Hydrogeochemical and qualitative assessment of groundwater in a southern Mediterranean region: an example of the Aïn Témouchent area (northwestern Algeria)

Abstract

The present research aims to assess the hydrogeochemical processes, the suitability of groundwater for human consumption, and the influence degree of seawater intrusion of the coastal aquifers of the Aïn Témouchent region (northwestern Algeria). In this context, 29 groundwater samples were taken during April–May 2018 and analyzed for 11 physicochemical parameters. Piper and Chadha's diagrams allowed the identification of Na–Cl dominant hydrogeochemical facies and Ca (Mg)–Cl type facies, indicating the influence of salt water. Simpson's Index results highlighted that groundwater was slightly contaminated by saltwater. Obtained values of the seawater mixing index (SMI) and Cl−/(HCO3−), Na+/Cl− and Ca2+/Mg2+ ratios indicated the majority of the sampling sites are affected by seawater intrusion. The integration of the water quality index (WQI) spatial variation through the geographic information system (GIS) indicated that in the Southern part of the study region, and 55.2% of water samples are suitable as drinking water. Adversely, for the northern part, where groundwater is influenced by seawater intrusion, water sampling points fall into bad and very bad categories. The results of the study show that hydrogeochemical processes are responsible for the salinity of groundwater in the study area, in addition to marine intrusion. HIGHLIGHTS It investigates the quality of groundwater for domestic use.; The study focuses on the influence of seawater and Oran sebkha on groundwater hydrogeochemistry.; Dominant ions in groundwater are in sequence: Na+ > Mg2+ > Ca2+ > K+ and Cl– > HCO3– > SO42– > NO3–.; Coastal wells near Oran Sebkha wells are contaminated by saltwater intrusion.; Water facies prevailed with Na+–Cl– (52%), and Ca–Mg–Cl (38%).;

Keywords

• coastal aquifers
• drinking water
• ion exchange
• nw algeria
• seawater intrusion
• water quality