Impact of geology and geomorphology on fluoride contaminated groundwater in hard rock terrain of India using geoinformatics approach

The present study demonstrates a GIS-based spatial evaluation of fluoride contamination (FC) in groundwater vis-a-vis geology and geomorphology of the area using analytical hierarchy process and weighted sum method in Palamu district of Jharkhand. The integration and analyses of the various thematic databases along with the field sampled fluoride data proved useful in delineating the FC zones. The FC index ranged between 141 and 707, and was classified into four zones, viz., low, moderate, high, and very high zones of FC. The FC index map showed that a total of 49.75% of the study area lies between high to very high FC zone. The very high FC zone is found in the moderately weathered plateau with granitic terrain, whereas the high and moderately FC zones covering 49.31 and 36.41% of the study area are dominated by plateau weathered shallow, pediment–inselberg complex, pediplain moderately weathered, pediplain shallow weathered, and inselberg which have high fluoride. The lowest FC zone covers an area of 193.27 sq. km (13.84%). The spatial analysis of geology with fluoride showed that groundwater within granitic gneiss exhibits high FC followed by granitoid gneiss and alluvium. Geomorphologically highest FC was recorded in plateau weathered moderate (91.67%) followed by plateau weathered shallow (71.43%), flood plain (41.76%), inselberg (27.27%), and pediment (25%). The spatial analysis of groundwater yield with fluoride showed that regions having good yield exhibit maximum FC thereby accelerating the vulnerability of the population to fluorosis. © 2017, The Author(s).