Water quality index over the decades in Krishnagiri district by using GIS

Abstract

Groundwater is an important source for drinking water especially in rural areas. The lack of clean drinking water is advising affecting the general health and life expectance of the people in many developing countries. India with declining fresh water resources has an acute shortage of potable water of acceptable quality. In Krishnagiri Groundwater from phreatic aquifers is colorless, odorless and predominantly alkaline in nature. Water quality data of 82 observation wells for 38 years (1975 to 2013) was collected from the office of State Surface & Ground Water Data Centre, Public Works Department, Taramani, Chennai, Tamil Nadu and analyzed. Based on these data, the hydrological parameters of the study area was estimated and water quality index map was prepared to assess the suitability of drinking water. It is observed that the ground water is suitable for drinking and domestic uses in respect of all the constituents except total hardness, fluoride and nitrate in about 67.85 and 50% of the samples. Total hardness as CaCO3 is observed to be in excess of permissible limits in 33% of the samples analyzed, whereas nitrate is found in excess of 45 mg/l in about 50% of samples. Excess fluoride more than the permissible limit of 1.5 mg/l is observed at K.Vetrapatti and Karukanchavadi areas. The incidence of high total hardness is attributed to the composition of litho-units constituting the aquifers in the district, whereas nitrate pollution is most likely due to the use of fertilizers and other improper waste disposal.