Failure of a Vertical Drainage System Installed to Fight the Rise of Groundwater in El-Oued Valley (SE Algeria): Causes
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TECHNICAL ARTICLE—PEER-REVIEWED
Failure of a Vertical Drainage System Installed to Fight the Rise of Groundwater in El-Oued Valley (SE Algeria): Causes and Proposed Solutions Salim Khechana . Abdelmonem Miloudi . Ali Ghomri . El Habib Guedda . El-Fadel Derradji
Submitted: 30 August 2015 / in revised form: 20 November 2015 ASM International 2016
Abstract El-Oued Valley suffers from the problem of rising groundwater which affects agricultural and urban areas and degrades all aspects of the socioeconomic life of its inhabitants. This problem, which appeared in the 1980s, is primarily a result of overexploitation of deep groundwater, lack of sanitation network, and discharge of wastewater directly into the unconfined aquifer. To solve this problem, a megaproject was carried out, based on the principle of sewerage, to drain and evacuate excess water after treatment to a discharge site 70 km north of the region. In this project, the blade of groundwater above elevation of 60 m should be drained through wells of a vertical drainage system. However, the expected results have not been achieved in most affected cities, where the groundwater level continues to rise. Herein, we propose a solution to this problem, based on a new explanation of the hydrogeological structure of the unconfined aquifer that drives the rising groundwater to the surface. The main part of this research is based on interpretation of well tests carried out in wells of the vertical drainage system. Keywords El-Oued Valley Rising groundwater Unconfined aquifer Vertical drainage system Hydrogeological structure Well tests
Introduction Groundwater is an important source of fresh water for humans, animals, and plants on Earth [1]. Unfortunately, several Algerian regions, especially those located in the Sahara, today face problems related to quantitative and qualitative aspects of water resources, mainly due to rising groundwater from aquifers, which is harmful to agriculture and habitats [2]. This problem has negative consequences for the environment and health, as shown by Photos 1 and 2 [3]. To date, hydrogeological studies analyzing this rising groundwater phenomenon have assumed that the aquifer is homogeneous and formed only by sands characterized by high hydraulic conductivity [4]. However, in reality, the aquifer is heterogeneous, consisting of layers of clay, marl, and gypsum. The failure to account for such heterogeneity has led to misinterpretation of pumping test results, in turn influencing the design of well tubes and the position of their screens. This paper reports new understanding on the rising groundwater phenomenon in El-Oued Valley, based on analysis of well test data, which indicates that the unconfined aquifer is composed of two layers, probably separated by lenses of clay and sometimes sandy clay.
S. Khechana (&) A. Miloudi A. Ghomri E. H. Guedda Faculty of Sciences and Technology, El-Oued University, P.O.B 789, 39000 El-Oued, Algeria e-mail: [email protected]
Methods and Materials
E.-F. Derradji La
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