Isotope hydrology studies on water resources in western Rajasthan

Environmental isotope studies in the Jalore and Barmer areas show that deep groundwaters have depleted 2H and 18O compared to the present day precipitation and have negligible tritium. Radiocarbon levels indicate groundwater ages ranging from 2400 to 7400 BP. Shallow groundwaters, on the other hand, show bomb tritium indicating some component of modern recharge. Studies on the effect of the Indira Gandhi canal on groundwater environment helped in differentiating the areas waterlogged by canal seepage and those affected by return flow of irrigation. A study on the buried channel of the legendary 'Saraswati' river in Jaisalmer district indicates shallow waters are old with 14C content of 54.9 pMC to 58.8 pMC (uncorrected ages: 4950 to 4400 BP) with a velocity of about 20 m/a.