Floodplain reconnection in the Vallei van de Grote Nete, Belgium

General

National Id

Belgium_02

Site name

Grote Nete between Oosterlo and Nijlen

Summary

This scheme is part of the Sigmaplan programme, which is a long-term large-scale programme in Belgium aiming to improve flood storage of the Scheldt catchment. This particular scheme, on the Grote Nete, reconnects the river to its floodplain, which is currently isolated by dykes along both river banks. In the middle reach of the catchment, ‘controlled water storage areas’ will be developed, where a connection between the river and floodplain will be introduced but controlled. In the upper and lower catchment, free connection between the river and floodplain will be restored, allowing development of more natural forest, grassland and wetland habitats. The details of the scheme are still being finalised, taking in to account the results of studies and modelling, and implementation will be timed in the best interests of the local landowners.

Light or indepth?

In-depth

The in-depth description of the case study

cs-be-02-final_version.pdf

Location description

The measure is located along the floodplain of the Grote Nete, between the towns of Oosterlo and Nijlen, in northern Belgium.

NUTS Code

Prov. Antwerpen

RBD code

BESchelde_VL

Transboundary

Data provider

Heather Williams and Chris Binje, AMEC

Source(s)

Projectbrochure Vallei van de Grote Nete

Sigmaplan - Vallei van de Grote Nete

Project Nieuwsbrief - Vallei van de Grote Nete

Flankerend landbouwbeleid: Begeleiding van actieve landbouwers in Sigmagebieden.

NWRM(s) implemented in the case study

Wetland restoration and management

Floodplain restoration and management

Riverbed material renaturalization

Site information

Climate zone

cool temperate moist

Mean rainfall

800

Mean rainfall unit

mm/year

Average temperature

Type

Actual Test Site

Vegetation class

Wetland vegetation

Performance

Performance impact estimation method

Laboratory

Performance impact estimation information

The scheme has not yet been implemented, but its performance has been modelled.

Design & implementations

Application scale

River

Performance timescale

Immediate

Area subject to Land use change or Management/Practice change (ha)

850

Size

850

Size unit

Design capacity description

The NWRM increases the storage capacity in the river valley from 6.6 million m3 to 8.4 million m3.

Favourable preconditions

Only very limited development in the concerned area.
The areas to be included were originally the floodplain of the Grote Nete, so are well suited to restoration to their original purpose

Peak flow rate

Design contractual arrangement

Arrangement type	Responsibility	Role	Comments	Name

Design consultation activity

Activity stage	Name	Comments
Design phase	Meetings during planning phase	Meetings have been organized with all interested parties, including information provided through local city halls.
Implementation phase	Newsletters for residents	Regular newsletters have been made to inform interested parties of the progress of the project.
Implementation phase	Comprehensive website	On the website detailed animated videos can be found about what is going to happen including reasons for actions taken.
Implementation phase	Individual consultation with landowners	Individual consultation is held with each landowner to develop the best solutions

Design land use change

Land use change type
Pastures

Design authority

Authority type	Role	Name	Comments
Other	Implementation	Waterwegen en Zeekanaal NV	As steward of the waterways WenZ has overall responsibility for the project, from initiation of the measures and development of the plan to the actual implentation.
Other	Other	Agentschap voor Natuur en Bos	Involved in the development of new nature areas and wetlands.
Other	Other	Vlaamse Landmaatschappij (VLM)	Consulted in relation to changes to agricultural activities.
Other	Other	Departement Ruimtelijke Ordening, Woonbeleid en Onroerend Erfgoed (RWO)	Supports the spatial implementation of the project.

Lessons, risks, implications...

Key lessons

Integration of the project under the larger Sigmaplan enabled the project communication to go smoother and inter-agency communication was already established through the overarching plan.

Allowing long timescales is important and allows for the optimal outcome to be achieved, by allowing landowners greater flexibility.

Success factor(s)

Success factor type	Success factor role	Comments
Successful coordination between authorities	main factor
Conducted assessments (incl. economic)	main factor
Specific incentives for stakeholder involvement	main factor

Financing

Financing type	Comments
Sub-national funds	Funds provided by the Flemish government.

Barrier

Barrier type	Barrier role	Comments
Attitude of the public	main barrier	There are limits to the social support for large infrastructural changes with local communities, nearby residents, farmers etc. However the scale and government-backing of the Sigmaplan programme allows for extensive consultation to take place, as well as a compulsory purchase scheme if a voluntary agreement cannot be reached
Other	secondary barrier	Time consuming, due to the wide variety of studies (very multidisciplinary)

Driver

Driver type	Driver role	Comments
Past flooding events	main driver	Re-evaluation of flood risks (including expected climate change)
Other	secondary driver	Reinstatement of the estuary of the Scheldt as a self-sustaining ecosystem

Financing share

Financing share type	Share	Comments

Policy, general governance and design targets

Policy description

Main targeted problem is the high flood risk in the area.

Quantified objectives

The NWRM increases the storage capacity in the river valley from 6.6 million m3 to 8.4 million m3.

Part of wider plan

Policy target

Target purpose
Increase Water Storage
Improved Biodiversity

Policy pressure

Pressure directive	Relevant pressure

Policy area

Policy area type	Policy area focus	Name	Comments

Policy impact

Impact directive	Relevant impact

Policy wider plan

Wider plan type	Wider plan focus	Name	Comments
Catchment-based	Water	Sigmaplan	The Sigmaplan is a catchmentbased program for the river Scheldt. It was initially intended to mitigate the problems for tidal related floodings, but has since evolved to also include overall water safety measures.

Policy requirement directive

Requirement directive	Specification

Socio-economic

Direct benefits information

The following positive outcomes are expected:
- the social benefit of obtaining a self-maintaining estuary of the Scheldt and reducing flood risk;
- social benefit of creation of a natural area of a significant size (recreational value) ;
- indirect positive outcome to the economy through creation of recreation opportunities

Costs investment

25000000

Costs investment information

Estimate of costs at time of decision to proceed, at 2005 prices. Cost includes costs for infrustructural changes and land purchase.

Costs operation maintenance

The NWRM will reduce the recurring costs for dyke maintenance, but the cost for nature conservation will rise.

Costs disposal decommissioning information

No decommissioning is anticipated- the changes will be permanent

Compensations scheme information

The accompanying agricultural support measures are set under the framework of the Sigmaplan: - Support with identifying of exchange lands or company relocations - Extra time to transform the company by phasing the works - Bordercorrections to assure the liveabilityof companies by for example excluding lots with construction - Appealing retirement scheme
- Financial support for changing land-use from arable to pasture

Economic costs, income loss

2000

Information on Economic costs - income loss

The overall Sigmaplan foresees in a compensation of 2000 euros per ha for land users directly affected by the measures and compensation of 1000 euros per ha for land users not directly affected by the measure but who voluntarily make their lands available within the framework of the NWRM (for example as part of land exchange schemes with directly affected farmers). The land owners will get an allowance of atleast 20%. When the land owner and land user are the same, both compensations can be cumulated.

Ecosystem improved biodiversity

Information on Ecosystem improved biodiversity

Yes, new wetlands will be created on formerly agricultural land. Vegetation will change, with associated changes to soil and habitats for plants and animals

Ecosystem provisioning services

Information on Ecosystem provisioning services

The controlled storage areas are expected to have a flood frequency of 1 in 5 years, with agriculture use still being continued the rest of the time. At locations where nature will be developed, farmers will be given land elsewhere in the valley as a compensation measure.

Ecosystem impact climate regulation

No information available

Biophysical impacts

Information on retained water

The retention capacity of the floodplain will be 8.4 million m3

Runoff reduction

Information on increased water storage

The retention capacity of the floodplain was previously 6.6 million m3, so the implementation of the scheme represents an increase of 1.8 million m3

Runoff reduction unit

% Percent

Information on runoff reduction

Predicted by hydraulic modelling.

Water quality overall improvements

Neutral impact-no change in WQ status

Information on Water quality overall improvements

This has not been considered in detail in the study, although some effects on water quality may be expected through the creation of wetland habitat, in relation to sediment deposition and pollutant retention

Economic costs income loss unit

€/ha

Ecosystem erosion control impact unit

% reduction

Soil quality overall soil improvements

Neutral impact-no change in SQ status

Information on Soil quality overall soil improvements

The lands that will be made accessible to the water in the future have a higher probability of being influenced by pollutant deposition from the river. However, this has not been quantified.

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