Rainwater Harvesting through Point Recharge Method for Efficient Recharge of Tube Wells for Sustainable Management of Groundwater Resources in Karnataka

Abstract

Water is a precious natural resource for sustaining life, agriculture and environment. The dependability on groundwater has reached high in all time in recent decades due to reasons such as unreliable supplies from surface water due to vagaries of monsoon, increase in demand for domestic, agricultural and other purposes. Karnataka is largely dependent on groundwater to meet industrial, municipal, domestic and irrigation needs. So, Rainwater harvesting (RWH) forms an important component for development and management of water resources for domestic, agricultural, municipal and industrial uses.  Management of scanty rain fall by rain water harvesting, Augmentation of depleting natural resources of water (deeper ground water table) and Management of poor-quality ground water and scope for conjunctive/domestic use is need of the hour. With increase in withdrawal of ground water, ground water (GW) table is declining at a rapid pace with an urgent need to recharge GW in addition to dilute poor quality ground water. Double ring technique of Groundwater Recharge consists of filtering the water at different layers using gradation materials generally the pebbles of different size with synthetic material wrapped around the casing pipe. By harvesting rain water and recharging into point recharge soaking infiltration gallery established at Irrigation Water Management Research Centre, (IWMRC) Belavatagi  Tq: Navalagund has shown encouraging results as far as water quality, discharge and water table are concerned. The results of assessment of influence of ground water recharge through rainwater harvesting on ground water yield (lps), quality (dS/m) and fluctuations (feet bgl) during the year 2020, have shown that around 3.35 lakhs liters of water could be collected from rain water harvesting during the year 2020. Also, from point recharge through 7 recharge events (rain fall events from July to October 2020), it was observed that the considerable rise in the water table from more than 100 feet below ground level to around 22 feet below ground level, drastic reduction in groundwater salinity i.e. electrical conductivity (EC) of ground water from more than 10 dS/m to an average (EC) of 1.32  dS/m and tube well yield has significantly increased from 0.4 lps to around 2.4 lps. Therefore, Artificial recharge techniques through rainwater harvesting can be a better strategic approach to combat the emerging problems of water scarcity especially over exploitation of ground water and its quality deterioration.