Application of Isotopes in Studying Lake Water – Groundwater Interactions in Parts of Tumkur District of Karnataka

In the present study, to demonstrate use of combined isotopic and salinity mapping in understanding local scale groundwater-surface water conditions the water samples were collected from 4 nos. of defined lakes (Kadaba, Belavatta, Pura and Nittur); groundwater samples were collected from shallow hand pumps/tube wells along the periphery of the lakes. The rain samples were also collected. The lake water appears to get enriched in its isotopic composition mainly due to evaporation in this region. Lake water salinities are lower compared to nearby groundwater salinity. The flow of groundwater, recharged at Nittur lake, continues to its downstream at least till Pura. Increase in salinity of groundwater is seen between the points Pura-groundwater & surface water (may be due to dissolution of sub-surface soil). The groundwater sampled at Belavatta is found to be recharged from local precipitation and not from surface body. The water body (Kadaba) is getting filled mainly due to precipitation and to some extent due to runoff from the upper reach of water body. There is a strong link between lake water–groundwater (e.g. site Pura) and groundwater–lake water (e.g. Site Kadaba). Therefore, this procedure is expected to radically increase the accountability of usage and help in planning of suitable ground water supply and would provide a holistic approach to promote maximum agricultural output and industrial growth.