Influence of Monsoon on quality of water in lakes of Chota Nagpur plateau, North Eastern India

Abstract

Indian agricultural, politicaland social structure is hugely impacted by the variability in monsoon. In recent times, unprecedented irregularities have been witnessed by Indian Metrological Department (IMD). Lakes and natural reservoirs in plateau are extremely dependent on monsoon, therefore, minimum alteration also translates in huge deviation in quality of water. In this study, an attempt has been made to examine alteration in quality of water during pre-monsoon, monsoon and post-monsoon. It was also assured that how population and urbanization impact monsoon runoff and change in physicochemical characteristics. Two lakes, namely Kanke lake and Ranchi lake were selected due to its urban and semi-urban localization, respectively. Physicochemical characteristics were examined accordingto APHA guidelines. Our results indicated significant alteration (p<0.05) in pH (7.32±0.17), DO (4.27±0.47 mg/l), and phosphate (0.19±0.01 mg/l) of Kanke lake post-monsoon. Whereas, minimum significant alteration was observed in Ranchi lake post-monsoon. Level of DO (10.39±0.44) significantly changed (p<0.05) in Ranchi lake following depletion in monsoon. However, level of hardness and BOD altered significantly (p<0.05) comparing to pre-monsoon during both monsoon and post-monsoon. Monsoon impacted physicochemical properties of both lakes, however, more alteration was evident in Kanke lake comparing to Ranchi lake. Eutrophication in both lakes were observed due to potential anthropogenic acidification. This study observed that semi-urban lakes are more vulnerable to encroachment and eutrophication comparing to urban lakes.