DRINKING WATER SUITABILITY OF SANDSTONE AND SCHIST ROCK FORMATION AND DRINKING WATER MANAGEMENT IN LADNU BLOCK OF NAGAUR DISTRICT, RAJASTHAN, INDIA

Water is source of living world. Aridity in the State of Rajasthan including Nagaur district has caused not only scarcity of water resources but also adversely affected quality of precious groundwater assets. In view of acute water crisis, hydrogeological studies were carried out in Ladnu block of Nagaur district for identifying various water related issues and to explore management options thereof. A total of 18 wells were identified as monitoring stations and water samples were collected and analysed for pH, electrical conductivity, total dissolved solids (TDS), total hardness, total alkalinity, fluoride (F-), chlorides (Cl-), and nitrates (NO3-) etc. Fluoride concentrations in surface and groundwater collected from these villages varied between 0.0 and 13.20 mg/l. Groundwater contained high concentrations of fluoride in deep wells as compared to shallow dug wells and pond water, which could be due to occurrence of fluoride bearing minerals (fluorite and fluoroapatite) in sandstone and schist geo-formations in the area. From the data, it is evident that the large population in the study area is severely affected by disease called fluorosis. Dental and skeletal fluorosis and deformation of bones in children as well as adults were observed in the study area owing mainly to excess fluoride concentration in drinking water. The area also witnesses high TDS in sub-surface water. Fluoride concentrations showed good correlation with TDS & EC compared to other chemical parameters like nitrate, total hardness and chloride constituents. The major issues in the block area include less availability of surface water due to low rainfall, high potential evapo-transpiration, occurrence of frequents droughts, deep and declining groundwater levels, depletion of groundwater resources/drying up of potential aquifers due to over-exploitation and also problem of poor quality of groundwater including high salinity and fluoride concentrations. The main management options for addressing various issues include multi-dimensional and multi-spectral options of water conservation especially in irrigation sector (adopting micro-irrigation practices, growing water efficient crops etc.) augmentation of groundwater resources (rainwater harvesting artificial recharge of potential aquifer systems), de-fluoridation/de-salination using non-conventional energy, regulatory measures etc,(Sharma andRojh,2020).