Irrigation water quality appraisal using statistical methods and WATEQ4F geochemical model

Abstract

Abstract The irrigation water suitability analysis is not very common in developing countries, and it has a significant impact on crops. The present study focuses on the assessment of the suitability of well water of Prayagraj district, Uttar Pradesh, India. The groundwater sample datasets of 2018 were collected. Water quality indices namely Sodium Adsorption Ratio, Exchangeable Sodium Percent (SSP or %Na), Residual Sodium Carbonate (RSC or RA, Kelly s Ratio, Permeability Index, Chloroalkaline indices, Potential Salinity, Magnesium Hazard, Total Dissolved Salts and Total Hardness (TH) have been calculated for separate bore wells. The WATEQ4F geochemical model was also used to assess the irrigation water suitability. Hierarchical clustering analysis (HCA) has resulted in three groups due to the processes on natural and anthropogenic factors. The principal component analysis has shown that PC1 explains 34.066% of the total variability and PC2 accounts only for 20.65%, PC3 accounts for 14.29%, PC4 for 9.62% and PC5 for 7.44% with cumulative variance 86.088%. The r1 and r2 index shows that groundwater of study area is Na+–SO42− and deep meteoric percolation (DMP) type. Generally, the minerals like anhydrite, brucite, epsomite and gypsum solutions showed high to very high degree of undersaturation, which indicates that they are affected largely by the dilution. Aragonite, calcite, dolomite c and d and magnesite minerals were saturated with respect to water. Majority of the wells fall under moderate to suitable category of water for irrigation purposes. Further, well water has also been classified on the basis of meteoric genesis index.