|
GIS based correlation between groundwater quality parameters and geological units
Database Creation and Methodology The study area boundary, villages, rivers and streams along with ponds, were digitized using the SOI Toposheet 46 E. The drainage pattern and digitized geological map of the study area were obtained. The contour maps of groundwater quality parameter fluoride, calcium, bicarbonates and pH were imported into the GIS and Digital Image Processing software (ILWIS) for georeferencing. The contour interpolation for each groundwater quality parameter was carried out and was rasterized to prepare the spatial variation map. A segment geological map of the study area was also polygonised and then rasterized. Each rasterized groundwater quality parameter map was crossed with the rasterized geological map using the CROSS operation in ILWIS. The CROSS-operation will essentially help in getting the concentration and areal geological unit information. Thus GIS based correlation can be found by knowing the concentration of the parameter of interest and the areal extent of geological unit under it. Results 
The drainage pattern in the study area is shown in Fig. 1. 
The digitised geological map of the study area is shown in Fig.2. 
The bedrock as delineated in the study area chiefly comprises of ultrabasic rocks, gneiss, schists, quartize and quartz-schists. The groundwater quality parameters considered are namely fluoride, calcium, bicarbonate and pH. The spatial distribution maps for the groundwater quality parameters namely calcium, fluoride, bicarbonate and pH are shown in Fig 3-6. 
|