Long-term analysis of snow-covered area in the Moroccan High-Atlas through remote sensing

The High-Atlas mountainous region in Morocco is a true water tower for the neighbouring arid plains, where the water resources are intensively and increasingly subjected to exploitation for agriculture and tourism. In order to manage this resource sustainably, it is necessary to describe accurately all the processes that contribute to the hydrological cycle of the area, and, in particular, to know the respective contributions of liquid and solid precipitations to runoff. In this context, a seven-year time series of SPOT-VEGETATION images is used for mapping snow-covered areas. The spatial and temporal variations of the snow cover are analyzed for the entire High-Atlas region as well as by altitudinal zones. The spatial distribution of snow-covered areas appears logically controlled by elevation, and its temporal fluctuations can be clearly used to identify dry and wet seasons. In addition, a possible control of snowfalls by the Northern Atlantic climate variability, and, in particular, the North Atlantic Oscillation, is highlighted. Finally, this study shows how satellite remote sensing can be useful for the long-term observation of the intra- and inter-annual variability of snowpacks in rather inaccessible regions where the network of meteorological stations is deficient.