Innovative use of soil bioengineering for erosion and sedimentation control in the Durance catchment

Abstract

Soil erosion on marly terrains is a frequent problem in the mountain and Mediterranean areas in the Durance catchment in the French Southern Alps. One of the consequences of this erosion is high yields of fine sediment at the exit of catchments, which can cause economic, social and ecological damages downstream. To avoid these sediment transports, an innovative use of bioengineering techniques can be considered by letting erosion occur on slopes while retaining the eroded materials before they reach the catchment exit, therefore obtaining low sediment yields with as few interventions as possible. This can be carried out with the use of bioengineering structures within small gullies, where vegetation obstacles can play a very significant role in sustainable trapping and retention of fine sediment in gully floors. The application of such 'low-cost' ecological action requires establishing a specific strategy for the interventions. To do this, research has been carried out since 1998, aimed at better understanding the role of bioengineering structures and vegetation in controlling erosion and sedimentation in marly torrential catchments in a mountainous and Mediterranean climate. Results were then used to propose rules, simulations and an action plan for such a control at the scale of the Durance catchment in France.