Impact of drought on water quality in the Youssef Ben Tachafine dam (Souss-Massa region, Morocco)

The Massa catchment area has been experiencing an acute rainfall deficit for several years, which has had direct effects on the filling level of the Youssef Ben Tachafine dam. The objective of this work is to study the impact of the drought on the physicochemical quality and the biological balance of this aquatic ecosystem. A monitoring and bi-monthly analyses of the physicochemical and biological parameters (temperature, dissolved oxygen, pH, conductivity, transparency, manganese, iron, nitrate, ammonium, silica, phosphorus, and chlorophyll- a ) were carried out from January to December 2019. The considerable drop in the level of the reservoir has had a major impact on the degradation of the water quality of the lake and its trophic status. The analysis of the results showed that the trophic state of the Youssef Ben Tachafine dam is between mesotrophic and hypereutrophic.