Hydrochemistry and water quality assessment of the maroon river in Behbahan area, SW Iran

Abstract

Assessing water quality is important in optimizing water usage. In this study, six water samples were taken from points along the Maroon River in order to evaluate its quality. The concentrations of Cl-, SO2-4, HCO-3, CO2-3, NO-3, K+, Mg2+, Na+, and Ca2+, as well as pH, electrical conductivity (EC) and total dissolved solids (TDS) were measured. The results were compared with the WHO (World Health Organization) drinking water guidelines and the FAO (Food and Agricultural Organization of United Nations) standard for irrigation water. The values of EC, TDS, Ca2+, Cl- and SO2-4 in two samples, and that of Mg2+ in one sample from downstream exceed WHO recommended limits. The K+, Na+ and NO-3 concentrations are below the WHO limits. The dominant water facies is bicarbonate-calcium (HCO3-Ca). A Schoeller diagram shows that the water samples are of ‘Good’ and ‘Intermediate’ classes, while a Wilcox diagram reveals that the water is in classes C2S1, C3S3 and C3S2 - i.e., ‘Good’ or ‘Intermediate’ - for agricultural purposes. The water quality indices %Na, sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), magnesium adsorption ratio (MAR) and Kelly’s ratio (KR), also indicate that the water is suitable for irrigation. In terms of EC, the water samples are of ‘Good’ and ‘Permissible’ quality. Geochemical investigations show that the water chemistry is influenced by evaporation, dissolution of evaporitic minerals, ion exchange and human activities.