ABSTRACT
How is the meteoric 180 - 2H signal transferred to groundwater during recharge? For many groundwaters, their isotopic composition will equal the mean weighted annual composition of precipitation. For others, important deviations from precipitation are found. This transfer function must be understood for groundwater provenance studies. It also sheds light on the mechanisms of recharge. Between the surface and the water table, infiltration must traverse the enigmatic “recharge environment” where groundwater infiltration is complicated by differing types of soils and vegetation, non-saturated flow through heterogeneities porosity, losses to evaporation and transpiration, seasonal variations in recharge, not to mention inter-annual and long-term changes in climate. The residence time within the recharge environment can vary from days to years.
