Groundwater chemical indices changed due to water-level decline, Minab Plain, Iran

Abstract

This study tried to investigate the change in the physical and chemical indices of groundwater in Minab Plain caused by groundwater level decline. In this regard, twelve groundwater samples were drawn from different wells across this plain during 22 November to 22 December 2015. The parameters of acidity, electrical conductivity (EC), and temperature and the major anions and cations were measured in situ and at the regional water laboratory of Hormozgan, respectively. Comparison of the current parameters with EC and chloride Cl−, and the measured parameters during 2006 indicated an increased concentration of EC, Cl−, sodium Na+, bicarbonates HCO3, total dissolved solids TDS, as well as total hardness TH, and a decreased concentration of sulphate SO42− over time. According to the findings in a lower groundwater quality and a higher groundwater salinity, groundwater level and reservoir capacity decreased by 11.3 m and 287.2 million m3, respectively; finally, for quality assessment of the region’s groundwater for agricultural use, values of sodium absorption ratio, sodium percentage (Na%), residual sodium carbonate, and magnesium hazard were computed; comparison of the concentrations of major cations and anions in the regional groundwater showed that the dominant cationic and anionic conditions were Na > Mg > Ca > K and Cl > HCO3 > SO4 > CO3, respectively. Comparison of the measured parameters with Iran’s national standard and the World Health Organization standards showed that the pH and calcium Ca2+ values of all samples were at desirable levels. Results suggested that the regional waters had good, acceptable, and average quality for drinking. In terms of agricultural use, the dominant cations in the regional groundwater were Na+, followed by magnesium Mg2+.