Journal Article

Characterization of mechanisms and processes of groundwater salinization in irrigated coastal area using statistics, GIS, and hydrogeochemical investigations

Slama, Fairouz, Bouhlila, Rachida, Elango, L, Ouslati, Naceur, Bouzourra, Hazar

2015

Overview

Coastal aquifers are at threat of salinization in most parts of the world. This study was carried out in coastal shallow aquifers of Aousja-Ghar El Melh and Kalâat el Andalous, northeastern of Tunisia with an objective to identify sources and processes of groundwater salinization. Groundwater samples were collected from 42 shallow dug wells during July and September 2007. Chemical parameters such as Na⁺, Ca²⁺, Mg²⁺, K⁺, Cl⁻, SO₄²⁻, HCO₃⁻, NO₃⁻, Br⁻, and F⁻were analyzed. The combination of hydrogeochemical, statistical, and GIS approaches was used to understand and to identify the main sources of salinization and contamination of these shallow coastal aquifers as follows: (i) water-rock interaction, (ii) evapotranspiration, (iii) saltwater is started to intrude before 1972 and it is still intruding continuously, (iv) irrigation return flow, (v) sea aerosol spray, and finally, (vi) agricultural fertilizers. During 2005/2006, the overexploitation of the renewable water resources of aquifers caused saline water intrusion. In 2007, the freshening of a brackish-saline groundwater occurred under natural recharge conditions by Ca-HCO₃meteoric freshwater. The cationic exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. The sulfate reduction process and the neo-formation of clays minerals characterize the hypersaline coastal Sebkha environments. Evaporation tends to increase the concentrations of solutes in groundwater from the recharge areas to the discharge areas and leads to precipitate carbonate and sulfate minerals.

• Publisher: Springer-Verlag,Springer Berlin Heidelberg,Springer Nature B.V
• Subject: aerosols / Agriculture / Aquatic Pollution / Aquifers / Atmospheric Protection/Air Quality Control/Air Pollution / bicarbonates / bromides / Bromides - analysis / calcium / Carbonates - analysis / chlorides / Chlorides - analysis / Coastal / Coastal aquifers / Coastal zone / Coasts / Discharge / drainage water / Dug wells / Earth and Environmental Science / Ecotoxicology / Environment / Environmental Chemistry / Environmental Health / Environmental Monitoring - statistics & numerical data / Evaporation / Evapotranspiration / fertilizers / Fluorides - analysis / Fresh Water - analysis / freshwater / Geographic Information Systems / Groundwater / Groundwater - analysis / Groundwater irrigation / Groundwater recharge / Hydraulic gradient / Irrigation / Magnesium / Metals - analysis / Minerals / Natural recharge / Nitrates / Nitrates - analysis / Overexploitation / Pollution sources / potassium / Principal components analysis / Renewable resources / Research Article / Return flow / Saline water / Saline water intrusion / Saline-freshwater interfaces / Salinity / Salinization / sodium / Solutes / Sprays / Statistical analysis / statistics / Stratigraphy / sulfate minerals / Sulfate reduction / Sulfates / Sulfates - analysis / Surface water / Tunisia / Waste Water Technology / Water analysis / Water Management / Water Pollutants, Chemical - analysis / Water Pollution Control / Water resources / Water sampling / wells