Abstract
Floods are among the most damaging natural hazard in the world. In south of France, most of theflood events are called ‘flash flood’, because of the fast response of rivers to rainfall. This is mainlydue to the particular climatic setup of this area which is responsible for intense storm, with largeamount of rainfall within a few hours on limited areas. In this project, we study these flood events inbasins connected with karst aquifers. These ‘karst flash floods’ are specific because karst terrains willreact differently than ‘classical’ basins. Depending on the initial water table level, the karst may reduceor amplify the flood in the river. This specific behaviour of karst basins is a key issue for the Frenchnational services of flood prediction which finance the project. Most of flood modelling frameworks aredesigned for surface processes only and do not allow the explicit representation of the karstprocesses. This explains the poor performances obtained by these models when applied on karstbasins. On the opposite, hydrogeological models do not allow an efficie nt representation of surfaceprocesses. The aim of the project is to analyse karst flash flood in order to understand theseprocesses and their influence on surface flood. This project concerns eight basins in two departments(Aude and Herault) of southern France, linked with different karst aquifer (binary and unary karsts,from Cambrian to Cretaceous ages). The first step consisted in gathering a large database on thesebasins, at a specific spatial (surface basin) and temporal (flood duration) scale, and to pre-processthese data. This poster presents our database, the uncertainties associated with each data, and how itwill be useful for analyses and modelling. This database contains various kinds of data (rainfall,piezometric level, soil moisture, discharge, geochemical analyses of water during flood, inhabitanttestimonies, flood marks and other qualitative data), but our goal is to integrate more data from postcrisis enquiries in our database.