Evaluation of local groundwater vulnerability based on DRASTIC index method in Lahore, Pakistan

Abstract

Groundwater vulnerability assessment shows an extreme sensitivity to in situ anthro-pogenic pollutants. A dichotomous assessment of geological and hydrological (inter alia) characteristics makes it possible to determine the vulnerability of an aquifer. The natural carrying capacity of aquifer can be severely compromised by human activities. The physical structure and material composition of aquifers shows resistance to contaminants transport from surface to water-table. Currently, numerous methods have been posited evaluating aquifer's vulnerability. Similarly the DRASTIC model utilizes computer algorithms and hydro-geological data within a Geographical Information System (GIS) environment to compute aquifer vulnerability.
The degree of vulnerability for each parameter can be evaluated by computing sensitivity analysis of DRASTIC index using GIS, showing the contribution of each parameter to vulnerability sensitivity. The GIS was used to developed map which showed high risk area of 28.8% and moderately vulnerable areas of 46.3% while areas of no risk were 10.4%. Central regions within the study area showed low vulnerability due to dense human settlement and low water level. However, pasture type lands and agricultural areas recorded high risk.
Lahore's environmental and socio-economic development is dependent on policy makers and planner's ability to use information effectively for decision making. The resultant groundwater vulnerability map provides a basis for this aimed at protecting the aquifer from pollutants. Additionally, land use and development activities can be informed by mapping variables, showing that industrial and agriculture areas are highly vulnerable as compare to settlement areas.