Spatial and temporal variability of water quality of an urbanized river in Algeria: the case of Soummam Wadi.

Spatial and temporal variations of water quality were investigated at four sites of an urbanized river in Algeria during a period of low water level in the years 2002, 2003, and 2004. Physical-chemical parameters (temperature, pH, conductivity, dissolved oxygen, suspended matter, chemical oxygen demand [COD], and 5-day biochemical oxygen demand [BOD5]) were measured. The Soummam River showed a strong pollutant load, which was organic in origin and expressed by mean concentrations in suspended matter, COD and BOD5 exceeding 150, 100, and 50 mg/L, respectively. The spatial variation highlighted two areas--(1) the first one gathers the upstream and central sites of the river, and (2) the second one is found downstream. In the downstream area, the pollutant load is almost twice as high as in the first area and, the percent saturation of dissolved oxygen is relatively weak (< 55%). This load is the result of the significant volume of urban and industrial emissions in the river, the high temperature during low-water-level periods, and flood events, which occurred just before the period of low water level. The Soummam River was classified according to the criteria of appreciation of surface water and was found to be extremely polluted. This work is one of the first studies on the quality of rivers in Algeria. This research will be useful as a first step for future works in North Africa and will add to knowledge on the water quality in the Mediterranean Basin.