Physical geography, geology, and water resource availability of the Souss-Massa River Basin

Abstract

This chapter presents synthesis results of physical geography, geology, and water resource availability of the Souss-Massa River Basin. The geomorphology and geology are very complex in detail. The actual valleys of Souss and Massa are due to erosion processes caused by floods. The Souss-Massa plain is a narrow fainting zone with recent sedimentary deposits, embedded between the High Atlas in the north and the Anti-Atlas in the south. The calibration of electrical soundings with deep boreholes allowed understanding of the geometry and the structure of the aquifer of Souss-Massa plain. The Souss-Massa area has a typical semiarid to arid climate with annual rainfall average ranging from 250 mm in the plain to 600 mm in the mountains. Plio-Quaternary shallow aquifer and Turonian deep aquifer constitute the major groundwater resource in the basin. The water resource availability of Souss-Massa River Basin is scarce; this situation is getting worse as a consequence of rapid population growth, expanding urbanization, increased economic and agriculture development, and natural forces (climate change). The renewable surface watermay vary a lot over the year or even between 1 year and another. It’s estimated at 667 million cubic meters. The construction of dams produces a number of economic and social benefits with a storage capacity reaching 639 million cubic meters. The groundwater availability is often being overexploited and polluted. On average groundwater abstraction exceeds recharge by an estimated 260 million cubic meters annually. This overpumping has led to a decrease in the water levels in a range of 0.5-2.5 m/year in the past 4 decades.