Impact of rock-water interaction on hydrogeochemical characteristics of groundwater: Using multivariate statistical, water quality index and irrigation indices of chachro sub-district, thar desert, sindh, Pakistan

Twenty-six groundwater samples from the dug well aquifer were collected during April 2021 from the Chachro sub-district, Sindh, Pakistan to know the hydrogeochemical characteristics and groundwater quality for domestic and agricultural purpose. Multivariate statistical, Chloro alkaline indices result and scatter plots confirm the ion-exchange process in the study region. The Gibbs diagram indicated that rock weathering and evaporation were significant processes that control groundwater chemistry. Piper and Chada's diagram suggested that ground-water was Na+, K+, Cl-, SO4-2 type and suggested that alkali exceeds alkaline earth metals and strong acidic exceeds weak acidic anions. PCA and correlation coefficient reveal that TDS, EC, Mg+2, Na+, Cl-, SO(4)(-)2 were positively correlated and similar is confirmed through HCA. The statistical results reveal the dominant decreasing order amongst the cations Na+>Ca+2>Mg+2>K+ and in anions, Cl- > HCO3 > SO4. Based on the DWQI, 50% were unsuitable for drinking. Wilcox and USSLH diagram reveal that most samples clustered in very high salinity and very high sodium water type were not suitable for agriculture use. Sodium absorption ratio (SAR), Kelly's ratio (KR) and Sodium percentage Na% reveal that most groundwater samples were unfit for agriculture use. However, Residual sodium carbonate (RSC) and Results of permeability index (PI) were suitable for irrigation purposes.