Application of environmental isotopes in water cycle

Environmental isotope exists extensively in various kinds of water. Every kind of water has the distinct isotope composition because of the isotopic fractionation in the transfer and the circulation among precipitation,surface water,groundwater,soil moisture and plant water. The present status of isotope hydrology is reviewed with the accent on techniques which are most frequently used or the potential perhaps,as yet,not fully utilized. The topics included within the group of environmental isotope techniques are the recharging and the dating of groundwater,the elevation of recharge area,the runoff studies,the interaction of surface water with groundwater and the leakage between aquifers. With regard to the future this paper points out the need for a more quantitative approach to the interpretation and presentation of results.