[en] Hydrosalinity evolution and interconnections between aquifers is examined in Thiruvanmiyur aquifer situated south of Chennai, Tamil Nadu. Different aquifer systems have been differentiated using environmental tritium, stable isotope (¹⁸O) and hydrological data. Results show that groundwater salinity is due to dissolution of aquifer material and possibility of aquifer interconnections is remote. (author)

[en] Indo-Gangetic -aquifer system provides water supplies to most populous regions of Indian sub-continent, however precise knowledge on the sources and dynamics of groundwater is still missing. Environmental isotopes (²H, ¹⁸O, ¹³C, ³H and ¹⁴C) and hydrochemical modeling tools have been applied in this study to investigate key hydrogeological aspects of the multi-tiered aquifers belonging to Middle Gangetic Plains (MGP)

[en] Water is one of the most important renewable natural resources for supporting life. The availability of potable water has become a major concern to mankind today, as issues related to water affect the lives of many millions of people all over the globe. The growing demand for good quality water for drinking, agricultural and industry has imposed tremendous pressure on the available freshwater reserves. This warrants a careful assessment of the water resources for the sustainable development that can be achieved through extension of the existing techniques and also developing newer scientific tools. Isotope Hydrology is one such newer and potential tool that uses the relative distribution of isotopes of H and O atoms in water molecule to infer processes that are otherwise difficult by conventional techniques. Various natural phenomena leave their signature on the water molecules which can be decoded by measuring the isotopic composition of water samples and the processes the molecules have undergone is then deciphered. This article gives an overview of the basis of application of environmental isotopes in hydrology and future prospects. (author)

[en] Environmental isotopes (stable and radioactive) have been used as tracers for investigating various hydrological problems. Wide variation in isotopic distribution (²H, ¹³C, ¹⁸O, ¹⁵N, ³⁵S, ³H and ¹⁴C) in the environment help in identifying the source, origin, pathways and processes affecting the system under consideration. In this article, a few Indian case studies covering some of the very important isotope applications in groundwater hydrology are briefly summarized. (author)

[en] Environmental isotope techniques have been used to study various hydrological processes like determining the source and movements of water and solutes, assessing water budget and geochemical models, investigating dynamics of groundwater flow and measurement of aquifer parameters. An isotope hydrochemical investigation was carried out to understand the fly ash movement in the groundwaters near Anpara Thermal Power Plant in Uttar Pradesh, on request from the Uttar Pradesh Rajya Viydut Utpadhan Nigam Limited (UPRVUNL) authorities

[en] Identification of source and origin of groundwater and recharge chronology is of great importance for systematic planning for groundwater development and management, to sustain the current and future levels of the human development. Environmental tracers have been established as potential tools in tracing groundwater and its interconnections with other water bodies. Environmental isotopes are used as a modern, specific and reliable technique in understanding various hydrological processes. This study pertains to central region of Telangana, which falls under semi-arid region (∼ 900mm total rainfall) and most of the rainfall is mostly confined to a few intense rain events, storage and proper utilization of this vital source is very important. Tanks play a major useful role in confining the surface run-off and enhancing the groundwater recharge in shallow zones. This paper highlights the findings obtained from an isotope investigation to evaluate tank contribution to local groundwaters

[en] Uranium is a weakly radioactive heavy metal having three natural isotopes namely; ²³⁴U (0.0054%), ²³⁵U (0.72%) and ²³⁸U (99.27% wt.). It causes both chemotoxicity as well as radiotoxicity, though the impact of chemotoxicity is greater as compared to its radiotoxicity. It is reported that uranium has the tendency to accumulate in kidneys, liver and bones of human. World Health Organization (WHO) and U.S. Environmental Protection Agency (US EPA) have set a guideline value of U at 30 µg/L in drinking water, while considering the radiotoxicity, AERB (India) has set a regulatory limit of 60 µg/L in drinking water. The present study reports of the occurrence and discusses the distribution of dissolved uranium in intermontane basin of Imphal where groundwater is widely used for drinking and irrigation. The study area is an alluvium of fluviolacustrine origin belonging to Quaternary age. This study provides a baseline data for U in groundwaters of Imphal valley and further research is being carried out to evaluate other toxic metals as well as geochemical processes controlling water quality in the region

[en] To investigate the possible source of contamination in groundwater at IRE site and its movement in the subsurface, water samples collected from peizometers, hand pumps, storm water drains, Periyar river and various effluent discharge points in and around the IRE campus were analysed for major ion chemistry and environmental isotopes (δ²H, δ¹⁸O)

[en] Proper understanding of the impact of paleochannel network on groundwater recharge can help in planning effective measures for groundwater replenishment. Paleochannels are old/buried sand deposits which can act as good conduits for rainwater infiltration. Considering the growing concerns on groundwater level depletion in Central Ganga Basin, an isotope investigation was carried out in Prayagraj, Uttar Pradesh to assess groundwater dynamics along suspected paleochannels. A total of 14 samples were collected for radiocarbon measurements from tube wells tapping different depths. In the field, the dissolved inorganic carbon (DIC)is collected from about 60 L of water by precipitating in the form of barium carbonate. In the laboratory, the precipitates were treated with phosphoric acid under vacuum to release carbon dioxide, which is absorbed in carbasorb scinitallator mixture and counted in liquid scintillation system for 1000 minutes

[en] In India, recharge varies due to different types of soils, wide geographical variations, amount of rainfall and under different climatic conditions. It ranges from 4 to 20%. Estimation of natural recharge or return flow of irrigation by tagging a tracer below the root zone is well-established and commonly used method. In this method a suitable tracer is tagged and its displacement is measured after regular time intervals (after rainy season or irrigation events). The percentage recharge is estimated to be 14 % from injected tracers for total 550mm rainfall (including five irrigation events). The recharge estimated from δ¹⁸Q and excess fertilizer nitrate tracers was 10% without contribution from irrigation events