Groundwater recharge estimation studies in a khondalitic terrain of India

Agriculture is the main occupation in the Kandivalasa river sub-basin (KRSB) covered with khondalitic terrain of Eastern Ghats of India. The farmers are mainly depending on groundwater for irrigation in non-monsoon period in the study area; as such it is important to know how much rainfall recharge is occurring to the groundwater table. The groundwater recharge is assessed in the KRSB by collecting the pre- and post-monsoon groundwater levels at 42 observation wells and rainfall data covering the entire basin during the years 2013–2016. The groundwater recharge has been calculated using both water table fluctuation method and rainfall infiltration method. The study revealed in the basin that the per cent of rainfall converting to the groundwater recharge is 11.12, 13.18, 9.51 and 12.80% for the years 2013, 2014, 2015 and 2016, respectively. The study has also revealed that the heavy rainfall events with prolonged time lead to the rise in the groundwater levels, thereby increasing the groundwater recharge. It is also observed that the deeper the pre-monsoon groundwater level, the more the recharge in the basin.