Spatial and Temporal Water Quality Analysis of a Semi-Arid River for Drinking and Irrigation Purposes Using Water Quality Indices and GIS

Aims: This study aimed to assess the water quality of Ardak River and analyze its suitability for drinking and agricultural purposes. Materials Methods: In this research, water samples were collected during dry and wet seasons in 2018 from previously selected 5 sampling stations. Then, the water quality index (WQI) and irrigation-related indices were calculated. Findings: The calculated WQI values are between 156.77 and 379.59 in the study area, which shows the water quality of Ardak River is in the ldquo;poor rdquo; to ldquo;unsuitable for drinking rdquo; range both periods. The effects of water quality parameters on the WQI were evaluated, and the obtained outcomes indicate that the highest mean effective weight value belongs to the fecal coliform and phosphate parameters compared to the other parameters. Furthermore, various indices such as sodium adsorption ratio (SAR), residual sodium carbonate (RSC), magnesium hazard (MH), Kelly rsquo;s index (KI), and Permeability index (PI) were used to assess river water quality for irrigation purposes. The results indicate that the river water quality is generally moderately suitable to safe with exceptions at a few sampling stations in the dry season, which are unsuitable for irrigation purposes. Conclusion: Due to the negative effects of anthropogenic pollutants such as animal husbandry, intensive agricultural activities, and rural wastewater discharging, the water quality of the Ardak River is deteriorating. Therefore, necessary protection steps should be taken in the Ardak Watershed.