Présentations Colloques

Oral Presentation
5.01
Session 5.01: Groundwater resources in a world facing climate change
Colmet Daage Antoine
Climate change impacts on flash flood in Mediterranean mesoscale catchments
The Lez catchment is a meso-scale karstic basin covering 114kmC in Southern France. This Mediterranean river is subject to extremes floods events linked to intense convective precipitation along with a karstic aquifer contribution. The Mediterranean region is known to be one of the most affected areas by global warming, and hydrological cycle changes are likely to be expected. **The aim of this study is to assess local climate change impacts on flash flood events using a so-called “futurization” method, in which a transfer function is built by comparing the distribution quantiles for both current and future climate precipitation. A number of historical flash flood events within the Lez catchment, previously selected using rain gauges’ data, are “futurized” using the precipitation outputs from Regional Climate Models. Once the future counterpart precipitation event is determined, it is used as input to Lez catchment hydrological models. The results are used to quantify the past future differences in terms of flood peak amplitude, discharge volumes as well as frequency. **ATHYS is an event-based, distributed, parsimonious hydrological model. It has been calibrated and adapted to the Lez basin by Coustau et al. (2012) for the 1994-2008 period. The parameters, once calibrated, remain fixed for all events, except for the initial soil moisture which control the infiltration capacity.**Currently, past and future flash floods events are simulated using the same infiltration capacity parameter, which is determined through a piezometrical level measured the morning before the event. Model sensibility tests have been done on this parameter by using random values around the past level. The effect of this parameter on the runoff production function is stronger than the precipitation change. Therefore, its future optimization is mandatory to only extract the climate change effects on flash floods.**
France