Assessment of groundwater quality for drinking purposes in Amaravathi river basin

Groundwater assessment has become a demanding issue due to the scarcity of freshwater. Heavy textile based industrialization in Amaravathi river basin has caused over exploitation, decline in water levels and deterioration of water quality. Pre and Post monsoon analysis of samples from 31 observation wells over the period of thirty years (1988-2017) revealed that pH (8.18-8.22), Ca (67.87-73.79 mg/L), SO4 (122.37-125.64 mg/L), HCO3 (226.36-243.85 mg/L) and F (0.31-0.42 mg/L) are within the admissible limits and EC (0.05-0.50 d Sm-1), TH (489.4-518.29 mg/L), TDS (1021-1022 mg/L), Cl (304.68-306.51 mg/L), NO3 (24.90-26.21 mg/L)and Mg (78.76-82.75 mg/L) exceeds the admissible limits for the entire basin during Pre and Post monsoon periods. The quality of groundwater is classified as excellent (100) for human consumption based on the calculated Water Quality Index values (WQI). Hydro chemical assessment of groundwater quality for domestic and drinking utility were worked out using WQI and ranged from 8.1 to 56.8 during Pre monsoon and 9.0 to 66.7 during post monsoon periods, indicating the water quality of excellent to poor and excellent to very poor categories for potable purposes during pre and post monsoon respectively. Instantaneously some proportion of excellent water quality wells are shifted into good quality wells over three decades.