Managed Aquifer Recharge in a Semi-arid Basin: A Case Study from the Souss Aquifer, Morocco

In the Souss River Basin (SRB), Morocco, with a semi-arid climate, the long-term droughts combined with groundwater overexploitation, cause serious concern about groundwater depletion and quality. Limitations in water supplies and increasing demand for water have caused greater interest in artificial groundwater recharge as a means of underground storage of seasonally variable surface runoff. The managed aquifer rechargeManaged aquifer recharge (MAR) program was one of the main programs to ensure the sustainability of water resources, especially during drought periods. In the SRB, the MAR consists of direct recharge techniques through retention sills in the Souss River and its tributaries, in addition to rainwater harvestingRainwater harvesting. For the first time, MAR was carried out by the Hydraulic Agency of Souss-Massa Basin, from the Aoulouz (in 1990) and Imi El Kheng (in 1993) dams, by regulating water resources through scheduled releases with an average volume of 83.7 Mm3/year since its implementation. The maximum infiltrationInfiltration is highlighted between the middle and the upstream part of the basin where the hydraulic conductivity is very high. The recharge occurs mainly along the bed of the Souss River and its streams which is confirmed by the water level variability in some piezometers. The isotopic tracers are used to investigate the signal of natural recharge. The results show that the groundwater had experienced evaporation through the unsaturated zone before infiltrationInfiltration and that the recharge altitude ranged from 400 to 2350 according to a gradient of −0.18%/100 m.a.s.l. In addition, rainwater harvestingRainwater harvesting in hillside lakes and small reservoirs have also an important role in relieving the pressure on water resources, especially in the isolated areas in the upstream part of Souss. AquiferAquifers enhanced recharge remains still insufficient to meet the water needs, there for other strategies and alternative solutions have been suggested in this study.