Excessive fluoride in groundwaters of River Sindhanur catchment, South India: a case study from a hard-rock sub-basin with contrasting features

摘要

The catchment of River Sindhanur is a multi-lithic, hard rock terrain located in Raichur and Koppal districts of Karnataka. Metavolcanics and granitic rocks form the major aquifers of the study area, the latter being the major aquifer of India (Sreedevi et al., 2006). The area is arid and frequently affected by drought. The eastern part of the study area is heavily irrigated, whereas the western part is rain fed. Groundwaters from the granitic and irrigated area are characterized by excessive fluoride (Table 1) and >55% of the area is affected by fluoride hazard, including many areas with metavolcanics, which may be attributed to inter-basin groundwater migration and/or to anthropogenic sources.