Dynamics of seasonal snowpack over the High Atlas
Title :
Dynamics of seasonal snowpack over the High Atlas
Snowpack melting in the High Atlas constitutes the major source of freshwater for the semi-arid agriculturalnplains of central Morocco. Snow runoff fills dams during spring and recharges groundwater, thus providing thennecessary water for irrigation and hydropower production. Despite its critical importance for the region, basicnquestions about the High Atlas snowpack remain largely unanswered. In particular, the spatial and temporalndistribution of snow water equivalent, as well as sublimation losses, potentially significant in this region, havenyet to be thoroughly investigated. The scarcity of ground data has been a major obstacle to investigating snownprocesses in the High Atlas. Here, we demonstrate the potential of remotely-sensed meteorological variables andndownscaled climate reanalysis data to gain important insights into snow water balance in a semi-arid region. Wenapply a distributed energy balance snow model based on SNOW17, constrained by topographic data, meteor-nological data from satellites and high-resolution dynamically-downscaled ERA-Interim data, to simulate snow-npack dynamics within the Oum-Er-Rbia watershed, at the heart of Morocco’s High Atlas. The simulations arencompared to MODIS snow cover maps and observed snow depth at one field station. Results show that the spatialnextent and temporal dynamics of snow cover at various elevation ranges are accurately captured. The snowpacknis essentially concentrated above 2500 m, extends over 500–6000 km 2 and holds 0.05–0.4 km 3 at its peak innearly February. Additionally, we find that losses by sublimation range from 0.06 to 0.14 km 3 for an average ofn0.09 km 3 a year, about 10% of all snowfall. Above 3000 m elevation, sublimation removes on average 20% of thensnowpack. Finally, we discuss the sensitivity of our results to uncertainties in the forcing meteorological data.nThis study reveals the essential components of the snow water balance in the High Atlas and paves the way fornbetter understanding of its sensitivity to climate change.nn