Natural Flood Defences

Rhine/Meuse

Wouter Helmer

Ark Foundation

Ark Foundationnature and landscape development• More room for natural processes

Ark Foundationmain principles

• More room for natural processes• (Economic) Partnerships

Ark Foundationmain principles

• More room for natural processes• (Economic) Partnerships• Local commitment

Ark Foundationworking method

Regional vision Local examples

Upstream: Ambleve (Ardennes)‘Mountains of Water’ Geulle (Limburg-NL)

Downstream Millingerwaard‘Living Rivers’ (Gelderse Poort)

Mountains of Water

• Retention in brooks (Ambleve, Ourthe, Geulle, Worm, Ober-Main)

• Waterretention in lower mountains (Ardennes,

Eiffel, Schwarzwald)

Mountains of Water

• Waterretention in lower mountains (Ardennes,

Eiffel, Schwarzwald)

Mountains of Water

• Waterretention in lower mountains (Ardennes, Eiffel, Schwarzwald)

Meuse: reduction of discharge by restoration of the natural sponges in brooklets Ardennes :

3000-3500 m3/s Borgharen: ca.6 % reduction!

Mountains of Water

- Remove campshedding- Let falling trees deregulate stream- Clay-layer from centuries of unnatural

sedimentation will be removed by the brook

Retention in brooks (Ambleve, Ourthe, Geulle, Worm, Ober-Main)

Mountains of water

Mountains of Water

• Retention in brooks (Ambleve, Ourthe, Geulle, Worm, Ober-Main)

1924 1975 1989

Mountains of Water

Retention in brooks (Ambleve, Ourthe, Geulle, Worm, Ober-Main)

Meuse: reduction of discharge by restoration of the natural floodplains of the larger brooks:

3000-3500 m3/s Borgharen: ca. 5 % reduction!

Living Rivers

• Clay excavation

• Sidechannels• Herbivory

• Cyclic rejuvenation

Living Rivers

• Clay-excavation

Living Rivers

Living Rivers

• 50.000 new houses = ca.150 ha new nature

Living Rivers

• Sidechannels

Living rivers

• 220 km new side channels• Compensation for natural vegetation and new

riverdunes

Living Rivers

• Herbivory

Wild horses and cattleanimal/2-4 ha yearrounddelay of forest development

Beaver4000 kg/year/beaverlocal clearcutting of riverine forestsfacilitates grazing

Living Rivers

Living Rivers

Living Rivers

16.000 m3/s: solutions within Riverforelands

18.000 m3/s: Old Rhine/Linge-floodplain

Living Rivers