Hydroclimatic Variability of Aguelmam Sidi Ali (Middle Atlas Central, Morocco) over the Past Four Decades

The Aguelmam Sidi Ali is the largest natural lake in the Middle Atlas, both in size and depth. During the last four decades, the lake has experienced very marked fluctuations in its water level, and its general trend is tending to shrink. It is the manifestation of increased climatic drought. In this context and with the aim of studying the hydroclimatic variability, a bathymetric record was made during 2017 which seems to be an arid year, in order to make comparisons with those of the hydrological year 1975/1976 when the lake reached its maximum level. We also correlated between the lake level and the climatic parameters influencing its water balance. The data analyzed reflects changes in lake level and reflects the weight of climate variability in the area and its impact on the lake's water supply. The results obtained confirm a continuous decrease in the lake's limnimmetry. The lake's extent is considerably reduced, its maximum depth was of the order of 40 m instead of 43.5 m in 1975, and the water balance (P- PET1) records a deficit of 242 mm/year throughout the observation period (1975/76 - /2016/17).