Flood protection, Natura 2000 and navigation in the Scheldt estuary: how to combine conflicting interest into a mutual successful management

Prof. dr. Patrick Meire

Ecosystem Management Group

University of Antwerp

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AntwerpenSchelde river350 km longestuarymacrotidal160 km long

Netherlands

Belgium

France

Change in geomoprhology: embankments

From 1000 BP onwards:

150.000 ha embanked

1000 ad

1750 ad

Green: tidal marshes

Yellow: tidal flats

Dark yellow: dunes

Redbrown: Holoceen sands;

brown: coastal peat areas;

Pink: embankments

Antwerpen

Gent

Vlissingen

BELGIUM

THE NETHERLANDS

WESTERSCHELDE

ZEESCHELDE

Changing geomoprhology: deepening

But: an estuary is a system

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agriculture

industry

Morphologyshipping

Channel depth

surfaceHydrodynamics

Sea level rise in combination with morphological changes in the estuary resulted in an amplification of the tides!

Concerns about tidal amplification

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Concerns about increased flood risks

But: an estuary is a system

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agriculture

industry

Morphologyshipping

Channel depth

surface

Hydrodynamics

Concerns about erosion, morphological changes

Tidal marsh of Waarde

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Cox et al. 2003, Continental Shelf Research

But: an estuary is a system

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agriculture

industry

Morphologyshipping

Channel depth

surface

Water quality

householdsBiodiversity andEcological functioning

Hydrodynamics

But: an estuary is a system

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agriculture

industry

Morphologyshipping

Channel depth

surface

Water quality

householdsBiodiversity andEcological functioning

Hydrodynamics

Fresh Brackish Marine

Expected number of species

Concerns about biodiversity

How did we cope with these problems?

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Floods: More infrastructure: SIGMAPLAN

Heigher and stronger dikes

Flood Control Area (FCA)

Floods: More infrastructure: SIGMAPLAN

Floods: More infrastructure: SIGMAPLAN

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SAFETYDuring a storm(6-12-2013)

Overflow dike

FCA –CRT Bergenmeersen

Floods: More infrastructure: SIGMAPLAN

Floods: More infrastructure: SIGMAPLAN

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Model simulation of 100-yr storm surge (Meire et al. 2014 ECSA Bull.)

60 cm80 cm

After all FCA (by 2030)

Sto

rm s

urg

e w

ate

r le

ve

l (m

TA

W)

Distance to estuary mouth (km)

Impact of FCA on high water levels

Floods: More infrastructure: SIGMAPLAN

• Sigmaplan protects agains floods

• BUT

• Does not tackle the cause of increasing flood risk

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Water quality: waste water treatment

Water quality: waste water treatment

Notwithstanding major improvement,

➔ Water quality objectives not reached

➔ Does not take into account the interaction betweenwater column and river bed (historic pollution is notremoved)

➔ Does not take into account nutrient ratio’s whichimpacts algal growth

➔ Does not take into account the biogeochemicalfunctioning of the ecosystem

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Biodiversity protection driven by legislation

EU habitat directive requires compensation of habitat lossin Natura 2000 areas

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Biodiversity protection driven by legislation

• Loss of a tidal marshes for a container terminal is compensated by restoring a former marsh

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Biodiversity protection driven by legislation

It can prevent overall loss of habitat

• Is mainly based on structural aspects

• To maintain the surface of specific habitat types

• To maintain a certain population of specific species

• Mentioned in the appendices of the directives

BUT

• Is the restoration succesful?

• Does it impact estuarine problems?

• ➔ does it lead to desirable futures?

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Biodiversity: designation and management of reserves

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Use of rip-rap

Paul Holmes Strays, Humber estuary

Key message

• Present management is an endless vortex leading tofurther tidal amplification, geomorphological changes and loss of biodiversity and will require more and more management measures to garantuee safety againstfloods and access to the harbour of Antwerp

• A good understanding of the functioning of the system and a “systems diagnosis” is a crucial step to go from a sectorial approach to an integrated approach!

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Key message

A fundamental paradigmashift is necessary. The crucialquestion is no longer, do have human interventions have aneffect on biodiversity, but has loss of habitat andbiodiversity an effect on

▪ The economy

▪ Human welbeing

Nature is not part of the probleem, but part of thesolution!

Restoration driven by functional approach

➔ Requires a different more integrated approach

A move from a structural towards a functional approach, where habitat are designed in such a way that they improvethe overall functioning of the estuary tackling the major estuarine processes

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Bringing things together: towards anintegrated approach

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Towards an integrated approach

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ECOSYSTEM

Properties Functions

SOCIETY

Benefits values

ECOSYSTEM SERVICES

SUPPLY DEMAND

Ecosystem services as a unifying concept requires:

• Quantification of ES == supply of ES

• Understanding the demand of ecosystem services

Bio-physical system

Limitations and opportunities

Supply of ES

What are the Service providing units (SPU)/ Ecosystem service provider (ESP)?

Which and how much Ecosystem Services are delivered by what?

Ecosystem services?

Quantification of the demand for ES

The need for ES is very often not obvious as the link between problems experienced by people and the underlying loss of ES delivered by ecosystems causing the problem is very often not understood!

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Geo-physical system

Demand for

ESS

Limitations and opportunities

Socio-economic system

Supply of ESS

How much of an ES do we need?

Formulating objectives

▪ Safety ➔ floodrisk should be less than 1/4000

▪ Tidal dissipation ➔ tidal amplification should stop

▪ Nutrient removal ➔ load to North Sea must drop

▪ Si delivary➔ should be high enough to prevent Si limitation

▪ Primary production➔ should sustain fisheries

Formulating objectives

▪ maintaining hydromorphology➔minimize dredgingcosts

▪ resilient ecosystem ➔maintain water quality, productivity, recreation, EU conservation objectives

▪ ….

▪➔MUST BE DETERMINED IN A QUANTITATIVE WAY

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Bio-physical system

Demand for

ESS

Limitations and opportunities

Socio-economic system

Supply of ESS

Mismatch?

Where to look?

Where are the bio-physical opportunities

and limitations situated?

Final CO: ➔ Max (surface S1,..Sn; F1,…,Fm)

➔ Habitat quality

H

a

b

i

t

a

t

1

Conservation Objectives (CO)

Species 1

populationSurface S1

habitat quality

density

Function 1

habitat quality

volume

Surface F1unit

Updated SIGMAPLAN

Intertidal marsh creation to solve estuarine problems

Marshes in 1200: ~100 000 ha

Marshes now: ~3260 ha

Marshes by 2030: + 1500 ha

Maintenance

Ketenisse

Marsh restoration

Develop new techniquesFlood Control Area (FCA)

Combining ES

▪ Flood control ➔ water quantity

▪ Biogeochemical functioning➔ water quality

Looking for bundles of ES and new concepts andmanagement measures!

Pilot project Lippenbroek

10 ha of tidal nature developping: May 2008

0

1

2

3

4

5

6

7

7/04 12/04 17/04 22/04 27/04 2/05 7/05

date

level

(m T

AW

)

Schelde (De Plaat)

Lippenbroek

0

1

2

3

4

5

6

7

7/04 12/04 17/04 22/04 27/04 2/05 7/05

date

level

(m T

AW

)

Lippenbroek

Schelde (De Plaat)

0

1

2

3

4

5

6

7

7/04 12/04 17/04 22/04 27/04 2/05 7/05

date

level

(m T

AW

)

Lippenbroek

Schelde (De Plaat)

❖ reduction of tides with 3 meter

❖ No reduction of spring-neap tide variation

Results: tidal range

Water quality regulation

Lippenbroek 16-05-06

0

25

50

75

100

125

150

175

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

time (hour)

oxyg

en

(% s

at)

INFLOW OUTFLOW

Water quality regulation: oxygen delivery

Water quality regulation: Silica delivery

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0

2

4

6

8

10

9 10 11 12 13 14 15 16 17 18 19 20 21 22

time (hrs)

DS

i (m

g/l

SiO

2)

Lippenbroek estuary

Inflow Outflow

DSi (mg/l) 3/7/2006

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Water quality regulation: Silica delivery

Water quality regulation: nitrogen retention

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Yearretention of TDIN: averge 5 kg per tide!

Distance from creek edge (m)

Gro

undw

ater

leve

l (m

TA

W)

Benthic processes

Water quality regulation: nitrogen retentionmechanism

restored marsh | spring tide

Gro

undw

ater

leve

l (m

TA

W)

Distance from creek edge (m)

Water quality regulation: nitrogen retentionmechanism

Natural marsh Restored marsh

Tidally deposited sediment

Historically compacted subsoilTidally deposited sedimentcree

k

sediment

organic matter macropores

high-resolution X-ray CT scanning

Natural marsh Restored marsh

Tidally deposited sediment

Historically compacted subsoilTidally deposited sediment

sediment

organic matter macropores

cree

k

Natural marsh Restored marsh

Tidally deposited sediment

Historically compacted subsoilTidally deposited sediment

sediment

organic matter macropores

cree

k

Bergenmeersen

Polders van kruibeke

FCA Polder van Kruibeke

Inauguration of the “Polders van Kruibeke” June24th 2017

https://vimeo.com/226267624

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Managed realignment

1990 1998

Managed retreat of potpolder Lillo

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Managed retreat Wijmeers

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Is this restoration economically viable?

Polders of Kruibeke

Sigmaplane.g. Polders of Kruibeke

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7171

Polders of Kruibeke

Step 1: What are the effects of the project

100 M€ (600 ha) (until 2100 ) 237 ha - 600 ha

640 m³/y (annual productivity)

N burial: 7.8 tonN/y

Denitrification: 32 tonN/y

5,000 tonCO2/yP burial:

0.5 tonP/y

21 tonPM10/y

FLOOD PROTECTION FOOD PRODUCTION: LIVESTOCK FOOD PRODUCTION: CROPS

WOOD PRODUCTION AIR QUALITY REGULATION: FINE DUST CAPTURE

WATER QUALITY REGULATION CLIMTE REGULATION: CO2 SEQ.

Boerema et al. 2015, Terra et Aqua nr. 41Project for the International Association for Dredging Companies (IADC)

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Polders of KruibekePolders of Kruibeke

Step 2: Cost-efficient project (benefits>costs)?

Without ES benefits

€

-200.000.000

-100.000.000

0

100.000.000

200.000.000

Costs Benefits Sum Costs Benefits Sum

Without project With project

Investment

Maintenance (100y)

Food (100y)

Flood (100y)

Sum

+additionalES benefits

€

-200.000.000

-100.000.000

0

100.000.000

200.000.000

Costs Benefits Sum Costs Benefits Sum

Without project With project

Investment

Maintenance (100y)

Food (100y)

Flood (100y)

Additional ES benefits (100y)

Sum

Food

Floodsafety

Boerema et al. 2015, Terra et Aqua nr. 41Project for the International Association for Dredging Companies (IADC)

INTEGRATE THE PEOPLE

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Key message

• Estuarine restoration is much more than just making a new habitat.

• The integrated approach requires the understanding of the whole system functioning and insight into the trends of the major driving forces.

• Hydrodynamics, morphology and ecology are closely linked and

• Objectives should be formulated in a more integrated way (not just biodiversity)

• Move towards a process based restoration! Not for the ecologist but for the ecology

Conclusion

• For the Schelde case, the concept of ES has

• Facilitated the communication between different stakeholders

• Allowed a more integrated approach

• To formulate ES objectives for different parts of the system and different users

• ➔ the concept has impacted the outcome of the project!

Communication as a crucial issue

• The benefits and added value of the project should becommunicated to the stakeholders

• ES makes communication about ecosystem basedadapation much easier than biodiversity as such

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Please come and visit the Scheldeit would be a great pleasure to guide you around

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FOR MORE INFO: WWW.SIGMAPLAN.BE

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Thanks for your attention