Hydrochemical characteristics and water quality evaluation of the Srou River and its tributaries (Middle Atlas, Morocco) for drinking and agricultural purposes

The present study was conducted to evaluate the surface water quality of the Srou River and its tributaries for drinking and agricultural purposes. For this, 18 parameters including temperature, pH, electrical conductivity (EC), turbidity, total hardness (TH), dissolved oxygen (DO), chlorides (Cl), sulfate (SO42–), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), carbonates (HCO3-), nitrate (NO3-), nitrite (NO2-), ammonia (NH4+), and trace elements were monitored on 12 sampling points. The results showed that EC, TH, Cl–, SO42–, Ca2+, Mg2+, Na+, and some heavy metals such as Al, Cd, Fe, and Pb exceed widely the Moroccan and WHO standards for drinking water. The pH, DO, K+, NO3-, NO2-, and NH4+ contents are within the Moroccan and WHO guidelines for drinking water. Therefore, we concluded that the Srou River was potentially unsafe for drinking and domestic use. The abundance of cations and anions were in the order of Na+ > Ca2+ > Mg2+ > K+ and SO42–- > Cl- > HCO3- > CO32- that leads to Cl-, SO42–, Ca2+, Mg2+ hydrochemical facies type. The multivariate statistical methods including Pearson’s correlation, principal component analysis, and cluster analysis show that the variations in water compounds’ concentration are mainly related to the effects of the lithology of the basin (weathering of soil, rock, and leaching of minerals). The SAR, salinity, KI, and MH were also used to assess the river water quality for agricultural purpose. The sodium absorption ratio, KI, and MH values suggested that the Srou River water had an acceptable quality for irrigation. However, high salinity values indicate that these waters could pose hazards in irrigated soils and should not be used for irrigation without special management plan.