Geological and hydrological approach to surface Water Pollution in Inaouene Catchment Area

Ben Laghlagh Oumaima, Naoura Jamal, Hazyoun Zineb

The upper Inaouene waterched of approximately 1616 km2 is a principal source of drinking and irrigation water for the Taza region and is subjected to extreme hydrological conditions (floods and low-flows). This study focuses on the effect of such extrêmes on the contamination of surface waters and surface sediments by trace metals, with respect to geological and morphometric controls. The methodology implemented here combines morphometric studies, geologic interpretations, the spatial analysis using GIS, and the measurements of trace metal content at monitoring stations scarttered on the oued network. This framework provides a means of evaluating the associations between geological materials, hydrololgical regims, and levels of metal contamination. The findings suggest that the heterogeneity of the geology toghether with morphometry of the watershed exert strong controls on the spatial variations of trace-metal contamination of the oueds. Floods favor erosion, sediment exchange and downstream transfer of metal-rich particles. Low-flows facilitate the build-up and accumulation of trace metals in isolated zones. The composition of the underlying geology exerts a contol on the level of metal contamination. By combining the above methodology with the small number of sampling stations, this research offers quantitative insights into the short-term impact of hydrological extrêmes on trace metals in oueds. It helps to deepen the understanding of the processes for sustainable water management in semi-arid regions.