3 coastal landscapes in the netherlands · 2016-09-22 · workshop 1: challenges with rejuvenation...

3 coastal landscapes in the Netherlands

Reconstruction c. 800 A.D.

Workshop 1: Challenges with rejuvenation and dynamics in inland and coastal dunes

• Introduction on the actual dynamic coastal management in the

Netherlands and the ecological implications on landscape level Evert Jan Lammerts, Staatsbosbeheer/OBN

• Introduction of restoration of inland dunes Eva Remke, Stichting Bargerveen

1 Noordzee 2

5

eiland 3

getijdebekken 6 getijdebekken 4

To\from 1 2 3 4 5 6 1 + + + NVT NVT 2 + + NVT + NVT 3 ++ + ++ + ++ 4 ++ NVT + NVT + 5 NVT + ++ NVT + 6 NVT NVT + + ++

Model of a Wadden Sea island

Main components : 1. Island head (25-50) 2. Closed dune bow complex (50-400) 3. Washover complex (50-100) 4. Island tail (25-50) 5. Beach and foreshore

Hypothetical balance in the mainland coast

A model of landscape processes along the

Delta coast

Van Haperen 2014

From a natural to an engineered systeem

Dominant events (measures) … (1) Basin enlargement by peat

cuttings and floodings (< 1900)

(2) Basin reduction by impoldering and closing Zuiderzee (1932) and Lauwerszee (1969)

(3) Stabilization of basin and

Wadden Sea islands by the construction of dikes, (concrete and sandy) and coastal management (since 1990 mainly by sand nourishments)

Lucas Jansz Waghenaer (1584) ‘Spieghel der Zeevaerdt’ 7/25/2016 (Edwin Elias)

Before closure After closure 7/25/2016 (Edwin Elias)

Dominant events (measures) … (1) Basin enlargement by peat

cuttings and floodings (< 1900)

(2) Basin reduction by impoldering and closing Zuiderzee (1932) and Lauwerszee (1969)

(3) Stabilization of basin and

Wadden Sea islands by the construction of dikes, (concrete and sandy) and coastal management (since 1990 mainly by sand nourishments)

From a natural to an engineered systeem

7/25/2016 (Edwin Elias)

From a natural to an engineered systeem

Dominant events (measures) … (1) Basin enlargement by peat

cuttings and floodings (< 1900)

(2) Basin reduction by impoldering and closing Zuiderzee (1932) and Lauwerszee (1969)

(3) Stabilization of basin and

Wadden Sea islands by the construction of dikes, (concrete and sandy) and coastal management (since 1990 mainly by sand nourishments)

7/25/2016 (Edwin Elias)

From a natural to an engineered systeem

Dominant events (measures) … (1) Basin enlargement by peat

cuttings and floodings (< 1900)

(2) Basin reduction by impoldering and closing Zuiderzee (1932) and Lauwerszee (1969)

(3) Stabilization of basin and

Wadden Sea islands by the construction of dikes, (concrete and sandy) and coastal management (since 1990 mainly by sand nourishments)

Coastal management in the Nederlands

(Edwin Elias)

Volume changes in the coast 1990 – 2005 (million m3)

> 5

1 - 5

-1 - 1

-1 - -5

< -5

including nourishments: nourished: 102.9 coastal zone: -214.5 basins: 54.7 Total: -159.8

upper shoreface / beach / frontal dunes: natural -41.5 nourished 118.6 Total: 77.1

• Big losses along the Wadden Sea coast

• Sedimentation in the Waddenzee

• A stable, even expanding, mainland coast incl. Dutch mainland coast, incl. islands

• Sand redistribution

on the Voordelta (Zeeland)

(Edwin Elias)

Rijkswaterstaat 13 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2002

How sand nourishment works

Rijkswaterstaat 14 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2003

Rijkswaterstaat 15 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2004

Rijkswaterstaat 16 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2005

Rijkswaterstaat 17 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2006

Rijkswaterstaat 18 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2007

Rijkswaterstaat 19 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2008

Rijkswaterstaat 20 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2009

Rijkswaterstaat 21 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2010

Rijkswaterstaat 22 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2011

Rijkswaterstaat 23 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

2012

Rijkswaterstaat 24 Consultatie Kustlijnzorg – Meerjarenprogramma 2016-2019

In 4 years 0 to 150 m landward shift

In 4 years 300 to 500 m landward

shift

The Sand engine (Zandmotor)

Sep 5, 2011 March 20, 2012

July 2, 2012 Oct 31, 2012

(Edwin Elias)

Dynamic Preservation 26

The Sand engine : is it really a unique experiment?

May 16, 2013 Oct 31, 2012

This is Ameland!!!

(Edwin Elias)

Concepts for restoration and planning: focus on the “right” temporal and spatial scales

Examples from Schiermonnikoog and Terschelling

Schiermonnikoog

Schiermonnikoog situation 1959

stuivende duinen

onbegroeid strand

vergrast duin

zandige kopjes in kwelder

jonge kwelder

oude lage kwelder

vergraste kwelder

knopbiesvegetatie

Schiermonnikoog nowadays stuivende duinen

onbegroeid strand

vergrast duin

zandige kopjes in kwelder

jonge kwelder

oude lage kwelder

vergraste kwelder

knopbiesvegetatie

Restoration Washover complex

Schiermonnikoog with washover complex

stuivende duinen

onbegroeid strand

vergrast duin

zandige kopjes in kwelder

jonge kwelder

oude lage kwelder

vergraste kwelder

knopbiesvegetatie

Model results showing decrease in the fresh water body (A) as a consequence of a withdrawing coastline after sea level rise (1 meter).

Development of the fresh water body influenced by sea level rise and sand nourishment (example from south-Texel)

Model results showing increase in the fresh water body (C) as a consequence of an expanding coastline after sea level rise (1 meter) combined with an expanding coastline by sand nourishment over a width of 800 meters on the adjacent beaches.

Uit: Stuyfzand et al 2014

Paal 15-20

CLOSED DUNEBOW COMPLEX TERSCHELLING

Allowing natural erosion and sand blowing

Moving sand between 1997 en 2008 (analysis data by Bas Arens)

: erosie : sedimentatie

c. 1990

Habitats on model Schiermonnikoog

Is a natural landscape the best garantuee for coastal biodiversity ?

Key-factors for the future

• On the long term, maintaining many characteristic and threatened dune species is possible only when applying Nature management which is in phase and space with natural geomorphological and ecological processes.

• Dynamic coastal management probably increases coastal resilience and may increase safety while decreasing the need for sand nourishments.

Ecological strategies for coastal management

1. Dynamic coastlines with natural sedimentation and erosion : freely moving sand and salt/fresh water being in phase with the

periodicity and spatial patterns of large scale natural sedimentation and erosion processes!

2. Within safety boundaries ….. using natural sedimentation and erosion of sand as management tools, on partial landscape scale

3. Whén sand nourishments are needed to maintain the coastline, there are two options :

1. natural succession, 2. periodically active management (e.g. sod-cutting, mowing, grazing, artificially

stimulating sand-blowing, water management).

Natural and semi-natural management strategies on landscape and habitat level along the Dutch coastal areas

Discussion items on management strategies along the European (or national ?) coastlines :

– Do we know enough about the landscape settings

and the corresponding natural processes ?

– Is there an adequate picture of the main antropogenic influences (first of all coastal defense) ?

– Do we have the knowledge to choose the “right” spatial and temporal scales of nature management ….

– …. in other words :

• which criteria indicate when to act on landscape level and when on habitat level ?

• which criteria indicate when to focus on influencing lifespans of individual species and when to act on successional change of ecosystem level ?

– What can we do now on the habitat level ?

The End