Assessment of water quality at the largest dam in Algeria (Beni Haroun Dam) and effects of irrigation on soil characteristics of agricultural lands

Beni Haroun Dam is a vital water resource for both potable water and irrigation in eastern Algeria. This study assessed water quality at the dam and investigated the impacts of this water on some soil characteristics of irrigated lands. The physicochemical parameters of the water were measured monthly at eight sites and related to soil characteristics sampled from six irrigated areas, which were compared to non-irrigated soils. The chemical facies of the water were chloride sulfate and calcium magnesium. The water had low levels of cadmium (8.9 mu g/L) and lead (4.55 mu g/L), excessive contents of chloride and bicarbonate, while pH ranged between 6.5 and 8.4. High levels of electrical conductivity were measured in 39% of samples that exceeded standard for irrigation use. Richard diagram identified four classes of water: (i) C3S1 with 61.5% of samples having moderate or poor quality, (ii) C4S1 (30.2%) having poor or bad quality, (iii) C4S2 (5.2%) having very bad quality, and (iv) C5S3 (3.1%) determined unsuitable for irrigation. A Wilcox diagram revealed that 58% of samples had good quality while 42% were inappropriate for irrigation. Soil pH, EC and OM increased in irrigated soils, particularly in the surface horizon, compared to the control sites; whereas total CaCO3 decreased at all soil depths measured. High levels of bioavailable lead (35.82 mu g/g) and cadmium (0.22 mu g/g) were recorded in the surface soil. The study suggests that adequate protection measures with appropriate guidelines for various water and soil parameters are needed to minimize the detrimental effects of irrigation water on agricultural lands. (C) 2018 Elsevier Ltd. All rights reserved.