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2 Ecological Engineering & Environmental Technology

2 2025

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Effect of hydraulic fracturing of shale gas reservoirs on groundwater in Algeria

Bounoua Rabah, Yebdri Djilali

Ecological Engineering & Environmental Technology

2025

Vol. 26, iss. 2

27--44

The exploration of shale gas reservoirs in Algeria has led to significant debate in the oil and gas sector due to potential risks to the country’s declining water resources. This study focuses on assessing the risk of groundwater contamination from hydraulic fracturing (HF) in the Algerian southeast region, where the Frasnian shale gas reservoir lies between 3575 m and 3720 m deep, and the nearest aquifer Lias Horizon B is located at 1572 m. A model was developed using MODFLOW software, incorporating the characteristics of the geological layers traversed by well P-1, recently drilled in the region. A hypothetical, homogeneous, and continuous permeable pathway connecting the top of the Frasnian reservoir to the Lias Horizon B aquifer was included in the model. The study is based on simulating a reference scenario to which values observed in the region were assigned for factors influencing the migration of HF fluid. Subsequently, due to incomplete data regarding the real-world case study, a sensitivity analysis was conducted through the simulation of 11 scenarios to evaluate impact of each factor. The tracking of HF fluid pathways was performed using MODPATH software. The results show that HF fluid can reach the aquifer in 99.05 years. Sensitivity analysis identifies key factors in HF fluid migration, including the hydraulic conductivity of the permeable pathway, the fractured shale, and the extent of the induced fracture. In contrast, the lack of a permeable pathway and the limited length of the induced fracture prevent any migration of HF fluid to the aquifer.

Calculating point runoff in the arid catchment areas of the Western Saharan Atlas: Case of Wadi Rhouiba catchment area (Ksour Mountains) in south-western Algeria

Benbouziane Zoulikha, Yebdri Djilali, Cherif El Amine

Ecological Engineering & Environmental Technology

2025

Vol. 26, iss. 3

378--392

In Algeria, frequent peak flows are currently estimated using empirical or analytical formulas established under geographical and climatic conditions other than those of Algeria, which is known for its spatial and climatic diversity. As a result, the errors committed by these extrapolated formulas can reach considerable values, leading to poorly dimensioned and erroneous flood protection structures. In this context, light was shed on the calculation of frequency flows and their appropriate adjustment tests in one of the arid to desert regions of the Wadi Rhouiba basin, part of the Western Saharan Atlas (Ksour Mountains region), south-west Algeria, based on instantaneous flow data measured at the Ain Hadjadj hydrometric station and empirical models. In this study, the authors confined themselves to the general characteristics of floods, such as their genesis, power and frequency, and to the hydrological potential and risks they represent. The catchment area covers a surface area of 2945.74 km2, perimeter of 389.23 km, elongated shape (Kc = 2), very steep slopes exceeding 35%, favoring strong, rapid runoff, with a runoff concentration time (Tc = 21.21 h). All these conditions have contributed to classifying the basin as an arid to desert bioclimatic zone, offering a favorable environment for the development of heavy floods. Surface runoff in this arid region is closely associated with local rainfall patterns on the one hand, and the specificity that the region is landlocked between a series of barren mountains, on the other. Peak flows are considerably higher than average flows. These cures are rapid, characterized by an abrupt rise in water levels during the flood phase and a slower decrescence with a prolonged drying-up. Autumn is identified as the season with the greatest risk of flooding. Discharge during low-water periods bears witness to the phreatic potential generated by the Atlasic nature of the study region, highlighting a significant hydrological relationship between surface water and groundwater. The Exponential law gave the best fit of the maximum daily rainfall series from the Wadi Rhouiba watershed station, which are close and satisfactory to those of the flows calculated by Sokolovsky’s empirical formula, which can then be readily exploited for the sizing of protection structures in arid to desert regions.