Abstract:
Increasing water demand, zonal disparity in water supply and disproportionate use of groundwater resulted in widespread decline in water table and productivity of wells, increasing pumping cost and energy requirement, and expanding areal extent of groundwater quality degradation. In this context, case studies on advanced radioisotopic (3H, 14C) and stable isotopic (2H, 18O) investigations, conducted in the Indo-Gangetic Alluvial Plains; Sabarmati River Basin and Rajasthan, have been described and technology packages have been suggested.The studies indicate that groundwater recharge from rainfall varies widely from region to region and within the parts of a region, depending on the frequency, intensity and distribution of rainfall, evaporation and landuse, and significant stratification exist at many places. Groundwater contamination is mostly derived from slow infiltration of agricultural and urban surface run-off, through stagnant water pools, alongwith indiscriminately used agrochemicals and land-disposed anthropogenic wastes. The levels of contaminants in groundwater vary spatially and temporally due to different degrees of evaporation/recharge and adsorption/dispersion of contaminant species in the soils. Abstraction induced mixing of highly contaminated groundwater with fresh water takes place along specific flow-pathways.The inherent specificity and complexities of the groundwater system calls for consolidation of existing efforts and reorientation of future research to problem-solving inter-disciplinary approaches, cutting across other areas such as environment, physical sciences, earth and atmospheric sciences, applicable at the local level. Advanced 'packages' and programmes of training in isotopic surveying is very essential for detailing hydrogeologic characteristics of the flow field and pollutants dynamics in the groundwater, under natural and exploited conditions.
