This research was first investigated for an applied project: the development of a daily model for low flow forecasting. The studied area is located in the East of France and 60 basins are concerned. Our objective was to use our knowledge about low flow processes in the model. In a previous work, we have showed that the results of the model can be improved especially in forecast by using recession coefficients. These were calculated from an hydrological analysis and directly put in the model to calibrate base flow coming out from the groundwater storage of the model (Lang & al., EGU 2006). The main difficulties of this stage were related to the recession parameter variability, and the way of introducing it into the model.