BW-06
Leaky dams & wet woodland
Haut-Lône headwaters,
France
47.2265° N, 0.1932° E
( Site file
146 leaky dams and new wet woodland in the Haut-Lône headwaters. Flood peaks now reach the bottom of the valley 3 h 40 min later.
The problem
The headwaters of the Lône drain a steep plateau. After heavy rain, the water reached the valley in a few hours and left the towns downstream very little time to prepare.
What we built
In 2024, with local crews, we built 146 leaky dams from felled timber across the small streams of the plateau, and planted wet woodland along their banks. Each dam lets normal flow pass underneath and holds back the flood pulse for a short time. Together, they slow the water without storing it behind one large structure.
Gauges above and below the dams compare each storm with the record. The flood peak now arrives 3 h 40 min later at the bottom of the headwaters. That is time the valley downstream did not have before.
Coordinates
47.2265° N, 0.1932° E
Commissioned
Structure
146 leaky dams and 38 ha of wet woodland
Scale
146 dams on 9 streams
Partner
Lône-Vire Water Agency
Homes behind the line
0
Sensors
12
Status
Monitoring
+3 h 40 min
delay to the flood peak downstream
( Readings
What this site measures,
and who checks it.
R-0451
Delay to the flood peak at Vire-sur-Lône
+3 h 40 min
Kerrow & Lisle Hydrology
Reported
