caracterisation et fonctionnement geochimique des eaux de sebkha el mahmel. Khenchela - Algerie
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Date
2022
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Abbes Laghrour University- Khenchela
Abstract
The objective of this study is to respond to the salinization of water by identifying the processes
of mineralization and discriminating against the mechanisms involved.
With an area of 343.55 Km2, the basin of Essbikhat-El-Mahmel extends from North-West to
the South-East of the Eastern piedmont of the Aurès massif (North-East Algeria), it is occupied
in its eastern part by a Sebkha (the sebkha of El-Mahmel), which is a natural outlet for surface
and groundwater. In this region, groundwater is the first material and is under great pressure, it
is the only resource available to satisfy the needs of the population in terms of drinking water
than for irrigation and the various activities of which water is the raw material.
It is a depression filled with a Mio-Plio-Quaternary, consisting of clay, sand, and gravel, which
surmounts Maastrichtian limestones and the whole, is deposited on Cenomanian marls.
Potential aquifers are superficially based on alluvium and a deep aquifer consisting of cracked
limestones from upper Maastrichtian. The climate is semi-arid with long and recurrent periods
of drought, combined with strong evaporation marked by a water deficit.
The hydrochemical study showed that the salinity of the water gradually evolves in the direction
of water flow to reach conductivity values of 4560 μS/cm. The chemical facies of the water is
defined by calcium bicarbonate in limestone outcrops passing to calcium sulfated water by the
dissolution of gypsum and finally calcium chloride at the borders of the Sabkha. The
geochemical signature of groundwater is controlled by dissolution processes and mineral
precipitation due to water-checkmark interaction, cationic exchanges, anthropogenic activity,
irrigation water return, and climate aridity.
The results of the Drinking Water Quality Index (IWQ) showed that 67.57% of the samples are
of good quality the rest varies between poor and very poor quality.
The assessment of the chemical quality of groundwater for irrigation by calculating the
Irrigation Water Quality Index (IWQI) reveals that this groundwater is classified as "low
restriction" to "very high restriction".