results of a trilateral expert groupresults of a trilateral expert group. Schleswig-Holstein State Ministry for Agriculture, Environment and Rural Areas Jacobus Hofstede 08/10 –

Schleswig-Holstein State Ministryfor Agriculture, Environment

and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden

Towards a trilateral research agenda

Climate change and the need for sand:

results of a trilateral expert group


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Main challenges for the Wadden Sea1. Climate change and sea level rise

Trilateral Governmental Conference for the Protection of the Wadden Sea (Sylt)

2. Sustainable development

3. Awareness

Jacobus Hofstede


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Country Area (km2) Population

NL 6.294 1.250.000

GER 10.634 2.200.000

DK 600 100.000

Sum 17.528 3.550.000

““Human resources”Human resources” Esbjerg

Hamburg

BremenGroningenLeeuwarden o o

o

oo


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Expert group Coastal Protection and Sea Level RiseExpert group Coastal Protection and Sea Level Rise

CPSL I (1997 – 2001)Common knowledge base geomorphology, biology und coastal protectionAnalyses and evaluation of climate change impactsScreening of possible BEP-solutions for a sustainable coastal protection

CPSL II (2001 – 2005)Analyses and evaluation of seven selected BEP-solutions for two hydro-morphological scenarios

CPSL III (2005 – 2009)Feasibility of coastal spatial plans that consider climate changeFeasibility of a study on sand replenishment to balance sediment deficits

Merit: “investigate the possible effects of enhanced sea level rise and, on the basis of such an investigation, develop proposals for future integrated coastal defense and nature protection policies”


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden

Towards a trilateral research agendaCPSL I CPSL II CPSL III


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Negative feedback loops:

- Tidal flats (salt marshes)

- Tidal gullies

Depending on

sediment availability!

CPSL I


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Jacobus Hofstede


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Jacobus Hofstede

CPSL I


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


CPSL I

Jacobus Hofstede


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Spatial planning:

Coastal regional plans that include buffer zones and hazard zones constitute environmentally friendly non-technical options to control coastal risks.

- Buffer zones: reserve for future CP measures and for natural dynamics

- Hazard zones: user restrictions / building restrictions to reduce damages and improve public awareness

Sand replenishment:

Sand replenishments constitute a successful and environmentally friendly option to balance beach erosion during storm surges and to stabilize dunes as flood defences.

Sand replenishments may compensate/diminish the expected sediment deficit in the Wadden Sea resulting from stronger sea level rise.

CPSL II


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


CPSL III

1) to initiate a study on the feasibility of coastal spatial plans that consider

climate change;

2) to investigate the possibilities of a study on the feasibility and effects of sand

nourishment to balance the sediment deficit of the Wadden Sea tidal basins

under increased sea level rise.

For task 1, CPSL was augmented with experts from spatial planning.


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


The role of spatial planning in coastal

risk management is prevention

Aim: avoiding/reducing/controlling

vulnerabilities (damage expectations)

in the lowlands

Coastal risk management aims at

avoiding/reducing/controlling the risk

of flooding and erosion in the coastal

zone

Risk is a function of vulnerability and

probability


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Utilization restrictions in coastal flood-prone areas

In the Regional Plan for RibeCounty, it is specified that new town development behind the Ribe dike must be built with a floor level at least 4.75 m above sea level west of the Bramming – Tønder railway and at least 3.9 m above sea level to the east of it.


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Physical boundaries as basis for spatial planning


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Can the Wadden Sea survive sea level rise?

Sediment is the problem, the challenge and, possibly, the answer!


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden

Towards a trilateral research agendaBP

Jelgersma (1979)


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


10,000 BP 6,000 BP

„Drowning“


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden

Towards a trilateral research agendaBP

Jelgersma (1979)


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


6,000 BP

4,000 BP

2,000 BP

„Stable phase“Jacobus Hofstede


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


-25

0

25

50

75

1850 1900 1950 2000 2050 2100

Years

Sea

leve

l (cm

)

IPCC

Greenland?

Unknown factors: result SLR

Greenland and West Antarctic ice caps ↑CO2 sinks (ocean, tropical forests) ↑NO emissions (ocean floor, permafrost) ↑What happens after 2100? ↑Snow precipitation on Antarctica? ↓Blockung of Gulf Stream? ↓

0,5 - 1,4 m!

Sea level scenarios (1990 – 2100):IPCC (2007): 0.2 – 0.8 mHorton et al. (2008): 0.5 – 1.0 mDelta Commission (2008): 0.9 – 1.3 mGrinsted (2009): 0.9 – 1.3 mVermeer/Rahmstorf (2009) 1.0 – 1.4 m


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Sediment is the problem, the challenge and, possibly, the answer!

The problems: SLR may exceed 0.5 cm/y in the second half of this century

not enough natural sediment input to balance SLR > 0.5 cm/y

real hazard of slowly drowning intertidal flats (world heritage)

no significant landward retreat possible, nor appropriate

The challenges: how to maintain ecological integrity and functionality

how to maintain coastal defence significance of intertidal flats

One answer: improve sediment input (natural / artificial)


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Sylt Declaration 23:… and instruct the Board to initiate a trilateral study on

sustainable solutions to balance the expected sediment deficitson the basis of (14) research questions specified by the CPSL

Sources:How much sediment is needed to counteract particular rates of sea-level rise along the outer coasts and for the Wadden Sea as a whole?

Transport mechanisms:Can import and trapping mechanisms be improved?

Sinks:Where are optimal locations for artificial sediment-deposition to balance sea-level rise in the Wadden Sea?


and Rural Areas

Jacobus Hofstede

08/10 – 12 – 2010, Leeuwarden


Sediment sources:Beyond what water depth should sand preferably be mined for nourishment and is there a regional variation in this depth?How much sediment is needed to counteract particular rates of sea-level rise along the outer coasts and for the Wadden Sea as a whole? Are there functional relationships?Are the available amounts of sand sufficient for the future and which grain sizes are available?What kind of dredging (volumes, form, timing and frequency) results in minimal morphological effects?What kind of dredging (volumes, form, timing and frequency) results in minimal ecological effects?

Transport agents:Can import and trapping mechanisms be improved?Quantification of (natural) sediment sources?Can main/major sediment transport mechanisms, routes and volumes be defined?

Sinks:Where are the optimal locations for artificial sediment-deposition to balance sea-level rise in the Wadden Sea?What are the morphological impacts?What are the ecological impacts?What happens to the deposited sediments?Which grain size and quantities are optimal?What kind of nourishment techniques should be used?

Documents

results of a trilateral expert groupresults of a trilateral expert group. Schleswig-Holstein State Ministry for Agriculture, Environment and Rural Areas Jacobus Hofstede 08/10 –