Rainwater Harvesting an Instrument to Improve Ground Water Quality and Quantitative Potential: The Case Study of Dwarka Sub-City, Delhi

Abstract

Dwarka scheme part of the Urban Extension of MPD-2001 of National Capital Territory of Delhi, has been planned to cater to the ever increasing housing requirements of Metropolitan Delhi. Dwarka Sub-City with a total geographical area of 5648 Ha is located in South-Western part of Delhi. The area is envisaged to become a model Sub-city of the 21st century and to house 13 lakhs people. The area is developing fast with more than 400 Group Housing Societies & 11000 DDA Residential Freehold Flats (in Four and Multistory Buildings), 3100 Residential Plots, housing colonies apart from commercial complexes, District centers, public places etc. The area with present population of 5 lakhs roughly is in severe grip of shortage of the supplied water, as it receives only Rs 2.8 MGD from the concerned water supply agency, against the requirement of 10 MGD. In view of this the balance water demand of its residents for domestic & non-domestic uses is mostly met from the Ground Water. The rampant extraction of Ground Water by Government & private authorities, has led to the depletion of fresh water layer and decline in the water table at very fast pace in last few years, raising questions about its future availability. This paper focuses on the methodology of Ground Water Restoration by way of recharging it with the rainwater, which otherwise goes water and leads to flooding / public havoc. The feasibility & need for implementation of Ground water Recharge Scheme in the area was established through the detailed study & analysis of the factors governing the Ground Water Discharge & Recharge in the area: such a Ground water Level behaviour, Ground water Quality, Rainwater quality, Rainfall Intensity & its distribution, Ground Water & Rainwater Potential, Aquifer Geometry & Characteristics and Ground Water requirement of the area. The Depth to Water level measured at different locations in the area was utilized to study the annual & Pre-Post Monsoon water level fluctuations. Thereafter the impact of Rainwater Harvesting on the Ground Water Quantitative Potential was established based on the mathematical calculations. The study established that the ground water restoration through artificial recharge technique would to some extent help in mitigating water crises in