Characterization of hydrodynamic and pollutant removal processes inside swales - a pilot study

Swales are stormwater source control infrastructures that manage runoff in two dimensions. Generally, a first part of the volume discharged in a swale is conveyed as surface flow and the other is infiltrated underground. A swale traditionally aims at reducing and slowing runoff flows but swales can also decrease the load of sediment and other pollutants in urban runoff by promoting infiltration and sediment deposition. The literature describes some design swales criteria but their effects on the quantity, the repartition and the speciation of pollutants in the soil remain unclear. This study focuses on hydraulic and pollutant removal performances of swales and aims to define and characterize the physical and physicochemical processes governing water and pollutant flows in these unsaturated soil-water reactors. From an operative point of view, this work takes part in the Matriochkas project and consists in determining the environmental performances of swales. After a state of the art focusing on the swale pollution retention performance, the paper details some experimental specifications to build a pilot experiment to characterize hydrodynamics and pollutant removal within swales. First tests are expected to be realized before June 2016.