Groundwater responses to artificial recharge of rainwater in Chennai, India: a case study in an educational institution campus

This paper reports the response of the groundwater in the St Peter's Engineering College campus, Avadi, near Chennai, India. Artificial recharge of rainwater was done through roof top harvesting methods during 2004 to 2007. Based on a hydro geological survey of the campus, eleven bore well were sunk for augmenting water supply to the campus. The lithology of each bore well was also recorded. A percolation pond in 1 ha area on the south eastern side of the campus was dug to collect and store the rainwater harvested from rooftops of the campus buildings. The survey also assisted in the identification and location of about 70 number of recharge wells in the campus. Pumping test was conducted in well no:3 to assess the hydraulic conductivity and calculate other aquifer parameters during 2005. A three layer hydro geological model of the aquifer was applied in Visual Modflow ver 4.1 environment and the model fit was 84% between observed and predicted values (R super( 2) = 0.844). Significant increase in water level in the top aquifer during 2007 was recorded when compared to 2004. The flow profiles in the middle and deep aquifer showed responses, through changes in the direction of flow to the pumping wells (5, 6 in 2004 and 2, 3 in 2007). In 2007, with improved recharge, changes in the direction of groundwater flow and discharge of water from the aquifer in the southern part of the campus can be noticed. The flow directions in the three aquifer layers also indicated that the northern part of the study area serves as an effective recharge zone for the St Peter's Engineering College Campus. Rainwater harvesting and recharge studies form important part in groundwater restoration and management in intensely urbanized cities/townships.