Theme 2-5-Groundwater pollution potential assessment through drastic indices methodology - A case study for Bangalore North Taluk (Bagalore Urban District)

Abstract

Groundwater is one of the most valuable natural resources that many developing countries possess. Without improved management and closer protection, groundwater resource will suffer irreversible deterioration on a widespread basis. Innumerable large towns and many megacities derive a major component of their domestic and industrial water supply from aquifers. Approximately 65% of the total water supply is met by public supply system. The remaining 35% being individually supplied, almost exclusively from groundwater sources.

The urban runoff is highly polluted with domestic and industrial wastes that can have serious consequences for the receiving water bodies – surface and underground. In many parts of the tropics with a pronounced dry season or more generally arid climate, groundwater is also widely used as a source of primary or supplementary irrigation for agricultural development.

There is an urgent need for rapid surveys of groundwater utilisation, aquifer pollution vulnerability and subsurface contaminant load.

This situation prompted the authors to undertake a field-cum-office study of Bangalore North taluk (689 sqkm) for pollution potential assessment using DRASTIC indices methodology. This approach was originated in U.S during 1985 for assessing the levels of pollution in groundwater. It is a standardised system used for mapping groundwater pollution potential.

For the 25 grids of Bangalore North taluk, seven parameter values of DRASTIC model are applied with suitable weights and ratings and summed up to arrive at DRASTIC Indices (DI). These vary from 121-180. Higher DI value means, the area is more vulnerable to pollution. The vulnerability of different grid areas to pollution is presented on grid map of 00 2' 30'' stretch.