Coupling terrestrial and marine datasets for coastal hazard assessment and risk reduction in changing evironments A EUR-OPA Major Hazards Agreement Project

S18A CERG Subsession: Methods for landslide hazard and risk assessment

Mauro Soldati1, Olivier Maquaire2, Anton Micallef3, Federica Foglini4, Alessandro Pasuto5, Mariacristina Prampolini1, Chiara Tonelli1, Stéphane Costa2, Christophe Delacourt6, Michel Jaboyedoff7

1Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Largo S. Eufemia 19, 41121 Modena, Italy. Corresponding author: soldati@unimore.it 2 Laboratoire de Géographie et Environnement, LETG-Caen GEOPHEN, UMR 6554, Université de Caen Basse-Normandie, Esplanade de la Paix, 14032 Caen, France 3 Euro-Mediterranean Centre on Insular Coastal Dynamics (ICoD) - University of Malta, Msida, MSD 2080, Malta 4CNR – Istituto di Scienze Marine, UOS Bologna, Via Gobetti 101, 40128 Bologna, Italy 5CNR-IRPI Padova, Corso Stati Uniti 4, 35127 Padova, Italy 6 Institut Universitaire Européen de la Mer (IUEM), Domaines Océaniques - UMR 6538, Place Nicolas Copernic, 29280 Plouzané, France 7 Faculty of Geosciences & Environment, Quartier UNIL-Sorge, Bâtiment Amphipôle 363, CH-1015 Lausanne, Switzerland

INTRODUCTION The main objectives of the EUR-OPA Agreement of the Council of Europe are to provide closer cooperation among member states in order to ensure better prevention and protection in case of disasters and to develop new methodologies and tools for efficient risk management. This poster aims to show the first results of the Project “Coupling terrestrial and marine datasets for coastal hazard assessment and risk reduction in changing environments”, managed by the Euro-Mediterranean Centre on Insular Coastal Dynamics (ICoD) in collaboration with the European Centre on Geomorphological Hazards (CERG). The Project foresees also the participation of Università di Modena e Reggio Emilia, Université de Caen Basse-Normandie, CNR-ISMAR Bologna and CNR-IRPI Padova. This Project aims at linking and integrating terrestrial and marine datasets along the coastlines of Malta and Lower Normandy (France). The investigations carried out so far have contributed to a better definition of the kinematics of active landslides that may determine risk situations.

OBJECTIVES OF THE PROJECT

Acquiring new data on submarine landforms and processes along the Malta and Normandy coastlines;

Integration and coupling of existing and the newly acquired terrestrial and submarine datasets; Definition and assessment of the relationships between terrestrial and submarine morphological

features focusing on landslide processes ; Monitoring of coastal landslides; Acquisition of necessary knowledge to define methods to perform landslide monitoring offshore; Improvement of existing hazard maps taking into account issues related to climate change (sea-

level change, more frequent extreme meteorological events etc.); Definition of protocols which can be utilised in other coastal environments for risk reduction and

resilience improvement.

NW COAST OF MALTA

REFERENCES

A) Geographical setting of the Maltese archipelago B) the study area and (C,D) location of the landslide monitoring sites. E) Geomorphological map of the NW coast of Malta 1:7500 by Devoto et al., 2012.

Wha

t’s u

nder

the

sea

leve

l?

F

F) Bathymetric data (DTM 2 m resolution) acquired using the interferometric system Swathplus (ABT Marine). G) Morphometric analyses (planform and profile curvature are shown, but slope and aspect were also performed) permitted to highlight the

G IL-PRAJETT IL-QARRABA

First attempt to couple land & sea

The following investigations have been carried out so far: bathymetric (and backscatter) survey off the NW coast of Malta

performed by the ABT Marine in may 2012 manual and morphometric analysis of bathymetric data preliminary manual analysis of backscatter data aerial-photo interpretation and field survey monitoring of coastal landslides.

Devoto S., Biolchi S., Bruschi V.M., Furlani S., Mantovani M., Piacentini D., Pasuto A., Soldati M. (2012). Geomorphological map of the NW Coast of the Island of Malta (Mediterranean Sea). Journal of Maps, 8(1), 33-40. Mantovani M., Devoto S., Forte E., Mocnik A., Pasuto A., Piacentini D. e Soldati M. (2012). A multidisciplinary approach for rock spreading and block sliding investigation in the north-western coast of Malta. Landslides DOI: 10.1007/s10346-012-0347-3

“Coastline at risk: methods for multihazard assessment” (cf. Mantovani et al., 2012).

Further investigations: continuation of monitoring of coastal landslides; collection and analysis of high resoultion (1 m) LiDAR data; semi-automatic classification of backscatter data (TexAn, FMGT, etc); detailed mapping of the extension of the landslides offshore; outline of the geomorphological evolution since LGM.

Background data from the CERG 2009-11 Project

In the zone of very shallow water, it has been possible to well recognize the presence of rock (limestone) blocks that have been interpreted as the extension of the block slides identified and monitored along the NW coast of Malta. The analyses outlined that coastal landslides have a relevant extension under the sea level (up to 880 m far the coastline). Regarding the sea level variations, recent literature permitted to outline the fluctuations since LGM and this contributed to the hypothesis that these large-scale landslides were possibly triggered in different morpho-climatic conditions, when the sea-level was much lower than at present. The results achieved so far are the base for a more comprehensive coupling of terrestrial and marine datasets.

LOWER NORMANDY (FRANCE)

Active lateral spreads and block slides characterise the NW coast of Malta.

presence of limestone blocks fallen and subsequently slided seaward.

ESTRAN, 14/04/2009

Along the Normandy coast, the research focuses on landslides and storm surges: the landslides studied are falls in hard rocks (cliff falls, debris fall and boulder and rock falls) and slides in soft rocks.

A) Geographical setting of the Normandy and B) the study area

A

B

C) cliff fall; D) aerial view of the Villerville-Cricqueboeuf landslide in 1988.

C D

The reasearch carried out so far includes geomor-phological surveys and LIDAR data interpretation to produce a geomorphological map; geothechnical and geophysical surveys; quantification and evolution of the cliffs through TLS (Terrestrial Laser Scan) with very high resolution; Verification of feasibility and estimation of accuracy of coupling MLS (Mobile Laser Scanning) and bathymetry (multibeam) in order to acquire simultaneous new data on submarine and subaerial landforms.

Mob

ile L

aser

Sca

nnin

g (M

LS) c

oupl

ing

with

Mul

tibea

m

I) Example of merged different submarine and terrestrial datasets under the GIS platform for the Villerville landslide test site.

E) General view of the different devices (MLS coupling with Multibeam) installed on the boat for simultaneous survey (September, 2012)

F) Example of vessel trajectory during bathymetry and MLS acquisitions for one single day in September 2012 from Cap d’Ailly (Varengeville) to Puys (Upper Normandy)

G) Cloud points obtained by MLS (Mobile Laser Scan) from Dieppe to Pourville (Upper Normandy, September 2012)

H) Bathymetry in front of the Ailly Cape obtained by multibeam sounder high-resolution in September 2012

First preliminary results: Once all instruments set up on board (Fig. E), topographic and bathymetric measurements can be done quickly. With good weather conditions, we could obtain information on approx two linear km per hour. For the MLS (Fig. G),we obtained a very good general aspect of landforms. In high density areas (Zoom 1), resolution is better than 10 cm (cf. house). Mmorphological parameters (Zoom 2) can be well observed, even on intertidal areas. Surfaces processes, such as collapse talus, can be observed and quantified in few seconds. For the multibeam survey, the results allow to well observe the bathymetry with a very high resolution (around 20 cm): an important accumulation of blocks of sandstone on the lower shore platform is well detected (Fig. H). These blocks are in relation with the large old rockfall.

Further investigations: continuation of monitoring of coastal landslides; comparison the data acquired by MLS and TLS in the same zones, in order to define their respective resolution and repeatability; verification if the coupled methods (MLS coupling with Multibeam) could become a reliable and rapid technique for regularly monitor the cliff dynamic.

I

G H

F

E

View publication statsView publication stats