A GIS ANALYSIS TO MITIGATE THE INCIDENCE OF FLUOROSIS IN DHARMAPURI DISTRICT OF TAMILNADU, INDIA

Fluorosis, which affects our teeth and bones, is caused by the intake of excess fluoride. There are various ways of getting exposed to fluoride. Fluoride bearing bedrocks and fluoride contaminated water occurs in most parts of the world. In India, 18 of the 33 constituent states of the country are affected by fluorosis. Tamilnadu is a southern state having 10 of its 29 districts affected with fluorosis. Dharmapuri district in the north-western part of Tamilnadu, is the most afflicted one.

This project examines the factors that influence the occurrence of anomalous fluoride in groundwater, and analyses the spatial distribution of fluoride in Dharmapuri district using Geographic Information System (GIS). The aim is to use GIS to study the relationship between the distribution of fluorosis and the distribution of fluoride in groundwater. The factors considered in this study include geology (the rocktypes), soil, annual rainfall and landuse. These factors were then incorporated into a GIS environment and a weighted overlay analysis was done to result in a GIS based zonation map.

This map indicates that groundwater in the south-eastern region of Dharmapuri district contains anomalous concentrations of fluoride. Further interpolation with the population distribution map indicates that people in the blocks of Harur, Morappur and Pappireddipatti are most vulnerable, while people in Pennagaram, Nallampalli, Palacode, Karimangalam and Dharmapuri blocks are moderately vulnerable to fluorosis. Suitable rehabilitation measures based on spatial distribution/proximity to fluoride-free surface water resource have also been suggested.