EVALUATION OF GROUNDWATER CONTAMINATION RISK FROM PETROLEUM PRODUCTS IN BLANTYRE

The purpose of this study is fill the missing data in Groundwater risk from petroleum products in Blantyre city. Groundwater is a very important source of water and is used for domestic purposes in many areas of Malawi including Blantyre City hence it needs to be taken care of. But due to human activities such as building of filling stations and use of Petroleum products has made groundwater to be vulnerable to contamination.
Using the DRASTIC model, this Paper has a main objective to assess groundwater contamination risk from petroleum products such petrol, Diesel and lubricants which are sold in filling station
within Blantyre city. This research involved the use of secondary data which has been obtained from different sources from internet websites, it is more of desktop work and It used the quantitative and qualitative approach. ArcGIS software has been used in order to come up with parameter maps (D.R.A.S.T.I.C) and data has been retrieved from USGS dataset portal, Africa groundwater website, MASDAP, Literature, Soil Map of Malawi. The seven parameters of this Model include; Depth to water table(D), Net recharge(R), Aquifer Media(A), Soil Media(S), Topography(T), Impact of Vadose(I) and Hydraulic. The fixed weights assigned to the parameters are 5,4,3,2,1,5 and 3 respectively. The data processing involved raster conversion, reclassifying each parameter Map, rating the parameters and using the weighted sum, overlying the parameters and come up with the DRASTIC index and Vulnerability Map. The DRASTIC map produced was classified into very low, low, moderate and high vulnerable zones, and indicated that more areas in Blantyre city falls within very low and low vulnerable zones and in those areas its where a lot of filling stations are belt. The areas where filling stations are more close to each to each the risk to contamination is high because the source of contamination is more e.g. Limbe compared to those areas with filling stations far from each other e.g. along the High way from Chichiri to Clock tower.