Ground water responses to recharge through rain water harvesting

Abstract

The most valuable natural resource is water, but few people are aware of the limited freshwater availability, supply and importance especially in developing countries like India. Rain water harvesting is the collection of rain water from surfaces such as roof tops in urban areas, and if it can be stored conveniently, either at surface or below the surface, it will be an economical, safe and a sustainable source of water, when it is captured and stored scientifically. An evaluation of artificial recharge on groundwater through rain water harvesting structures added to the existing buildings during 2003 in different parts of the Chennai city was done with data collected from secondary sources and field sampling and analysis. The monthly rainfall, groundwater level and groundwater quality data (2002 2006) of the Chennai city were collected to study the responses of groundwater before and after implementation of the rain water harvesting structures in the city. A total of 347,483 buildings were covered up to 2004, of which nearly half of the structures were added in the western and northern part of the city. The changes in flow directions, potential for recharge, aquifer storage and balance appear important in the designing of proper RWH systems and installation. Since groundwater modeling of the city aquifer demands more data and investigations than available, a pilot study was decided to be conducted in a smaller area but in a detailed way. This detailed field study was conducted in the campus of the St Peter s Engineering College campus, Avadi with the design, implementation and evaluation of RWH system. This experimental study showed the response of the aquifer under three different scenarios of no RWH structures, the installation of roof top structures and the addition of percolation pond and recharge wells.