Surface water of Kébir Rhumel basin is indispensable for domestic and industrial needs of this region. Industrial development, with water excessive use and chemical products, in production and industrial treatment, and not sustainable ferti-lizers in agriculture, constitutes a serious threat to maintain our resources of good water quality. The majority of domestic and industrial wastewaters of the region, discharged to the stream water of Kébir Rhumel basin, promote the water enrich-ment in nutritious elements, phosphorus and nitrogen and particularly, the resulting increase in the aquatic primary produc-tion, mainly the planktonic or benthic algae. As a result, the physical and chemical properties of water deteriorate.

This basin allows construction of the largest dam in Algeria “Beni-Haroun dam”. The infrastructure that was one of the greatest challenges of Algeria is now a reality. Hydraulic complex of Beni-Haroun remains a strategic and major achievement in the development program of water resources sector. This enormous building was constructed in the territory of the Wilaya (province) of Mila, used to meet water needs, with four million inhabitants, of eastern Algeria and other neighbour-ing regions that have suffered from lack of water consumption, especially in summer. In addition, it will irrigate over 42 000 ha, going thus to the several plains.

Integration of sociological and environmental concerns into dams design is a recent phenomenon. It is considered at the impact study level, during which the dam study project is accompanied by a survey to assess project impact on natural en-vironment and socioeconomic development.

The unique oasis of Zousfana, on the western edge of the Grand Erg Occidental, Taghit is the pearl of the oases of Saoura, a palm grove of 180 ha over an 18 km length crossed by Oued Zouzfana. It regroups the different types of landscapes of an arid zone (erg, hamada, barga – a small hill, oued ...). Taghit is known for its hydraulic civilization, the oasis in its hostile environment has survived thanks to the exploitation of rare groundwater irrigation according to the traditional customs applied to the whole of society. The peasants spur out the water resources through foggaras and traditional wells. But the intervention of modern irrigation techniques in an anarchic way has disrupted the fragile mode of irrigation and the abandonment of the palm grove. The over-exploitation of groundwater by the use of boreholes and motor pumps leads to the drying up of water sources, mists and traditional wells. Today, only 45 000 palm trees are productive and less than 1500 fruit trees. There are 500 fellahs in the entire agricultural area of Taghit, the majority of them is fleeing work in the oasis because of the lack of income from it. When comparing the results of analyses from different campaigns (2015 and 2008), a spectacular increase in the salt concentrations in the groundwater of the different palm groves is noticed. According to our investigations, the main causes of this jump are: the overexploitation of the water tables by motor pumps, the abandonment of land inside the palm grove, the lack of maintenance of the gardens, the exploitation of domestic wastewater in the irrigation. According to this preliminary study, it is important for the State to make farmers aware of the role of their traditional irrigation systems in the continuity of the oasis and life in it.

The study deals with the assessment of the solid transport in the wadi Mouillah watershed (Tafna, Algeria). Sediment transport is a complex phenomenon. The quantity of sediment transported is very important, and it fills in the reservoirs. The scale is out of proportion in semiarid areas. Algeria is one of the most affected countries by this phenomenon. A simple method, based on average discharges, easy to implement, has been developed for estimating the sediment yield using dou-ble correlation method (a first one between liquid discharge – solid concentration and a second one between solid flow – concentration). It is based on hydrometric data (liquid flow, concentrations and sediment discharges) with applications analysis on seasonal and annual scales for data’s of Sidi Belkheir station at the outlet of the wadi Mouillah watershed (North-West of Algeria). The obtained results by the application of this method are very encouraging because of the quite significant correlation coefficients found (≥59% for the first correlation and ≥88% for the second correlation). The water-shed of Mouillah produces between 43 730 and 56 410 Mg·y–1 as suspended sediment load against 48.56∙103 to 53.3∙103 m3·y–1 of liquid intake.