Modèles de fusion de la neige en un point et leur intégration dans les modèles hydrologiques de bassin versant

Abstract

This paper is a review of different works dealing with snow hydrology and particularly the modelling of snowmelt. The first model is a detailed one, based on present knowledge on snowmeltprocesses. This model was calibrated and tested on the data of two Iysimeter sites, located in the North French Alps, one in an open area and one in a forested area. The assymptions required are extensively discussed and have been sustained by further measurements. Using a 3 hours tune step, this model appears to be very satisfactory to simulate meltwater outflows and the thermal status of a snowpack at the end of the accumulation period and during the whole melt period. Then in order to fit the data usually available in mountaineous regions, the model structure was then slightly simplified, and the lacking data have been replaced by various estimations. The sensitivity of the model and the corresponding degradation of the results is shortly considered. It appears that a subroutine with a time step of 12 hours is sufficiently accurate for the majority of watershed models requirements. Such a subroutine which can easily be integrated in a complete watershed model, is finally presented. Finally, some remarks are presented concerning the usual snowmelt models using temperatures index and a meltfactor. The dependence of this factor on the types of weather situation (clear or overcast sky) has been specially pointed out and some conclusions are drawn for this particular type of models.