Hydrochemical, Microbial and Ecological Deterioration of the Sebou River: A Full-Spectrum Review

This review synthesizes 37 scientific studies and technical reports on water quality degradation in the Sebou River over three decades. The results reveal persistent and spatially contrasted pollution, with particularly severe degradation in the middle Sebou downstream of Fez. River waters exhibit extreme organic and nutrient loads, chronic hypoxia, elevated heavy metal contamination, and exceptionally high microbial levels, frequently exceeding international guideline values. These pressures have led to a collapse in biodiversity, characterized by the loss of sensitive species and the dominance of pollution- tolerant taxa. At the same time, sediments act as long-term reservoirs of pollutants. Eutrophication emerges as a central process linking organic pollution, microbial contamination, metal mobilization, and biogeochemical instability. Despite localized improvements, ecological recovery remains limited, highlighting the need for integrated basin-scale management to achieve sustainable restoration of the Sebou River.