Professor, Department of Geography, University of Madras, Chennai
Research Scholar, Department of Geography, University of Madras, Chennai
Assistant Hydrogeologist, TWAD Board, Chennai
The importance of water is felt in all sectors as the demand and needs of the populace is growing. The groundwater exploitation is taking leaps and bounds as an alternative to dried up surface sources. The groundwater levels are dwindling to deeper depths in many parts of Tamil Nadu and there is an urgent need to think of strategies for groundwater conservation and management. Keeping this as an objective, the suitable sites for artificial recharge in hard rock environs are identified using an integrated approach of Remote sensing and GIS.
The Study area is Upper Kodavanar River Basin in Dindigul District, Tamil Nadu, located in between 10° 15′ N to 10° 30’N Latitudes and 77°30′ E to 78° 15 E Longitudes, falling in SOI Toposheets 58 F/11,15,16 and 58 J /3,4 with an areal extent of 1,135 km2. Hard crystalline gneissic rocks challenging a difficult task to identify appropriate artificial recharge sites predominantly underlie the study area. The aquifer beneath is heterogenetic in nature and the groundwater distribution is also not uniform. Much care has to be taken while locating suitable sites and in such circumstances spatial and aspatial data are essential that could be integrated using GIS package ArcInfo and ArcView. The most important and relevant parameters that are suitable for recharge are only considered for integration.
The methodology adopted in the present study includes preparation of surface drainage map from SOI toposheet and satellite data on 1:50,000 scale. This linear drainage map has been converted into drainage density using grid of 1 km * 1 km where the values are contoured by SURFER and taken for integration in ArcInfo environnment. Similarly Slope map has been prepared from Toposheet on 1:50,000 scale adopting IMSD guide lines. Soil map has been prepared visually interpreting the IRS LISS II data and classified based on their Hydrological Characteristics. Similar to that of drainage density, Lineament density was prepared from Lineament map interpreted from satellite data and the values in grids of 1 km * 1km are contoured With SURFER and exported to ArcInfo for integration. The other parameters such as pre-monsoon water level, topsoil, weathered, fractured thickness, and water quality (Total dissolved Solids) are contoured and used for integration. Criteria for GIS analyses has been done on the basis of Delphi concept (Consensus approach) and weightages have been assigned to each theme based on the significance. The recharge potential map generated through the integration of ArcInfo and recommendations are made village wise. The site-specific criteria attempted in this study could be implemented and could also be extended to the other areas of similar hydrogeological set up. The study manifests the importance of surface and subsurface data while selecting the recharge structures like check dams and percolation ponds for sustainability and improvement of groundwater.