Abstract

In the Laâyoune Sakia El Hamra region of Morocco, characterized by scarcity, fragility, and uneven distribution of water resources, acute water stress is prevalent due to overexploitation, climate change, and the escalating degradation of water quality from human activities. The Sakia El Hamra River, a vital watercourse, is subjected to continuous pollution from domestic waste and untreated wastewater from Laâyoune city, impacting a section designated as a Ramsar site. This study aims to enhance understanding of these impacts within the region. A series of physicochemical parameters were monitored spatiotemporally at multiple points along the river, both upstream and downstream of the Sakia El Hamra dam. The findings indicate that while the reservoir water maintains acceptable quality, influenced by evaporation, the salinity levels do rise. Conversely, the downstream water quality exhibits excessive mineral concentrations, far surpassing acceptable standards, as evidenced by elevated electrical conductivity. Furthermore, significant pollution levels are confirmed by high measurements of biochemical oxygen demand, chemical oxygen demand, total phosphorus, ammoniacal nitrogen, and other contaminants.  The mapping of water quality indicators in the Oued Sakia El Hamra River, was achieved using a Geographical Information System (GIS) based on the Water Quality Information System and spatial analysis with Inverse Distance Weighted (IDW) interpolation. The analysis reveals that the water quality downstream poses a substantial risk to the Foum El Oued aquifer and the local aquatic ecosystem, especially in zones affected by wastewater discharge and spring runoff. Mapping water quality will help to monitor and enforce standards and regulations to manage and control pollution.