A method for assessing the influence of rainfall spatial variability on hydrograph modeling. First case study in the Cevennes Region, southern France

Emmanuel et al. (2015) proposed rainfall variability indexes intended to summarize the influence of spatial rainfall organization on hydrograph features at the catchment outlet. The present article shows how the proposed indexes may be used in a real-world case study to analyze the influence of spatial rainfall organization on hydrograph modeling. The selected case study is located in the Cevennes Region of southeastern France. The proposed methodology is as follows: the tested flow events are split into two subsets according to the values of their rainfall variability indexes; then, a comparison is drawn between modeled and measured hydrographs separately for each subset. The results obtained suggest that, on average, modeling results based on high-resolution rainfall data are improved for the subset whose rainfall variability influence is expected to be significant according to index values. Though limited to a relatively small number of hydrographs, this case study can be viewed as a first confirmation that the proposed method, based on the rainfall variability indexes of Emmanuel et al. (2015), is pertinent to investigating the influence of spatial rainfall variability on hydrograph modeling results.