Hydrogeological, hydrochemical and isotopic investigations are the main areas of research in order to assess the groundwater recharge, potential zones and its residential time (14C Dating), assessment of groundwater quality/contamination, soil contamination and related mechanisms that are necessary to suggest remedial measures. This research involves both lab and field based work as well as numerical modelling for investigating the controls on the chemical and isotopic composition of water. The focus is to understand the hydrogeochemical and isotopic characterizations of groundwater, soil-water-rock interactions and saline-freshwater interface/interaction in the coastal aquifers from the selected study areas. The variations in the chemistry help to address the environmental problems, few case studies of which are mentioned here. In the proposed township near Rawatbhata, Chittaurgarh district of Rajasthan, the hydrogeological investigations and water quality monitoring in existing bore wells were carried out to indicate the suitability of the site. Identification of fluoride rich groundwater zones and their probable sources using hydrochemical and isotopic tools have been carried out in Nalgonda (Telangana), Prakasam and Anantapur Districts (Andhra Pradesh) and Dwarka basin (West Bengal). An experiment on fluoride mitigation in groundwater through artificial recharge techniques was carried out in a village of Chhindwara district in Madhya Pradesh (India). Assessment of uranium and associated water quality parameters in groundwater used as source of drinking water have been carried out in Hyderabad, Ranga Reddy, Nalgonda and Mahbubnagar districts. Investigations on physicochemical and biogeochemical processes controlling the migration of heavy metals and oil products were performed in the sub-surface environment of Kukatpally watershed, Hyderabad while the chemical speciation and bioavailability of potentially toxic metals have been studied in the soils of contaminated sites at Unnao-Kanpur IDA, (UP) and Patncheru IDA (Hyderabad). To identify the water yielding fracture zones in the bore wells, EC, temperature profiling and depth sampling methods are being employed. In the seismically active Koyna-Warna regions of India, earthquake precursor studies are being carried out using the hydrochemical and isotopic signatures in the groundwater sampled from bore wells (up to a depth of 250 m). It is observed that hydrochemical cycle is closely associated with local earthquakes of M>5 and the increasing concentrations of different ions indirectly indicates the on-going earthquake processes in the region. This activity also involves neotectonics and geodynamical studies encompassing paleoseismological, paleoclimatic investigations, characterisation and mapping of active faults, regional landscape and terrain characterization using the tools like 14C dating of organic materials, optically stimulated luminescence (OSL) dating of sediments and low temperature thermochronological methods in the various geological terrains of the Indian land mass.