become an in-situ test for soil profiling as well as estimating soil properties on strength and stiffness. Many fully empirical correlations have been proposed for the extrapolation of CPT measurements to soil properties, but as yet many of them require independent verification as might be done by numerical simulations. Obviously, this requires a large-strain analysis as possible with the MPM.Shear stresses for a deep CPT penetration into clay have been computed in a large area around the CPT tip. At the shaft just above the tip of the cone, the computed stresses can directly be compared to measurements at the so called friction sleeve. Similarly, this can be done for the resistance at the tip of the cone.

lars.beuth@deltares.nl +31 (0)88 335 7523

john.vanesch@deltares.nl +31 (0)88 335 7457

pieter.vermeer@deltares.nl +31 (0)88 335 7307

At this very moment the MPM works nicely for clay penetration. The challenge is now to perform these computations also for sand.Also dynamic processes can be modelled, like a projectile being shot into soil. The problems encountered in this analysis are very similar to the ones that occur in pile driving, the second focal point of the ongoing research. As for quasi-static penetration, soil-metal contact has to be modelled, but on top of this, inertia forces create stress waves so that a fully dynamic approach is required. Meanwhile, first simulations have been done for pile-driving in dry soil, but the challenge is now to extend these to saturated soil and to predict pore water pressure waves. Indeed, commercially available software exists for large deformation problems, but not in the case of dynamically loaded saturated porous media.

FundingGeoInstall (EU)

Contact:

Quasi-static MPM simulation of

shear stress from a CPT in clay

Dynamic MPM simulation of shear

strains from a sphere shot into clay

80 81

Unstructured grid

modelling

Hydrodynamic modelling for freshwater topics is generally based upon Sobek-1D2D. This program is particularly suitable for modelling river flow, channel flow, sewer flow and 2D flooding and it covers both sub- and supercritical flow regimes. Most work on estuarine and coastal issues, on the other hand, is performed using Delft3D, which is particularly suitable for model tidal propagation in seas and estuaries, storm surges, flows in rivers, harbours and lakes, salinity intrusion and thermal stratification.

In the new hydrodynamics package Unstruc, we aim to combine the efficient and well-proven methods of both packages into one hydrodynamics modelling system. It is based on a fully unstructured network, yielding optimal flexibility. The curvilinear grid approach is adhered to as much as possible because of its high accuracy, but one can easily switch to an unstructured approach locally to circumvent its occasionally less beneficial properties. To help users create these new types of networks, we have added curvilinear grid generation in channels or rivers and along coastlines, and triangular grid generation in intermediate areas. The various grid areas can be coupled automatically. Local refinement of grids is now possible, as is automated refinement based upon local bathymetry.

The physical and numerical model features of Unstruc are being extended gradually by importing functionality known from Delft3D and SOBEK. In 2009, we conducted several initial tests with 3D (z-layer) problems based on the k-ε-model. One-dimensional flow networks can now also be coupled to the 2D flow areas, such as model small rivers leading into a lake. Two of our 2D-test applications are a full-scale continental shelf model and the Sacramento delta in the San Francisco bay area.

herman.kernkamp@deltares.nl+31 (0)88 335 8521

arthur.vandam@deltares.nl+31 (0)88 335 7689

To facilitate the rolling out of Unstruc to users, file-based model input and model output were implemented. For this purpose, we adopted the international NetCDF standard. We are working on a standardisation of solution data for unstructured grids in cooperation with international parties.

In 2010, we will add further modelling capabilities for 1D structures, such as weirs and pumps. In 2D modelling, we will extend the possibilities for boundary and initial conditions and discharges. We also intend to link Unstruc to the water quality package Delwaq and to extend 3D modelling, for example with flexible layers in the vertical direction.

Contact:

Water height in continental shelf

model run

Detail of Unstruc mesh in

Sacramento delta

82 83

Courantnetwork: automatic

bathymetry-based refinement

River groynes

Groynes along river banks are mainly there for shipping. Maintaining a clear course with sufficient water depth so that ships can sail as long as possible during the year is a major concern. However, there are other benefits: the smooth transport of ice floes during severe winters and the protection of river banks. In Dutch rivers, a vast number of groynes were built in the nineteenth century and, since then, nature has had few opportunities to modify river courses. Nowadays, we are so accustomed to groynes that we think of them as part of the typical river landscape. Of course, they are not. There has even been the development of an exotic type of nature, flourishing in the rocky structures of the groynes, while the sandy river type of bank ecology has declined. The river authority (Rijkswaterstaat) is looking for ways to lower maintenance costs and, at the same time, restore the original ecology while preserving the main functions of groynes. In addition, the flow resistance of the groynes during high river flows is considered a disadvantage and different groynes may reduce resistance.

An invitation to private companies to submit ideas (in a contest in 2006) led to several new concepts which were elaborated further in 2009 as part of an innovation programme (WINN). Mathematical computations, scale model testing, location choices and in-situ testing (with prototypes) were conducted with two promising ideas: the Royal Haskoning concept ‘Island groyne’ (Eilandkrib), and the Arcadis/Alkyon & Robusta self-regulating groyne (Zelfregulerende krib).

The island groyne is expected to reduce irregularities in the river bed and it allows a modest flow in the groyne sections parallel to the river flow, encouraging sandy river ecology. The groyne structure is made from the same type of material as conventional groynes (often basalt). It is probable that fewer island groynes will be needed to produce the same effect for shipping as conventional groynes, and this will reduce maintenance costs.

maarten.vanderwal@deltares.nl +31 (0)88 335 8074

tom.jongeling@deltares.nl +31 (0)88 335 8191

rob.dejong@deltares.nl +31 (0)88 335 8267

This concept was further elaborated in a pre-design for specific locations and some 3D computations were made.

The self-regulating groyne is an alternative to a complete groyne structure. It consists of a woven fabric hanging from floating fenders of inflatable material that are fixed to the river bed. The idea is that, during high river discharges (and high water depths) the fenders will be pulled under water, crease as a result of water pressure and eventually sink to the river bed. A laboratory model demonstrated this. Further in-situ tests are planned for 2010.

A combination of the two ideas is also possible: a robust island groyne with a major section of the connection with the river bank consisting of a self-regulating groyne, allowing low flow resistance during high river discharges. Finance

WINN programme

Contact:

Scene of a Dutch river

(Photo: Rijkswaterstaat)

Island Groyne (Royal Haskoning)

Self-regulating groyne: a: at low

water level, b: at high water level

(Arcadis/Alkyon & Robusta)

a

b

Depth profile with erosion (blue)

visible near to the groyne

84 85

Large-scale wave impacts

Many coastal structures like caisson-type breakwaters and storm surge barriers have vertical faces that can be exposed to wave impacts. The load exerted by wave impacts on vertical structures can be very high and can ultimately lead to structural failure. However, despite many earlier investigations, the process is still not very well understood.

One important issue is the influence of scale effects, which is still not known. Large-scale data for wave impacts are therefore needed. So Deltares seized the opportunity to join forces with the offshore industry and participate in new large-scale measurements of pressure fields on a vertical wall under wave impacts. These measurements were conducted in collaboration with the Joint Industry Project SLOSHEL, which focused on sloshing impacts in LNG tanks.

To make it possible to study different types of breaking wave impacts, a focused wave signal was developed which produces a wave that propagates over a flat bed, and breaks at a designated location. The breaking point of the wave can be shifted to direct the type of wave impact. This is done by creating a wave train with waves that gradually increase in length and height. The larger waves are faster and overtake the smaller waves. In this way, all the energy is concentrated in a single high wave near the wall. The signal was made in such a way (using non-linear wave theory and some tuning) that this final wave becomes too steep and breaks against the wall.

Large-scale tests were undertaken in the 200 m long, 5 m wide, and 7 m deep Deltares Delta Flume. A wall was built consisting of a 1.5 m thick concrete wall and a steel support. The front wall contained a measurement section with high-resolution pressure sensors (smallest vertical spacing of 6 cm). The various parts of the front concrete wall could be rearranged to position the measurement section in the impact location. MARIN installed 10

bas.hofland@deltares.nl+31 (0)88 335 8196

pressure sensors with a high sampling rate in the impact region. Deltares provided another 13 pressure sensors over the height of the wall. A large number of impacts were created, with different water depths and different types of breaking waves.

The tests generated a unique and valuable data set of wave signals and accompanying impact pressure profiles. High pressures of about 100 times the wave height were measured. Moreover, the total forces measured were about 2 to 6 times larger than the values calculated with existing design formulae. This knowledge can be used to make design coastal structures in delta areas on safer lines.

Further readingB.Hofland, M.L.Kaminski, G.Wolters, Large-scale Wave Impacts. Intern. Conference on Coastal Engineering, ICCE2010, Shanghai

Finance• Sloshel consortium (GTT,

MARIN, Bureau Veritas, Lloyd’s Register, ABS, Shell, Chevron, DNV, ECM and ClassNK)

• Deltares

Contact:

86 87

Scour – a recurring problem

in the North Sea

On sandy sea beds, like those in the North Sea, currents and wave action can generate local seabed erosion. This effect is called scour. This happens, for example, around jack-up platforms used to drill wells in new oil and gas fields or foundations for offshore wind turbines. Excessive scour can reduce foundation fixity in the seabed and lead to undermining, jeopardising the stability of the structure. However, there are no guidelines available for scour assessment, scour prediction or scour protection design for jack-up platforms. In other words, how to deal with this problem is a pressing issue for users, owners and designers of jack-up platforms and one they would be glad to see answered.

Together with a number of offshore companies, Deltares launched the Joint Industry Project “Offshore Scour Assessment and Remedial Measures (JIP OSCAR)” in October 2008. The project comprises a desk study, physical modelling, software development and a field case workshop. The desk study summarises relevant scientific literature about offshore scour, derives a generic recipe for scour assessments and generates a series of engineering graphs to support quick scans of the scour potential.

The first set of physical modelling tests was carried out in 2009. The industry required not only maximum possible scour depths but also the rate of scour development, and this triggered innovations in measurement techniques and in the transformation of model data to reality. The innovative measurement system consists of a high-resolution digital camera with a fisheye lens mounted in a transparent foundation. During physical model testing, the camera records images with a frequency of up to 6 Hz. This provides an insight into the physical processes involved in the turbulence-induced displacement of scour protection, suction removal of sand between stones and micro-avalanching, the geotechnical slope failure and infill of the scour hole. Camera images are automatically processed to derive

daniel.rudolph@deltares.nl+31 (0)88 335 8362

tim.raaijmakers@deltares.nl+31 (0)88 335 8218

quantitative information on scour and backfilling development as a function of time and position around the foundation.

By 2010, a systematic database of scour measurements for various types of jack-up design will be available to the JIP participants, including guidelines for scour-friendly jack-up design, prediction tools for scour depths around and below jack-up foundations, and a scour management tool – OSCAR – that can assist in scour prediction and the conceptual design of remedial measures. This engineering software computes all relevant hydrodynamic parameters, scour depths and the performance of a user-defined scour protection layout. The input menu allows for the import of time series of waves, currents and water depths. In this way, scour computations can be made to hindcast scour events during operations, to predict scour for future operations or to prepare online scour predictions during an operation. The modular set-up of the program allows new structures and scour protection types to be added in the future. This means that OSCAR can be applied to any kind of offshore structure, such as monopile foundations, jackets or gravity-based foundations.

FundingJIP OSCAR

Contact:

88 89

Implementing risk

management

The implementation of risk management in the construction industry often runs up against obstacles to routine application. This research aims to provide guidance for the effective organisational implementation of risk management by explicitly considering the role of individual professionals, their organisations and the characteristics of risk management methodologies. The developed knowledge base is also useful for implementing technical and organisational innovations in organisations.

Post-graduate courses were developed to distribute the developed knowledge. A package of methodologies and instruments to support local authorities in managing risks in urban development and construction projects was based on lessons learned from numerous cases. Subjects that may be relevant are the roles of civil servants, heads of departments, consultants, contractors and clients because they have quite different views of risks and the organisational embedment of risk management.

The routine application of existing methodologies and instruments may enable organisations to move forward with the professionalisation of risk management. This approach provides an understanding of the nature of obstacles to routine application. It also indicates how the right conditions can be created, both for individual professionals and organisations.

A knowledge product of a different kind is knowledge mediation during the introduction of new policies. Stakeholders often deal with complex issues by initiating new policies. Even so, it remains difficult to envisage whether the intended policies will be effective. The result is often a process of struggle and conflict about what is just and desirable.Pro-active mediation between conflicting information and assessments from experts, authorities and stakeholders can be achieved by initiating a ‘knowledge mediation’ procedure as an

martin.vanstaveren@deltares.nl+31 (0)88 335 7283

dirk.pereboom@deltares.nl +31 (0)88 335 7433

marc.rijnveld@tno.nl +31 (0)15 269 5421

exploratory stage of the implementation of a new policy concept. This is a variation on conflict mediation and the aim is to reach agreement between parties about the relevant knowledge to be used in decision-making. This involves interventions in a knowledge dispute by “an acceptable third party who has limited or no authoritative decision-making”. Experts are not involved as stakeholders, yet they can provide decisive knowledge. A mediated knowledge dispute can be seen as a social learning process in which participants – assisted by experts – are invited to contribute to a shared knowledge base from their own perspectives and learn from the knowledge and values of others.

Further readingM.T. van Staveren, Risk, Innovation & Change: Design Propositions for Implementing Risk Management in Organizations, PhD thesis Univ. Twente, 2009

FinanceThis is a Delft Cluster product

Contact:

‘Koopgoot’, Rotterdam

Shopping Mall

Construction of underground car

park for a future apartment complex,

Delft, Netherlands

90 91

DeltaBrain

DeltaBrain is the virtual learning and working environment for present and future generations of delta engineers. This system combines knowledge and practice with existing sources of knowledge such as numerical models, measurement data and expert knowledge from a range of disciplines. The aim is to open up access to all the available relevant knowledge and, in this way, to accelerate and improve decision-making and risk management.

One of the tools developed in 2009 focused on establishing an insight into the risks associated with Horizontal Directional Drilling (HDD). During HDD, unforeseen problems often crop up in practice because the situation in the subsurface is different than is initially thought. Geological and geotechnical knowledge have been brought together in order to determine which conditions in the subsurface can create problems for HDD. Swelling clay can close off the borehole, preventing pipes from being pulled out. The presence of layers of gravel can destabilise the borehole. And large obstacles such as rocks or remnants of tree trunks can be a problem if the drilling head gets stuck in them.In the TNO Geotop-project, the top 30 m of the subsurface of the Netherlands has been broken down into a number of areas in which the subsurface is structured in characteristic ways. The geological formations in each area have been determined using the national Digital Geological Model (DGM), and the average depths and standard deviations have been calculated. The geological characteristics are linked to geotechnical properties and, for each geological formation and each area, risk estimates have been made on the basis of prevalence. This information is then made accessible and shown in a map of the Netherlands in which, for each area, the risks for HDD are stated. The SoilRisk module will be implemented in 2010 in GeoBrain boring technology, with expert knowledge being made widely accessible.

mandy.korff@deltares.nl +31 (0)88 335 7466

mike.woning@deltares.nl +31 (0)88 335 7357

The predictive model for sheet piling (GeoBrain Foundation Technique) was validated in 2009. Designers can use the GBF model to make more accurate predictions of the risk of damage during the execution of the foundation design than with the current formulas in the CUR guideline 166. Validation of the model proved, incidentally, to be more awkward than expected. In particular, the accuracy of negative predictions is difficult to check because the probability of actual execution is low in those cases. In addition, a study by the EIB (Economic Institute for the Construction Industry) has shown that GBF can lead to savings in direct costs. It is expected that the indirect gain from reducing delays, claims and damage to reputation is much higher. Nonetheless, the economic value has not been the deciding factor until now. The main obstacle to the use of GBF has been the segmentation of the construction industry. In the worst case, everybody passes the buck. Construction risks are often wrongly pushed along to the construction phase, even though they can in fact be managed effectively in the design phase.

Further reading• www.tno.nl, search Geotop• www.geobrain.nl/en look

at drilling technology and foundation technology

Finance• Deltares• TNO

Contact:

Cross section of tidal channel,

detailed 3D model of sandy channel

and clayey tidal flat deposits

Geotop-based HDD risk map

HDD in practice (Photo: VSHanab)

92 93

Lateral loading of piles

due to embankment

construction

A number of Delft Cluster projects started in 2003 with the objective of improving the predictability of soil deformations. One of these projects was the sub-project ‘Piles horizontally loaded by soil’. To optimise the link with practice, this sub-project was housed with the eponymous CUR committee H408 in late 2005. This committee brings together contractors, engineering offices, clients and research institutes to investigate the subject. Efforts have been made to obtain a widely supported design guideline that leads to a substantial quality improvement in predicting deformations and forces in structures.

On the basis of a literature study and discussions with the members of the committee, a survey was conducted of generally accepted Dutch design practice for piles horizontally loaded by soil. The research involved the selection of a number of the existing design methods/models and testing them using a number of available field measurements and a centrifuge test.

In addition to the predictability of the horizontal soil deformations, the CUR committee also looked at the pile-soil interaction and the influence of creep and crack formation in a prefab concrete pile on the pile behaviour. A number of methods for determining creep and crack formation in concrete were also investigated, as was their effect on the stiffness of a concrete pile.

On the basis of the analyses of practical cases, three design methods were established and classified as “simple”, “medium” and “extensive”. These design methods are valid for both soil behaviour and material behaviour (concrete). A method can be selected in accordance with the risks and the current phase of the project.

antoine.feddema@deltares.nl +31 (0)88 335 7230

It is concluded that the Plaxis Soft Soil Creep model is the most suitable finite elements model for the prediction of horizontal soil deformations. However, the uncertainties in the model factors that are used to account for the 3D effects in a 2D model are still relatively large, since these appear to depend on the model, situation and type of soil.

The committee endorses the established necessity for further investigations in order to arrive at a more precise determination of these model factors. Moreover, it is considered important to acquire a greater insight into the long-term deformation behaviour of soil and the impact on foundations. The committee advises the sectors, clients, knowledge institutes and construction parties involved in this process to set up a practical measuring and monitoring programme for a period of several years.

Further readingCUR report 228 “Ontwerprichtlijn door grond horizontaal belaste palen”, CUR, Gouda, 2010

Finance• Delft Cluster• Rijkswaterstaat• BAM InfraConsutt• Fugro Ingenieursbureau• Movares• Strukton Engineering

Contact:

Deformations of a fly-over bearing

Foundation piles in an embankmentDamaged pile head at the foundation

of a noise screen

94 95

Compensation grouting

in sand

Compensation grouting was developed in order to compensate for settlement during underground construction. Tubes with a diameter of 0.07 m and a length of up to 60 m are installed prior to the underground construction work, together with a monitoring system. The tubes have openings at regular distances covered with rubber sleeves (tubes à manchette, TAMs) through which grout can be injected. Injecting grout into the soil at various locations between the underground construction work and the foundations of the building leads locally to heave that compensates the settlement.

Experimental research on compensation grouting in sand has been performed. Four model test series were conducted to investigate how the shape of the grout bodies made during injection depends on the grout properties, the density of the sand and the way the TAMs are installed. The shape of the grout body affects the necessary injection pressure and whether heave is localised to one injection point or distributed over a wider area. An analytical model was developed that shows the influence of various parameters. More cement in the grout leads to shorter fractures or to no fractures at all. Furthermore, the installation procedure is important. This was the first test series where the installation procedure was included in model tests. Fractures made in sand with a cement-bentonite grout slurry are

adam.bezuijen@deltares.nl +31 (0)88 335 7485

shorter in the laboratory then in the field because the influence of the installation is not taken into account in the model tests. In the tests where the installation procedure was included, the results were more comparable with the results from the field. The installation procedure also influences the injection pressures. The injection pressures were lower in the tests in which the installation procedure was included.

The evaluation of field measurements shows the influence of soil disturbance. Soil disturbance in a layer of sand may lead to a fall in the density of the sand, and compensation grouting in a layer of this kind will lead to lower efficiency. A lot of grout has to be injected to create some heave and long-term settlement is possible.

This PhD project was performed in close cooperation with Cambridge University. Students from Delft University of Technology and from Cambridge University performed the experiments. Data from the Amsterdam North-South metro line were used in this project.

Further readingA. Bezuijen, Compensation grouting in sand, Experiments, Field Experiences and Mechanisms, PhD thesis 2010

FinanceThis is a Delft Cluster product

Contact:

Set-up used in the compensation

grouting experiments

96 97

Grout shapes after injection in sand

for different WCR (water-cement

ratios)

Artist’s impression: Compensation

grouting allows heaving the soil

locally (Picture: Arne Bezuijen)

Piled embankments

In the Netherlands, more than 20 piled embankments have now been built. A piled embankment is a geotechnical composite system consisting of piles, an overlying geo-grid and the embankment fill. The design of the reinforced piled embankment is based on the principle of arching. Piled embankments offer a quick-to-build solution that does not damage sensitive nearby structures and that needs only very limited maintenance. For several projects, piled embankments would have been a good solution but they were not used since no Dutch design standard was yet available. The available foreign design models generated major variations in calculation results. Which basic assumptions apply? What is the appropriate design method? These discussions between contractors and principals frequently took too much time in the tender phase.

The CUR 226 task group ‘Piled Embankments Design Guideline’ recently published the guideline for Piled Embankments. Deltares chaired this task group and contributed to the analysis of existing design methods and to the implementation of parameter studies and the comparison with finite element analysis. On the basis of all these studies, the Dutch guideline adopted major parts of the German EBGEO guideline, and it adapted and extended these in the light of Dutch conditions. For example, clear rules relating to the determination of the traffic load were re-defined, a safety philosophy was defined that matched the Dutch safety approach, and several constraints were determined.

In addition, the calculation results for the existing design models were compared with monitoring results from field studies. Deltares contributed to several of these monitoring projects, like the monitoring programme in Houten for the first piled embankment below a Dutch railway. Among other things, the new model for determining the traffic load on the piled embankment was found to concur with the measurements in Houten.

suzanne.vaneekelen@deltares.nl +31 (0)88 335 7287

In parallel with the design guideline, a software tool has been developed. MPiledRoad is available free of charge. This tool can be used to design the centre-to-centre distance and the length of the piles in combination with a reinforcement in the embankment. Both the Dutch and the German guidelines are available in MPiledRoad.

Now that the Design Guideline is available, the development of this promising concept for piled embankments will continue. Deltares has developed a test set-up for laboratory experiments. The main purpose was to understand the arching principle better, and to make it possible to finally optimise the design guideline. A series of experiments in conjunction with four suppliers generated promising results.

FinanceThis is a Delft Cluster product

Contact:

Model test piled embankment

Arching in pile mattress system

Reconstruction highway A2 near

Beesd (Photo: C. Brok, Huesker)

98 99

BioGrout

Soil in river deltas is often unconsolidated and the construction and maintenance of infrastructure and buildings can be a major issue. BioGrout, one of the processes developed as part of the Deltares SmartSoils concept, is an innovative technology for the in-situ strengthening of unconsolidated sediments using micro-organisms.

In the BioGrout process, loose sand or gravel is converted into stone by injecting a dedicated mixture into the sub-surface which stimulates micro-organisms to catalyse chemical reactions, leading to the precipitation of calcium carbonate (CaCO3) crystals. These crystals form bridges between the existing grains, enhancing the strength and stiffness of the material. The process can be repeated and reversed if necessary. Strength and stiffness can be controlled: more CaCO3 leads to more strength, while permeability does not decrease significantly. BioGrout enables the in-situ treatment of soils, even underneath existing buildings and infrastructure, without interfering with exploitation. The soil stabilisation technique prevents liquefaction, reduces infrastructure settlement and enhances resistance to the erosive forces of water flow. The reactive characteristics of BioGrout are also being investigated in the application of reactive barriers in groundwater treatment.

The first version of BioGrout was developed between 2004 and 2009 in collaboration with Murdoch University, Delft University of Technology, Volker Staal & Funderingen and the French building contractor, Soletanche Bachy. This process used urea and calcium chloride, which were injected into the ground together with laboratory-grown micro-organisms. Deltares launched the development of an improved version in 2009: BioGrout 2nd generation, which uses naturally-occurring micro-organisms. These are dosed with calcium acetate and calcium nitrate to make them grow and multiply more quickly, producing the calcium carbonate “cement” and nitrogen gas as a by-

hans.groot@deltares.nl+31 (0)6 3072 5867

wouter.vanderstar@deltares.nl+31 (0)88 335 7269

product. The process is cheaper and more sustainable, although at present more time-consuming.

In a laboratory setting, 100-litre sand columns were flushed with calcium substrates in order to induce strengthening by carbonate precipitation as a part of the proof of principle. This resulted in better understanding and control of the microbiological processes. Strengthening was achieved but the focus is now on speeding up the process. Relevant geo-engineering parameters and empiric correlations between quantities of calcium carbonate and mechanical parameters were determined for use in design calculations. A transport model was set up for the BioGrout process. The technical durability of BioGrout was studied. A Life Cycle Assessment was performed to establish a picture of the environmental impact of the BioGrout process.

In collaboration with the Delft University of Technology, a study was performed of the feasibility and process design of the production of calcium nitrate and calcium fatty acids as a substrate for the biogrouting process from industrial waste streams (pig farm waste and glucose). For this study, Wouter van der Star and Leon van Paassen received the Leo Petrus Innovation Trophy and Leon van Paassen received the Young Member Award 2009 of the ISSMGE.

Further readinghttp://www.deltares.nl/en/knowledge-and-innovation/innovative-programmes

FinanceDeltares & Water Innovatie Rijkswaterstaat (WINN)

Contact:

SEM picture of biologically formed

calcite crystals on sand grains

100 101

Sand column in the laboratory

backgroundStructuring and planning help to safeguard the sustainable use of space in deltas. The basic assumption for Deltares is that the geo-ecosystem determines use options and quality in the long term and therefore that it provides the direction for spatial design and structuring. An important precondition for sustainable structuring is a match between the design and the dynamics of the system. In addition, society’s requirements are not static. The system diagram for Spatial Development provides an overview of the relevant factors.

The opportunities and limitations of the physical system, as well as social requirements, play an important role and they are shown as the input for the system. At the top, we see the support and direction that Deltares can provide in this process, such as risk analysis, assessment methods and instruments, valuation instruments and scenario studies. The outcomes of interest on the right include climate robustness, sustainable use and spatial quality. These three outcomes constitute three perspectives that can be used as frameworks for the assessment of spatial structuring (such as spatial design and planning) and

scopeThe subsurface, geotechnical and soil environmental quality, and groundwater and

surface water systems are literally the foundation of sustainable life in the delta. Our

understanding of this physical system must be properly folded into spatial planning

processes by contributing the relevant information at the right time and in the proper

way. Here, the human sciences are crucial rather than technical disciplines.

they complement each other. They are at the root of the three road maps in this theme.

This theme is a relatively new field of interest for Deltares, and is currently “under construction”. All the research lines are at the start of their lifecycle. The subjects for the four road maps are:• Climate adaptation, water and spatial planning; • Spatial quality and research by design; • Methods and instruments for integral spatial development

processes;• Marine and land spatial planning.

Deltares makes knowledge available in the form of products that can support this process:• Valuation tools• Assessment methods and tools• Scenario studies• Risk analyses

Opportunities and limitations of the physical system

Demands from the social system

Climate robustness

Sustainable use

Spatial quality

Spatialdevelopment

102 103

Integrated spatial development

Bridging Boundaries

Processes in water management operate on different scales, both in space and in time. Spatial scales vary from global – changes resulting from global warming – to local – water balances in a municipal area. Time scales vary from many years for slow processes such as the diffusion and dispersion of contaminants in groundwater, to a few days for highly dynamic processes such as river discharges to sea.

Scale selection is crucial in a policy analysis process. The adoption of a particular scale in space and time, as well as the level of aggregation, largely determine the types of problem that can and will be addressed, the types of solution that can be found, and the effects that will be evaluated. Scale is not politically neutral. Scale choices have a strategic value because the selection of scale may – intentionally or unintentionally – favour certain stakeholders at the expense of others. Policy analysis processes often involve many actors with different (or even conflicting) interests at different scales, and the selected scale will favour actors whose problem or interests becomes manifest at the selected scale. There is no such thing as the ideal scale because all scales have advantages and disadvantages, not only for actors with specific interests but also at a more

sonja.karstens@deltares.nl+31 (0)88 335 7488

general project level. Scale choices therefore entail dilemmas and difficult trade-offs. The issues under discussion were studied on the basis of two cases: the Long-Term Vision of the Scheldt Estuary and the Water Shortage Study of the Netherlands.

The study in this thesis showed the importance of scale choices for the field of policy analysis. Policy analysis results are sensitive to scale, and so scale choices are relevant and important. The making and handling of scale choices involve many dilemmas and, without a careful approach, there are many pitfalls. Moreover, the thesis showed how scale choices have specific effects on the content and the process of policy analysis. The construction of system diagrams generates an insight into the variables that are taken into account, the exogenous factors and the options. The construction of actor analysis diagrams shows which actors are included or excluded, and whether they feel dedicated or are considered critical. These specific effects are, where possible, used to generate guidelines that support policy analysis design and that help to think through the implications of scale choices.

Finally, the tool presented in the thesis to make scale choices a subject of discussion can also help policy analysts to address other fundamental issues that are usually present below the surface but are hardly ever out in the open, such as power relationships, different interests and hidden agendas. When discussing the options for scale choices, a seemingly harmless and substantive subject, the actors involved may be tempted to reveal a little more about their thinking and strategy.

Further readingS. Karstens, Bridging boundaries, Making scale choices in multi-actor policy analysis on water management, PhD thesis, TU Delft 2009

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2030

2010

Broad range of options: more optimisation possibilities

Ambitious farreaching vision

Possibilities forconsensus buildingEcological concerns

Sense of urgency Economic concerns

Tangible overseeable vision Action ability: results in

the short term

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Tension bow Long-Term Vision

Western Scheldt

Spatial scale choices in Western

Scheldt Vision

Bridging boundaries

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Integral spatial approach to

coastal expansion opens up

key issues

The Dutch Delta Programme is moving towards implementation. Programmes and projects are being prepared for different themes and target areas. For one of those areas, the Holland Coast, Deltares surveyed coastal expansion using an integral research-by-design method.

In its report “Working together with water” (2008) the Delta Committee proposed a seaward expansion of the sandy coast during the next 50 to 100 years by supplying large quantities of sand to the present coastline. An intervention on such a scale and extending over such a long time raises many issues. The key issues were identified in four workshop sessions involving all the relevant disciplines in one research-by-design project.

Experts on morphology, hydraulics, geo-engineering, ecology, planning, management and policy presented their key disciplinary knowledge relating to coastal zone expansion. The exercise was like tipping up a toolbox and explaining which tools are useful for different situations. It is a quick way of sharing

oswald.lagendijk@deltares.nl +31 (0)88 335 7707

knowledge and making sure that everybody is at the same level in terms of relevant information. With direction from landscape architects, small interdisciplinary teams visualised new concepts and ideas on maps, in drawings or profiles, and tried to integrate different disciplines. The time between the sessions was used to dig up detailed information about specific subjects.

One of the drivers for coastal expansion could be the possibility of urban development. At first glance, this looks like an attractive option for the densely populated Randstad. However, there are several major constraints. First of all, new coastal urban areas do not solve the actual socio-economic problems in inner cities of the Randstad. Indeed, it could even exacerbate them. Secondly, the nature and landscape values characteristic of a coastal area will be adversely affected by new urban development. And thirdly, further seaward urban expansion along the cities and villages now on the waterfront will reduce current promenades to backdrop locations. An alternative to coastal expansion is urban renewal in seaside towns and the acceptable urbanisation of the coastal defence line itself. This requires innovations and adaptations in terms of both construction and regulations.

In economic terms, coastal expansion as a strategy seems justified in several cases, but not all. The cost of ‘new’ land per square metre will be higher than in the non-built-up areas in the Randstad. The new land is likely to be a dune area with no sea defences and which is not easily accessible from the mainland. This makes investments in real estate less appealing, raising the question of whether coastal expansion is a sound investment in terms of current national socio-economic standards. Major national projects like this probably need new financial concepts.

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Dynamic coastal expansion using the

morphological forces of nature (from

Nota Ruimte 2004)

Controlled and directed expansion

allows accelerated natural and

artificial growth, determined by the

use of hard materials like dams (from

Nota Ruimte 2004)

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Modelling coastal

vulnerability

This research focuses on the vulnerability of societies in low-lying coastal and delta environments to tropical cyclonic storms and floods. There are hardly any models that explore vulnerability in various planned and unplanned conditions. The Andhra Pradesh Cyclone Hazard Mitigation Project designed and implemented an Expert Decision Support System (EDSS) that links coastal vulnerability to integrated coastal zone management (ICZM). The interpretation and critical examination of the model generated new knowledge about the design of a model of this kind, and about the use of the results to reduce vulnerability through planning.

The fundamental idea underpinning the EDSS is that, in order to determine the impact of a cyclonic disaster on coastal society, the structure and functioning of this society needs to be modelled first with ‘normal’ conditions. Only by understanding the dependencies between the use of land, its resources, socio-economy and environmental conditions, is it possible to simulate the impact of a disruption of these dependencies by a cyclone. The model therefore captures the annual economic and environmental conditions of a coastal area with and without a cyclone. Vulnerability is then calculated as the difference in assets and income in the area for the two years modelled. The model was applied to two different deltas: the Godavari Delta in India and the Red River Delta in Vietnam. Both exercises showed how vulnerability changes as a function of physical and socio-economic conditions. The application of the model to the Godavari Delta confirmed that reducing vulnerability to cyclonic storms requires a broader set of measures than is usually considered by disaster managers. The model illustrates not only the need for flood protection and early warning, but also the need for measures that reduce sensitivity and enhance the resilience of households, like diversifying cropping patterns and broadening the economic basis. Flood protection, early warning and evacuation measures do reduce the number of deaths, but

marcel.marchand@deltares.nl +31 (0)88 335 8558

they cannot prevent wind damage, which still accounts for approximately half of total damage. This insight was possible due to the inclusion of wind hazard as an inextricable part of the cyclone hazard and due to the link with damage to household livelihoods.

The research showed that the differential character of vulnerability originating from inequality in income is essential in order to link it to planning issues. The research proved that modelling coastal vulnerability is possible and useful for the mainstreaming of disaster management into sustainable coastal development. The model’s main contribution comprises three innovations:• the modelling of the entire impact chain, from hazards to

consequences, including exposure, sensitivity and resilience;• the integration of hazards and the human-environment

system, enabling explorative analyses of ‘typical’ disaster management measures, as well as land use planning and environmental management measures;

• the model’s ability to quantify differential vulnerability at the household level, enabling the analysis of measures targeting critically vulnerable groups.

Further readingMarcel Marchand, Modelling coastal vulnerability – Design and evaluation of a vulnerability model for tropical storms and floods, PhD thesis TU Delft 2009

Contact:

A cyclone shelter on the coast of

Andhra Pradesh (India)

Screenshot showing the application

of the model to Andhra Pradesh

(India)

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Mitigating flood impact by

splitting up polders

River and coastal floodplains are often protected by vast systems of connected embankments. About 55% of the Netherlands is protected in this way with some 3600 km of primary water defences. The level of protection is probably the highest in the world, and annual mean flood risks are low. Nevertheless, in the event of a major flood, the consequences would be unacceptable. So consideration needs to be given to whether, and how, the consequences of floods can be reduced in a cost-effective way. Splitting up large polder areas into smaller sections – ‘compartmentalisation’ – would reduce the area vulnerable to flooding, and therefore mitigate economic damage, the number of people exposed and the fatality risk.

We conducted a policy analysis for the national authorities in order to establish whether, where and in which conditions the further compartmentalisation of the country would be desirable. The reduction of flood risks is a complicated task in a country as densely populated and intensively used as the Netherlands. This means that no simple answers can be given without glossing over nuances. Nevertheless, we shall share our main findings without dwelling on details.

nathalie.asselman@deltares.nl+31 (0)88 335 8527

frans.klijn@deltares.nl+31 (0)88 335 8224

• Compartmentalisation is a proven concept for reducing the consequences of disasters in many risk situations.

• It can effectively mitigate the consequences of flooding in terms of damage done and the number of people affected.

• From a narrow economic perspective, it is cost-effective in only a few cases because of the high protection standards maintained in the Netherlands.

• Compartmentalisation is most effective in reducing the consequences of floods in combination with other measures such as a downstream outlet in a river, the differentiation of protection levels (better protection for urban areas than for the countryside), and evacuation planning.

Although flood prevention remains the main objective of the flood risk management policy in the Netherlands, this study of compartmentalisation had a significant effect on awareness among policymakers that the consequences of a flood – however rare – may be unacceptably high, from both the societal and political point of view. Furthermore, it was not so much the economic damage – running into billions of euros – but rather the possible number of fatalities that rang alarm bells. In this sense, our study has triggered a debate about the question of whether a more fundamental statement is needed about the maximum acceptable consequences, specifically in terms of number of fatalities.

Further readingKlijn, F., Asselman, N., Van der Most, H. (2010) Compartmentalisation: flood consequence reduction by splitting up large polder areas. Journal of Flood Risk Management, 3 (2010) 3-17

FinanceRWS TO-program

Contact:

Centuries of land reclamation

have led to an intricate network

of embankments, serving as

compartmentalisation dikes

Flood area in the southwest

Netherlands during the 1953 disaster,

showing the impact of former flood

defences

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Reconstructions Wadden Sea AD 800

and AD 1500

The morphological

development of the

Wadden Sea

Since 1978, the Netherlands, Germany and Denmark have coordinated their activities for the comprehensive protection of the Wadden Sea. For a proper appreciation of the current quality of the Wadden Sea system, a clear understanding of its development over time is essential. In 2008–2009, over 115 scientists from the Netherlands, Germany and Denmark collaborated on the Quality Status Report 2009. Deltares prepared a thematic report on morphological development during the Holocene, and more particularly over the past 500 years.

The reconstruction of the entire Wadden Sea of AD 1500 shows a predominantly natural Wadden Sea. From that time on, there was increasing human interference with the Wadden Sea system. In broad terms, the Wadden Sea coastal configuration has remained much the same over the past 500 years, as is apparent from the similarity of the reconstructions. For example, the area of tidal flats and island size is largely comparable in the reconstructions of AD 1500, 1850 and 2000. This suggests that the Wadden Sea

albert.oost@deltares.nl +31 (0)88 335 7143

ane.wiersma@deltares.nl+31 (0)88 335 7176

system as a whole is, morphologically speaking, characterised by a kind of dynamical equilibrium during this period.

Looking more closely, however, it emerges that, everywhere along the mainland, coastlines have become straighter and shorter, partly due to natural sedimentation and erosion, and partly because of human interference, which reached very significant proportions in the 20th century. In addition, all the barrier islands (which are mainly sandy) have changed to some extent in form, and some (e.g. Buise) have disappeared. The coast is clearly bearing the full brunt of North Sea hydrodynamics and it will continue to do so. Comparison of the changes on all the barrier islands through time might provide clues about what to expect in the future as a result of expected climate changes.

There is a marked difference between the development of the east-west trending Wadden Sea of the Netherlands and Niedersachsen and the north-south trending Wadden Sea of Schleswig-Holstein and Denmark. Whereas the first area is quite stable, the northern Wadden Sea area has undergone strong drowning and land loss (e.g. the Halligen and intertidal areas in front of the Danish barrier islands). It is not completely clear what causes these differences.

These reconstructions of the entire Wadden Sea provide a first overview of the various morphological developments in the Wadden Sea system over time: from a fully natural system around AD 800 to a human influenced system by AD 2000. We therefore suggest using the reconstructions as a “morphological reference guide” in attempts to achieve a near-natural situation.

Further readinghttp://www.waddensea-secretariat.org/QSR-2009/09-Geomorphology-(10-03-09).pdf

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Photo: Flickr CC by Noema

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EditorsJurjen van Deen, Margriet Roukema

Translation Pete Thomas, Alkmaar

DesignONTWERPERS DIE MEEDENKEN.NL

Printing3L Drukkerij BV, Rotterdam

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