Ahmed Amin SOLTANI2021-10-102021-10-102021http://dspace.univ-msila.dz:8080//xmlui/handle/123456789/26860Algeria has always experienced a shortage of water resources in recent decades, and the situation has gotten worse when water quality has reached high levels of deterioration. The main objective of this thesis is to evaluate the surface water quality of a large number of Algerian dams in order to identify the most contaminated areas of the country and the factors that may lead to that. The present contribution has been divided into two-fold. The first study is devoted to assessing the water quality of forty-seven (47) dams, described with 10 Physico-chemical parameters, during 11 months (2019), and located over the four principal northern watersheds using a newly developed Water Quality Index based on the Data Envelopment Analysis (DEA-DQI) approach. The results of the proposed index revealed that 21.27%, 27.66%, 25.53%, 4.25%, and 21.27% of all dams are classified as " Poor", "Marginal", "Average", "Good", and "Excellent" water quality, respectively. The best water quality is found in the "Kissir" dam and the worst one in the "Bougara" dam. It is noteworthy that the dams with the worst water quality are located in the Oranie-Chott-Chergui watershed (OCC), in the western region, due to uncontrolled municipal-industrial discharges and agricultural fertilization practices. These results can also be interpreted by the agent of drought due to the impact of climate change. Among all the selected dams, Beni Haroun (BH) dam has been studied separately as a specific case in the second part of our contribution, given its major importance in the country. Under the same framework of an integrated approach with a dataset of 22 parameters observed during 11 years (2000-2010), several methods were employed, including the Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), Principal Component Analysis and Factor Analysis (PCA/FA), K-means clustering and Ordinary Least Squares (OLS) to perform a comprehensive assessment of the water quality of BH dam and its upstream viz. Wadi Rhumel (WR). CCME-WQIs showed that BH dam is characterized by "Poor" water quality for drinking, irrigation, industry, and aquatic life, with indices of 17, 40, 42, and 32, respectively. Besides, K-means algorithm shows a clear similarity in water quality between BH dam and WR, which indicates it is the main pollution source of the dam's water. PCA/FA found that the water quality of BH dam is influenced by two major pollution factors: (i) natural processes and (ii) non-point source anthropogenic pollution. The most impressive finding of such a study is certainly the positive trend in WQIs using OLS, which is rather promising.Surface water; Water quality; WQI; Dam; Beni Haroun; Pollution; AlgeriaThesis