Hydrological impact of forest-fire from paired-catchment and rainfall-runoff modelling perspectives

This study deals with the Rimbaud catchment, a sub-catchment within the Real Collobrier hydrological observatory in southeastern France, managed by Irstea since 1966. This observatory suffered a wildfire in 1990. Because of the dense network of streamgauges and raingauges available, this site provides a unique opportunity to test and compare two types of analysis, one based on paired catchments and the other a rainfall-runoff model, used to assess the hydrological impact of forest fire. In the present case, more than 20years of pre-fire and post-fire data are available. We compare the ability of the two approaches to detect gradual changes at a daily time step. This case study illustrates how natural climatic variability (here a long drought which preceded the wildfire) can make the identification of hydrological changes extremely difficult.