This work involves the study of hydrological characteristics of the groundwater of Oued M'zab, due to the domestic, agricultural, and industrial pollution. The different sampling points are located upstream and downstream of the river. Water samples of groundwater were taken monthly at stations spread over the flow of the river. The wells are distributed throughout the course of the flow of the river. The measured hydrological parameters (temperature, salinity, suspended particles) showed significant monthly variations with a high concentration of total suspended solids which reached 71.72 mg \ l. The same results indicate that the groundwater is rich in minerals and nutritious elements while on the set of sampled points only salinity showed significant variations. The maximum value of the sulphate with a concentration of approximately 2597mg \ l. The chlorides and sodium concentrations reach respectively the values of 1633 mg \ l and 1970 mg \ l. This indicates that the infiltration of water of M'zab contains several pollutants contributing to the degradation of the quality of groundwater, Hence the need for preventive measures, conservative and prospects to preserve our layer from pollution.

In order to protect the environment and the groundwater against pollution, we dealt with one of the problems in the world, regarding the treatment of wastewater and the possibility of reuse with irrigation. We studied the case of the Kef Eddouken natural lagoon treatment plant in Ghardaia (southern Algeria). For this reason we studied the physico-chemical, bacteriological and parsitological parameter of waste and treated water. The results of the analysis show that all the previous parameters comply with the Algerian standard of rejection except electrical conductivity, suspended matter and BOD5. On the other hand, despite the electrical conductivity exceeds the limit, but it corresponds to the SAR value; according to the Algerian and the international standard of irrigation, this quality of water can be used sub-irrigation for vegetable which eaten only cooked.

The present work aims to assess the groundwater quality using Water Quality Index (WQI), which can be considered as major factor for controlling quality of water with regarded to drinking purposes. Water quality index is used to illustrate the general state of water quality in a single number. This study concerns specifically Daia area upstream region of M'zab valley. Water samples have been collected at eighteen groundwater points in two years 2016 and 2017. Then, different parameters are analyzed and compared with Algerian standards for drinking water. The hydrochemical study shows significant variations in physico-chemical measurement. Also, the obtained results of the water quality index in Daia region show an excellent ranking with 94%, 88% in years respectively.