National Id
Site name
Grote Nete between Oosterlo and Nijlen
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?
The in-depth description of the case study
Location description
The measure is located along the floodplain of the Grote Nete, between the towns of Oosterlo and Nijlen, in northern Belgium.
Prov. Antwerpen
RBD code
Data provider
Heather Williams and Chris Binje, AMEC
Climate zone
cool temperate moist
Mean rainfall
Mean rainfall unit
Average temperature
Actual Test Site
Vegetation class
Wetland vegetation
Performance impact estimation method
Performance impact estimation information
The scheme has not yet been implemented, but its performance has been modelled.
Application scale
Performance timescale
Area subject to Land use change or Management/Practice change (ha)
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 Key issues 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
Design authority
Authority type Role Responsibility Name Comments
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.
Agentschap voor Natuur en Bos
Involved in the development of new nature areas and wetlands.
Vlaamse Landmaatschappij (VLM)
Consulted in relation to changes to agricultural activities.
Departement Ruimtelijke Ordening, Woonbeleid en Onroerend Erfgoed (RWO)
Supports the spatial implementation of the project.
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

As this project is part of the Sigmaplan, overarching consulting pre-existed prior to the project within the sectoral consultation bodies (agriculture, nature, government, ...). This enabled to get all local stakeholders involved as well in an early phase to successfully coordinate any issues during the design phase.

Conducted assessments (incl. economic)
main factor

Although time consuming, the preceding studywork (reports regarding effects on agriculture and nature development, details of ground- and surface waters, ...) lead to a complete development plan which enhanced coordination greatly.

Specific incentives for stakeholder involvement
main factor

The Sigmaplan has a comprehensive approach to consulting with stakeholders and finding solutions to allow the measures to progress on their land

Financing type Comments
Sub-national funds
Funds provided by the Flemish government.
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
secondary barrier
Time consuming, due to the wide variety of studies (very multidisciplinary)
Driver type Driver role Comments
Past flooding events
main driver
Re-evaluation of flood risks (including expected climate change)
secondary driver
Reinstatement of the estuary of the Scheldt as a self-sustaining ecosystem
Financing share
Financing share type Share Comments
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
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
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
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
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
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
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.