STOCKAGE A LA SOURCE - WWF Belgium

Recensement des actions de stockage de l’eau en amont des bassins hydrographiques
The WWF Fresh Water Unit then embarked in a water retention project called
“Ardennes-Meuse”. The aim of this project is to reduce the Meuse floods downstream
during strong rainfalls and to increase the water supplies during dryer periods, using
ecological and sustainable solutions, by an enhancement of water retention upstream.
The different aforesaid partners have identified key zones in areas that once converted
and re-dynamized, will be able to act again as natural sponges thus fulfilling their role
in water storage. This training course fits into this “Ardennes-Meuse” project, forming
a part of a wider project, “Storage at source in Rhine and Meuse hydrographical
basins”, which fits into the WWF international “One Europe More Nature” project.
The latter identifies regional opportunities to show that economy and ecology can work
together for an improvement of our life style, along with the protection of future
generations and in keeping with nature.
We distinguish two main types of approaches bound to decrease the fresh water linked
issues. The first one is to act downstream from the rivers; the second one is described
by the storage at source concept that aims at acting upstream from those rivers.
3. Downstream sustainable solutions
During this training course, many projects and experiments targeting the fitting-outs
downstream from the rivers and in alluvial plains have been reviewed. Those projects
that are distributed across Europe typically aim at the re-value and recovery of the
original state of basins and alluvial plains. New possibilities of longer lasting water
retention and floodwaters flow slowdown, by allowing more frequent inundations of
these alluvial plains, are investigated by those projects.
Some of them, located downstream, tend to free the rivers and streams. After fittingouts,
changes of rivers directions or even sometimes without any human intervention,
they evolve in a more natural morphology, similar to the one they had before. Thus,
during extreme events, the entire alluvial plain is inundated and water stocked for a
longer time. This kind of fitting-out is known as floodplains restoration or rivers
recovery. Flood plain obstacles elimination, flood canals network lay-out, flood plain
widening at a lower level, controlled inundation of particular uninhabited areas of
alluvial plains, allow the water floods progression to slowdown, thus giving the water
floods the time to decrease.
4. Upstream sustainable solutions
In the middle mountains massifs and heads of catchment areas upstream, where a lot of
rivers of our countries originate, space available for water retention is not lacking.
Indeed, a part of the precipitation falling over the middle mountains massifs is retained
for a few days. Possibilities of water retention and storage are thus feasible there. This
is the storage at source concept.
In those areas close to the sources, water flow retention can be promoted by the
elimination of artificial accelerated evacuation facilities (dykes, evacuation canals,
river bed deepening…), humid areas and conifer forests drainage, conifer woods
replacement by leafy woods, and by a part of intensive agriculture and pastures
reduction.
To enhance the soil adsorption capacity, there is thus often a need to modify the soil
usage itself. Indeed, vegetation laying in the middle mountain massifs has almost
disappeared and is replaced by fields and pastures. High peat bogs that covered about
10% of those massifs surface have been subjected to the same destiny. They have been
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