Isotope hydrology and geophysical techniques for reviving a part of the drought prone areas of Vidarbha, Maharashtra, India

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A multidisciplinary approach including environmental isotope (δ2H, δ18O and 3H), hydrochemistry and electrical resistivity tools were used to revive a part of the drought prone areas of Vidarbha region, Maharashtra, India. In this study, groundwater recharge processes, monsoon characteristics, climate variables during evaporation in the region were evaluated using environmental isotope techniques. Additionally, electrical resistivity surveys were also conducted to understand the aquifer geometry and weak zones (fractures, lineament) for the sustainable groundwater development. Significant seasonal variation observed in stable isotopic composition, deuterium excess and tritium in precipitation helped to delineate the sources of vapour generating the rains during both the southwest and northeast monsoons. A negative correlation between stable isotopic content and amount of precipitation is observed. Two sources of groundwater recharge, namely, natural recharge from precipitation and contribution from artificial recharge structures (detention tanks) were deduced. Hydrochemical data also corroborates the above findings. Environmental isotope data show that the groundwater is predominantly recharged from the southwest monsoon, and the contribution from the northeast monsoon is insignificant. Tritium data indicate that the groundwater is modern and its residence time is of the order of a few years. Modelling of evaporative isotopic enrichment helped in estimating the climatic variables such as temperature and humidity during evaporation. Also, the recharge from the detention tanks was quantified based on isotope balance model. Aquifer geometry and groundwater potential zones were delineated in a part of the study area using electrical resistivity method. An integrated approach of multidisciplinary techniques is found to be effective in assessing the recharge processes and groundwater potentiality in drought prone areas.