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The Use of Environmental Isotopes to Assess Sustainability of Intensively Exploited Aquifer Systems
Closed for proposals
Project Type
Project Code
F33019CRP
1887Approved Date
Status
Start Date
Expected End Date
Completed Date
22 March 2016Description
Intensive exploitation of groundwater over decades has led, in many important aquifers, to marked lowering of water tables, increasing exploitation costs, and often, to a progressive deterioration of water quality. These effects are the result of overexploitation, changing flow patterns in the aquifers due to concentrated pumping or lack of physical protection to prevent the migration of pollutants into aquifers. Isotope hydrology tools have proven to be very useful in assessing groundwater hydrology, addressing aspects related to recharge processes, delineation of flow patterns, water quality issues and interactions with other water bodies; this unique information can be used to evaluate long term aquifer sustainability. The objective of this Coordinated Research Project (CRP) is to develop and review approaches and methodologies, mostly based on the combined use of conventional hydrogeological techniques and environmental isotopes, to assess the response of groundwater systems to intensive exploitation and groundwater availability. Access to new dating tools and approaches for groundwater dating covering different time scales offers the possibility to evaluate changes in groundwater dynamics and flow patterns, providing key data to predict the evolution of aquifers and their sustainability as major sources of water. The CRP aims to assess the performance of these new tools and approaches and the possible adoption of these methods by water management experts.
Objectives
To improve capability and expertise among Member States in the use environmental isotopes and other geochemical tracers to better assess the sustainability of intensively exploited aquifers.
Specific objectives
Assessment of the potential and limitations of new isotope and geochemical methodologies for routine application in hydrological studies.
Development of thematic maps based on isotope and related data of hydrological variables relevant to the evaluation and assessment of water resources in areas under intensive exploitation.
Development/review of the combined used of common and recently developed approaches for dating groundwater aimed at assessing the sustainability of selected intensively exploited aquifers.
Impact
Despite the problems listed above, the CRP has been completed successfully by most Member States. This CRP clearly revealed that the use of environmental isotopes such as stable isotopes (oxygen-18 and hydrogen-2), tritium and carbon-14 can be used as an early warning indicators and tracer calibrated flow models can be used as a management tools for intensively exploited aquifers. However, the impact of this CRP will be observed later, when the participating institutions/organisations, with the help of the Agency (through its TC Department), will disseminate this experience to the managers and users of groundwater in their Member States and help them, particularly in the developing countries, to get the isotopic measurements done and 3D calibrated models are developed. It has been found that national agencies, responsible for managing groundwater supply from different important aquifers in developed Member States, routinely measures isotopic compositions and also use tracer calibrated 3D models for managing sustainability of aquifers.
Relevance
Normally, the observed drawdown in the water table is considered as a direct indicator of intensive exploitation of aquifer, but this single parameter does not provide the required information to assess the sustainability of intensively exploited aquifers, as well as the impact of exploitation if the current trends are continued. Environmental isotopes can provide additional key information that can be used to understand the recharge conditions, changes in residence time and the interaction of aquifer with adjoining water bodies. This information may be proved to be very useful in understanding sustainability and impact issues. The change in isotopic composition or residence time is a clear indication that recharge conditions have changed and/or the aquifer is hydraulically connected with adjoining water bodies. This CRP has proved that environmental isotopes should be used in such a cases, although the information may be site specific as the changes in isotopic compositions have been found to be different in different hydrogeological conditions as well as in different aquifers (shallow and deep aquifers, karst vs porous-media aquifers, etc.). Therefore, this CRP has been highly relevant to consider by hydrogeologists certain isotopes as additional tools to be used as indicators of intensive exploitation and impact assessment as well as to use tracer calibrated 3D flow/transport models for the overall management of intensively exploited aquifers. This CRP falls under the Agency's sub program 2.3.3: Radioisotopes applications in hydrology and project 2.3.3.01:Characterisation of fossil groundwater using long-lived radioisotopes.