A pragmatic simulation of karst spring discharge with semi- distributed models. Advantages and limits for assessing the effect of climate change

A hydrological semi-distributed model for simulating karst springs discharge is presented and applied to the Flims case study (Graubünden) and the Milandrine underground river (Jura). This model used for flood prediction and management in river basins has been adapted to karst flow and springs. The model takes into account snowmelt, glacier melt, soil infiltration, evapotranspiration as well as flood routing in surface rivers, sinkholes, and fast and slow flows in underground reservoirs. The Flims karst system is composed of three springs at three different levels: Lag Tiert, Tunnel spring and Pulté spring. In 2002, flows in the system were disturbed by the drilling of a highway tunnel. After a long work of development the model is now able to simulate the discharge rate of these three springs. It allows us to evaluate the effect of the tunnel drilling and the potential effect of the climate change. The first results for the Milandrine River are not as good as the ones of Flims because the simulation of the recharge through the soil and of complex storage processes in the cave conduits is not very easy with the selected approach.