38. Assessment of Groundwater Recharge due to Monsoon in Ozar Watershed of Maharashtra State Using Isotopic Technique

The over exploitation of groundwater in India is increasing day by day due to ever increasing population and industrialization, resulting in progressive lowering of static water level and reduction of well yields. The estimation of recharge to groundwater is crucial to better water resources management particularly in arid and semi-arid regions. The tritium tagging technique has been widely used for the estimation of groundwater recharge in different regions of India. This technique provides fairly accurate estimate of vertical downward flow component of soil moisture through unsaturated zone. In the present paper, the groundwater recharge due to monsoon rains in Ozar watershed located in Nashik district (Maharashtra) in Godavari basin has been assessed using tritium tagging technique. The experiments have been carried out in cultivated agricultural fields. Artificial radioisotope (Tritium) was injected at four cultivated sites before the onset of monsoon and soil samples were collected from the injection points soon after the withdrawal of monsoon. In the study area, mainly three types of soils were found, namely clay, loam and sand in which sand predominants. The percentage of groundwater recharge varies from 9.77 % to 23.19 % in the study area depending on the type of soil and other geo-hydrological conditions of the study area.