Speaker
Description
In the context of climate change, marked by rising temperatures and decreasing precipitation across several regions of Morocco, surface water resources—particularly reservoir impoundments—are facing increasing pressure. The Hassar dam reservoir, located northeast of Casablanca, is no exception and represents a specific example of these dynamics. This water body is mainly supplied by treated wastewater from the Mediouna treatment plant, in addition to increasingly limited natural inflows due to prolonged drought. It plays an important ecological and socio-economic role in the region. This study aims to assess the effects of drought on the physicochemical and biological quality of the reservoir’s waters over 12 months, from March 2024 to February 2025. The results reveal an alarming situation: the waters are eutrophic to hypertrophic (chlorophyll-a = 51.81–86.06 µg/L), with high biological oxygen demand (BOD₅ = 17.6–32.9 mg O₂/L) and elevated nutrient concentrations (NO₃⁻ = 0.48–0.92 mg/L; PO₄³⁻ = 0.21–0.33 mg/L). Furthermore, mineralization parameters indicate high values, with electrical conductivity (EC) ranging from 13.86 to 19.58 mS/cm, and sulfate (SO₄²⁻) concentrations between 254.85 and 480.02 mg/L, reflecting a significant load of dissolved salts. This water quality deteriorates further during the spring-summer period, which coincides with rising temperatures and reduced rainfall. The combined analysis of water quality data and local climatic indicators during the study period highlights the direct impact of climate change. According to recent reports from the General Directorate of Meteorology, Morocco recorded in 2024 an average rainfall deficit of 24.8% compared to the 1991–2020 reference period, reaching up to 53% in certain regions when compared to the average over the last 30 years (1995–2024). Meanwhile, the year 2024 was characterized by a national average temperature anomaly of +1.49°C, with peaks reaching +3.09°C in November. These extreme climatic conditions have led to a marked reduction in pollutant dilution by natural inflows, an increased concentration of nutrients and dissolved salts, and intensified evaporation processes—ultimately accelerating eutrophication and mineralization within the reservoir. This study highlights the pressing need to adopt adaptive and integrated water resource management strategies to mitigate the impacts of climate change in Morocco. Such approaches should account for both climatic and anthropogenic dynamics to ensure the ecological resilience and sustainable use of artificial wetland systems.
Keywords: Climate change, water quality, eutrophication, dam impoundment, Casablanca, water stress
