Assessment of Spatial Variability in Groundwater Quality of Kurnool Region for Irrigation Purpose and Management Options

Abstract

Assessment of Spatial variability in Groundwater quality of Kurnool region for irrigation purpose and management options was conducted by collecting groundwater samples using GPS locations at various farming situations in different mandals of Kurnool district. The irrigation water quality indices were assessed to classify the ground water for its suitability based on ionic properties viz., pH, EC, Ca+2, Mg+2, Na+ and K+; CO3-2, HCO3-, Cl-and SO4-2.The pH, EC, SAR, RSC, Kellys ratio, Saturated sodium per centage and Permeability index in groundwater ranged from 6.5-8.4, 0.4-15.6 (dSm-1), 0.44-28.77 (mmol l-1)1/2, -66.8-15.4 (me l-1), 0.15-24.61, 11.04-94.89 and 17.22-111. The concentration of cations viz., Ca+2, Mg+2, Na+ and K+ varied from 0.8-24.4, 0.4-34.8, 0.5-108 and 0.003-27.6 me l-1 with mean values of 6.71, 6.19, 12.24 and 0.59 me l-1 respectively. Concentration of anions viz.,CO3-2, HCO3-, Cl-and SO4-2varied from 0-1.2, 0.4-18.2, 0.8-77.2 and 0.001-8.39 me l-1 with an average values of 0.04, 6.59, 8.78 and 1.78 me l-1 respectively. The relative abundance of ions for most of the water samples were Na+> Ca+2> Mg+2> K+ for cations and Cl->HCO3->SO4-2> CO3- for anions. Based on physico-chemical properties the groundwater is classified into good, marginally saline, saline, high SAR saline, marginally alkali, alkali, high SAR alkali for irrigation. Thematic maps representing spatial variability in groundwater quality in respect to pH, EC, SAR, RSC and irrigation water class were prepared by inverse distance weightage interpolation method using geographical information system. This will give the information of the irrigation water quality for management options in crop production.