TITLE:
Using GIS and Geostatistical Techniques for Mapping Piezometry and Groundwater Quality of the Albian Aquifer of the M’zab Region, Algerian Sahara
AUTHORS:
Mansour Achour, Moulay Idriss Hassani, Hadjira Benhedid, Abla Hadj Brahim
KEYWORDS:
M’zab, Albian, NWSAS, AAMR, Groundwater, Geostatistical
JOURNAL NAME:
International Journal of Geosciences,
Vol.12 No.3,
March
25,
2021
ABSTRACT: The M’zab region is subject to an arid Saharan
climate where surface and sub-surface waters are of little importance. The Albian Aquifer, commonly called Continental Intercalary (CI), main component of North Western Sahara Aquifer System (NWSAS/SASS), constitutes the most
extensive aquifer formation of the region. In our study area, the CI is identified, as a regional subset, as the Albian Aquifer of M’zab Region (AAMR). Its
groundwater resources are considered the only source available to meet the
growing needs of drinking water supply, agriculture and industry. This aquifer is heavily exploited by a very
large number of wells (more than 750). Its supply is very low, so it is a very low renewable
layer. This requires periodic monitoring and control of its piezometric level
and its physico- chemical
quality. The objective of our study is to know the current state of this
aquifer, while studying the variation of its piezometry for the period 2010-2018, and also the chemical quality of its groundwater by
analyzing more than 90 samples over the
entire study area. The application of geostatistics by kriging and the steps of analysis, modelling and calculation of semivariogram have
enabled us to draw up maps of the various hydrogeological and hydrochemical parameters.
As a result, twelve
thematic maps were gridded using Geostatistical tools of ArcGIS software. The
water-level-change map showed a significant drop in the groundwater level over
the entire M’zab
region and especially around the major cities (Ghardaïa, Berriane, Metlili and Zelfana) with more than 8 meters. Chemical analyses of the
Albian groundwater in the study area show the dominance of evaporite facies (Cl--Na+-Ca2+) with low
concentrations than the Algerian Standards for Drinking (ASD). All the water
quality indices (WQI) that have been mapped reveal that the groundwater samples
were suitable for drinking and irrigation with a high quality of water located
in the south of the study area.