ABSTRACT
This abstract summarizes the preliminary results from groundwater recharge estimates at Kolkata, West Bengal, which is under the Kolkata Metropolitan Corporation (KMC) covering an area of 187.33 sq.km. Water is indispensable to all life on earth. However, freshwater is constantly formed newly through a phenomenon known as hydrological cycle. Groundwater is the source of about 33% of the water that county and city water departments supply to households and businesses. Groundwater recharge is the process by which water percolates down the soil and reaches the water table, either by natural or artificial methods. Here, natural groundwater recharge is dealt with. Quantification of the rate of natural groundwater recharge is a pre-requisite for efficient groundwater resource management. For a region like Kolkata, there is large demand for groundwater supplies, where such resources are the keys to economic development. However, the rate of aquifer recharge is one of the most difficult factors to measure in the evaluation of groundwater resources. Estimation of recharge, by any method, is normally subject to large uncertainties and errors. In this study, various methods of estimating natural groundwater recharge in Kolkata region (2016) are outlined taking one year precipitation and evapotranspiration data, calculating the runoff of this region and getting the net storage capacity of soil, which is mostly alluvial. This study estimates the amount of recharge taking place in Kolkata and it critically reviewed with regard to their limitations and associated uncertainties leading to the need for artificial groundwater recharge by roof-top rainwater harvesting. And finally, a detailed design for a rooftop rain water harvesting system is provided.
