USING GROUNDWATER AGE AND OTHER ISOTOPE SIGNATURES FOR LARGE-SCALE ASSESSMENTS OF GROUNDWATER RESOURCES

Although groundwater provides more than half of the world’s freshwater supply, comprehensive aquifer assessments remain to accomplished in many parts of the world. A lack of these assessments prevents a fuller use of the available water resources and their sustainable management. A lack of assessments also is an impediment to meeting some of the internationally agreed upon goals related to groundwater, such as stopping the unsustainable exploitation of groundwater. Aquifer assessments at regional or national scales can be conducted more effectively and rapidly by using groundwater isotope signatures and ages, which at times may be the only means of building a conceptual hydrogeological framework. Fossil groundwater sustains current food production by irrigated agriculture and also contributes to baseflow of many rivers. It may also be a more important component of river flow under changing climatic conditions. A number of fundamental aspects of aquifer hydrogeology, including recharge, groundwater-surface water interactions, and the extent and distribution of fossil groundwater remain poorly characterized. In this presentation, we will discuss results from Bangladesh, northern Africa, Tanzania and Latin America to demonstrate the role and value of integrating isotopic data with other pieces of information. We will also discuss a recent IAEA initiative to increase the availability and sustainability of groundwater resources through comprehensive, national assessments of water resources. In this initiative, the IAEA, working in partnership with other agencies and entities, aims to assist its member countries in a broader application of tritium-helium, carbon-14 and krypton-81 for groundwater dating. A significant feature of this project is to build national capacity to identify and fill gaps in hydrogeological knowledge.