Evaluation of vulnerable zones to water pollution in the lower Soummam alluvial aquifer, Bejaia, Algeria

Abstract

Understanding the critical relationship between the Soummam River and its alluvial aquifer is crucial for the protection of this vital water resource. The approach is based on monitoring the spatial and temporal evolution of physico-chemical parameters and identifying their origin through correlation with the geology and piezometry of the alluvial aquifer; this will be achieved using differential gauging and hydrogeochemical tracing. This will provide valuable information for the management and protection of this precious water resource. The case study focuses on the alluvial aquifer of the lower Soummam Valley in Bejaia, Algeria, where a unique natural barrier upstream creates a close hydraulic relationship between the river and the aquifer. This allows for water exchange, which we investigated through two sampling campaigns (high and low water) at 32 water points (boreholes, wells and stations). By tracking the movement of special chemical tracers in both the Soummam River and the underlying alluvial aquifer, this study confirms a direct hydraulic connection between them. This means that water can flow from the river into the aquifer, highlighting the potential risk of water pollution. This has helped us to identify areas where pollution from the river could seep into the groundwater, threatening the drinking water supply. HIGHLIGHTS Determination of the existing exchanges between the river and the alluvial aquifer.; Monitoring of the spatial and temporal evolution of physico-chemical parameters.; Identification of the origin of the physico-chemical parameters.; Selection of differential gauging methods and hydrogeochemical tracing.; Identification of areas vulnerable to water pollution in the alluvial aquifer of the lower Soummam Valley.;

Keywords

• alluvial aquifer
• hydrogeochemical tracers
• hydrogeological threshold
• lower soummam
• infiltration-drainage