Testing multiple structures of a lumped hydrogeological model to simulate karst spring discharge in France and provide seasonal forecasts in the Aqui-FR platform

Karst springs represent an important source of drinking water. Karst aquifers are highly complex and heterogeneous hydrogeological systems made of poorly known conduit networks which makes springs discharge difficult to forecast. Lumped hydrological models can only satisfactorily model karst systems if they consider both diffuse and localised infiltration, and matrix and conduit flow pathways. The French Geological Survey developed RAMEAU (River and Aquifer Model of the frEnch geological sUrvey), a flexible lumped hydrogeological model conceptually encompassing these processes in its model structure. The objective of this study is to demonstrate the versatility of the model to simulate discharge in a variety of karstic systems in France. This study evaluates the performance of the different model structures to simulate the discharge of a large sample of French springs. The models are calibrated on decades long time series of observed spring discharge, and the best model structure is selected independently for each spring. These models are then integrated in the Aqui-FR platform, a multi-model platform that provides hydrogeological seasonal forecasts over continental France.