Volume 9 Issue 1

Authors: Patrice Jean Jourda; Jean Kan Kouame; Kouakou Serge Deh; Germain Miessan Adja; Jacques Edoukou Djemin

Abstract: The drinking water supply to the population of Dabou area is mainly based on groundwater which also represents an important reserve for the populations of the surrounding regions. However, groundwater resources are exposed to urban and agricultural pollution because of socio-economic or agricultural activities that have multiplied considerably. The present study aims to develop the vulnerability map defined for municipal and industrial pollutants and that defined for agricultural pollutants. Thus, from a GIS, the two versions of DRASTIC model (Standard and Pesticide) were optimized in two ways from the effective weights (Absolute and Relative) following the single-parameter sensitivity analysis to correct the subjectivity linked to the theoretical weights. The results revealed that Standard and Pesticide DRASTIC groundwater vulnerability maps modified from the relative effective weights are the most refined and therefore the most reliable in assessing groundwater vulnerability in this area. Modified vulnerability indices range from 95.97 to 187.42 for modified relative Standard DRASTIC groundwater vulnerability map. This map is divided into very high and high vulnerability classes (covering an area of 1961.27km2 or 80.52%), and moderate and low classes (covering only an area of 474.49km2 or 19.48%). Modified vulnerability indices range from 117.26 to 216.20 for modified relative Pesticide DRASTIC groundwater vulnerability map with very high and high classes covering an area of 2048.72km2 (84.11%) against 387.04km2 (15.89%) for moderate vulnerability class only represented in the North. Groundwater vulnerability to pollution is related to the nature of soils and formations in unsaturated zone of aquifers that are conducive to the transfer of pollutants. Modified relative Standard and Pesticide DRASTIC groundwater vulnerability maps are now innovative decision-making tools to preserve groundwater quality in land-use planning in this area.

Keywords: Groundwater Pollution; Vulnerability; DRASTIC; Sensitivity Analysis; Dabou Area