An Overview on Rain Water Harvesting

Abstract

Abstract: Rainwater harvesting, the limited collection and storage of overflow for flooded agriculture, is recognized as a sustainable strategy for ensuring food security, especially in monsoonal landscapes in the developing world. In south India, these stratagems have been used for millennia to mitigate problems of water scarcity. However, in the past 100 years many traditional rainwater harvesting systems have tumbled into shabbiness due to increasing requirement on groundwater. With raised up declines in groundwater resources, there is increased effort at the state and national levels to recuperate older systems. Critical to the success of such efforts is an improved understanding of how these ancient water-provisioning systems function in contemporary landscapes with widespread groundwater pumping and shifted climatic regimes. Knowledge is especially lacking regarding the water-exchange dynamics of these rainwater harvesting “tanks” at tank and catchment scales, and how these exchanges regulate tank performance and catchment water balances. Here, we use fine-scale water level variations to quantify daily fluxes of groundwater, evapotranspiration, and channel leakages in four tanks over the 2013 northeast monsoon season in a tank cascade that covers a catchment area of 28.2 km2. Our results indicate a different longitudinal pattern in groundwater-exchange dynamics, with the regularity and magnitude of groundwater inflow events (as opposed to outflow) increasing down the cascade of tanks. The presence of tanks in the landscape intensely alters the catchment water balance, with catchment-scale runoff rainfall ratios decreasing from 0.29 without tanks to 0.04 – 0.09 with tanks Rainwater Harvesting is a simple procedure of catching and holding rainwater where it falls. Either, we can store it in tanks or we can use it to recharge groundwater dependent upon the situation.