Seawater intrusion and associated processes: Case of the Korba aquifer (Cap-Bon, Tunisia)

Abstract

It has been established that intensive agricultural activities, usually, increase the risk of groundwater quality degradation through high groundwater pumping rates. In fact, the uncontrolled groundwater extraction causes a modification of natural flow systems and induces seawater intrusion from the coast and causes the groundwater quality deterioration. The Korba aquifer is located in the North-East of Tunisia, where a semi-arid Mediterranean climate prevails. The dry season is pronounced and this aggravates the situation, given that the highest water demand usually coincides with the drought period (dry weather conditions). The principal aim of this study is to characterize the hydrochemistry of this coastal aquifer, identifying the main processes that occur in the system, and to determine the extent of marine intrusion in the aquifer. In order to achieve this aim, geophysical and chemical parameters were measured, such as vertical electrical soundings (VES), electrical conductivity, pH, temperature, anions and cations concentrations. The analytical results obtained in the hydrochemistry study were interpreted using ion correlations with chloride and SO 4 2-/Cl À and Mg 2+ /Ca 2+ ratios, in conjunction with calculations of the ionic deviations and the saturation indexes. Saturation indexes are calculated with the PHREEQC 2.8 software used for mineral saturation modelling of the aquifer seawater-freshwater mixture. The high groundwater salinity anomaly observed in Diar El Hajjej, Garaet Sassi and Takelsa-Korba zones was explained by the presence of seawater intrusion in these areas. This hypothesis is based on high chloride concentrations, the inverse cation exchange reactions, and the lower piezometric level compared to sea level.

Combining boron isotopes and carbamazepine to trace sewage in salinized groundwater: A case study in Cap Bon, Tunisia

“…It showed almost no enrichment in magnesium and depletion in sodium and potassium. Na and K depletion along with Ca and Sr enrichment are in agreement with the cation exchange process (detailed in the Supporting Information) which were previously described (Ben Hamouda et al, 2011;Cary et al, 2012 a,b;Kouzana et al, 2009;Lerouge et al, 2010;).…”

Hydrogeochemistry and groundwater salinization in an ephemeral coastal flood plain: Cap Bon, Tunisia

“…Several studies focused mainly on understanding the flow and hydrological budget of the regional groundwater flow system (Rouatbi 1968, Ennabli 1980, Rekaya 1989, Khlaifi 1998, Paniconi et al 2001, Chattouti 2006, Kerrou 2008, Zghibi 2011. Some others have dealt with characterizing the qualitative degradation of the aquifer caused by seawater intrusion (Kouzana et al 2009, Ben Hammouda et al 2011). All the above-mentioned authors focused exclusively on regional groundwater flow; there is no previous work that has studied small-scale groundwater flow and contamination.…”

Regional variations in the chemical and helium–carbon isotope composition of geothermal fluids across Tunisia

“…We note however that a few cold water samples, collected near the coast (e.g. sample 26), depart from the bicarbonate-type waters, and trend towards the compositional field of chloride-sulfate alkaline waters; this, when looked in tandem with increasing TDS values, supports some extent of seawater contribution to coastal shallow aquifers, as already reported in Tunisia for instance in the case of the Korba aquifer, Cap Bon (Kouzana et al, 2009(Kouzana et al, , 2010 or the Sfax superficial aquifer (Trabelsi et al, 2005(Trabelsi et al, , 2007.…”