Assessment of vulnerability and hydrogeochemical specifications of Bahabad Yazd Plain aquifer

Available quality groundwater resources are declining globally due to population growth, agricultural activities, industrialization, and urbanization. Wells in Bahabad Plain, located in Yazd Province, Iran, are the primary source of water demanded by humans for drinking and agricultural activities. Hence, it is pivotal to examine the quality of groundwater resources, which is the main objective of this study. To this end, seventeen water samples collected in the region were using standard sampling methods, and ten parameters were examined from the samples, namely pH, TH, TDS, SO₄, HCO₃, Cl^-, K⁺, Ca⁺, Mg⁺, and Na⁺. Water quality index (WQI) was used to determine water quality, and SI, GODS, and DRASTIC methods were used to examine aquifer vulnerability to contamination. Schoeller's diagram indicated that 11% of the samples were at an excellent level; 33% were at a drinkable level; 20% were at a not-suitable level for drinking; 26% were terrible for drinking; and 10% were at an almost non-drinkable level. According to WQI results, 23.53% of the samples had no limitation for drinking, 35.29 were of low quality, 17.65% were of inferior quality, and 23.53% were non-drinkable. The GODS method results indicated that the eastern, central, western, and small parts sporadically scattered in northern regions of the study area (39.93%) had a moderate vulnerability. Lastly, a significant portion of the northern and southern districts (60.07%) was found to have a low vulnerability to contamination, which was in line with WQI results.