Geospatial Analysis of Fluoride Concentration in Groundwater in Puruliya District, West Bengal

Fluoride contamination in groundwater is a major geo-environmental issue. In India, groundwater sources contribute more than 85 per cent of the drinking water requirement in rural areas, 76 per cent of irrigation requirements and more than 50 per cent of the urban and industrial water supplies. Many studies have reported fluoride-related health problems such as dental and skeletal fluorosis in humans due to drinking of fluoride-rich water which has severe socio-economic implications. The permissible limit of fluoride in drinking water is 1.5 mg/l according to the World Health Organisation (WHO, 2004) and the Bureau of Indian Standards (BIS, 2012). Puruliya is the westernmost district of West Bengal and located on the eastern slope of the Chotanagpur plateau. The intensive and prolonged dry spell, semi-arid climate, long-term withdrawal of groundwater for irrigation, alkaline nature of sub-surface circulating water, a long residence time of water in fractured aquifers and low chances of dilution are favourable for fluoride enrichment in the Puruliya District. Eighteen out of 20 blocks of the district have high fluoride level in groundwater. This paper attempts to examine the status of fluoride concentration in groundwater, its distribution including the causative factors for its occurrence. It also tries to draw a comparative view of the change in fluoride pattern for the period 2005-06 and 2015-16 and estimate population under threat. Data collected from Physical Health & Engineering Department (PHED) is superimposed over topographical maps and Google Earth. Mapping of fluoride endemic areas in Puruliya district is attempted to delineate areas and the extent of fluoride contamination in the study area