Assessment of Spatial Distribution and Temporal Variations of the Phreatic Groundwater Level Using Geostatistical Modelling: The Case of Oued Souf Valley—Southern East of Algeria

Abstract

Since the beginning of the 1980s, several regions in the northern Sahara of Algeria have been confronting the rising groundwater. Among all these regions, Oued Souf Valley represented one of the most acute affected by this phenomenon. Due to the natural topography and the insufficient/weakness of water management and miscoordination between different sectors that are represented by intensive exploitation of deep groundwater reservoirs which returns to the shallow aquifer, absence of sewage and drainage network, leakage from drinking water supply system, the groundwater has raised to the surface or near to the surface, affecting the traditional cultural environment and urban areas and degrading all socio-economic aspects of the Oued Souf habitants. To preserve the Oued Souf environment, a vertical drainage system has been constructed. Consequently, in this research, an evaluation of the vertical drainage system performance and its impact on groundwater level stabilization has been performed by mapping the water table of the phreatic groundwater level using geostatistical modeling using ordinary kriging (OK) interpolation method, which has been applied to analyze the spatial and temporal structure of groundwater level fluctuation. Meanwhile, hierarchical cluster analysis (HCA) was applied for grouping the wells based on the groundwater fluctuations for 2008, 2009, 2014, 2016, 2018, and 2021. However, the vertical drainage system reflected a significant decline of groundwater from 2009 to 2018 due to the important drained volumes through it but another rising phenomenon might be threatening the region in the near future and this is what was indicated in the 2021 groundwater level data. Cluster analysis has generated four groups based on their fluctuation means that are increasing from the first group to the fourth group ascendingly. The first cluster grouped the drains that have a shallow depth (average mean of 5.91 mbgl) and declined over the clusters. The clusters are spatially combined with significant separation of the fourth cluster which represents the deepest group (12.89 mbgl). Based on this research, several factors are influencing the stability of the phreatic groundwater level and even the performance of the drainage system, the most important of which is the overexploitation from deep groundwater reservoirs such as complex terminal and continental intercalary (in drinking and irrigation) and even the illegal use of the phreatic groundwater with important quantities for irrigation and illegal industries.

The integration of geochemical and isotopic approaches for thermo-mineral water characterization: the case of Tebessa (North Eastern Algeria)

“…The two water groups are essentially plotted in the Ca smectite and kaolinite stability fields. Therefore, the balance between Ca smectite and kaolinite is one of the major processes regulating the chemical composition of water in the study area (Barkat et al, 2022; Mineral stability diagrams are first used to identify the reactions that mechanism the chemistry of water. Figure 6 reveals mineral stability fields for a weathering kaolinite system (Na 2 O-Al 2 O 3 -SiO 2 -H 2 O), indicating that equilibrium with this mineral phase is one of the main processes controlling groundwater chemistry.…”

The Integrated Use of Heavy-Metal Pollution Indices and the Assessment of Metallic Health Risks in the Phreatic Groundwater Aquifer—The Case of the Oued Souf Valley in Algeria

“…The Oued Souf region is surrounded by various areas: it lies to the northeast of Tebessa, east of Tunisia, northwest of Biskra, north of Khenchla, and to the west and southwest, it shares boundaries with Djelfa and Ouargla, respectively. According to climatic research conducted by [37], which analyzed 42 years of data (1978-2020) collected from the Geumar meteorological station in Oued Souf, the study area is characterized by an extended dry period throughout the hydrological year and a bioclimatic stage of Saharan vegetation. The irregularity and scarcity of precipitation, coupled with high temperatures and extremely high evapotranspiration, have had a significant impact on surface run-off and infiltration, limiting the region's ability to contribute to the natural recharging of underground reservoirs.…”

Hydrochemical assessment of groundwater using multivariate statistical methods and water quality indices (WQIs)

“…Numerous techniques have been developed and utilized by researchers to study and characterize the spatiotemporal variation of groundwater physicochemical parameters, including multivariate statistics, geochemical modeling and water quality index (Barkat et al 2021(Barkat et al , 2022(Barkat et al , 2023Bouteraa et al 2019;Chabour et al 2021;Chen and Feng 2013;Foued et al 2017;Hamed et al 2022;Lekrine et al 2023;Mohamadi et al 2021;Derdour et al 2023).…”