Getting the Word Out at the EGU

Full text: The Water Resources Programme transferred information about the science of isotope hydrology and ongoing projects of the Isotope Hydrology Section at the 2010 European Geosciences Union (EGU), held at the Austria Center from 3-7 May. A full house was on hand for a presentation made by Section Head Pradeep Aggarwal, who lectured on 'Better Characterization of Young and Old Groundwater Systems Through Improved Groundwater Dating by Isotope Methods', during which he discussed the benefits of proper groundwater dating while highlighting the risks of not defining this resource. Over-extraction can lead to decreased baseflow in rivers, destruction of wetlands, a reduction in water quality, and marked lowering of the water table. A clear understanding of hydrological conditions is necessary to ensure rational management and sustainable withdrawal of these resources. The presentation included information about what types of isotopes are used by the IAEA in the dating of groundwater, including the tritium-helium-3 dating technique for recently recharged groundwater, and radioactive tracers such as carbon-14, chlorine-36 and krypton-81 for groundwater with a longer residence time. A presentation entitled 'Examination of Global River Systems Using Stable Isotope Methods' and delivered by Brent Newman of the Isotope Hydrology Section, was also well attended. The subject of the presentation was the Global Network of Isotopes in Rivers (GNIR), a recent compilation of stable isotope data from rivers around the world; this compilation now makes an initial global comparison of river isotope data feasible. The information available in GNIR shows definite trends, such as latitude effects and strong links between river waters and precipitation. The great variation in captured data reflects the large differences in global climate conditions. A theme currently being examined by the Section is how river isotope distributions can be used to understand a given river's relationship to precipitation inputs and/or degree of processing within a basin. Figures from selected rivers were used to show the effects of seasonality and changes affected in course flow by manmade constructions, such as dams or reservoirs. Many attendees of the conference came to see the Section's poster presentation entitled 'Long-term Tritium Monitoring to Study River Basin Dynamics: Case of the Danube River Basin', and ask questions about the information. The poster described how the IAEA has recently started compiling new and archival isotope data measured in groundwater, rivers, lakes and other water bodies as part of its web based application Water Isotope System for Data Analysis, Visualization and Electronic Retrieval (WISER). WISER is being used to process GNIR information, making detailed river studies possible. Residence time estimates for the Danube in central Europe were re-examined in the highlighted study. Most of the 15 monitoring sites along the Danube have been continuously collecting tritium records for over 10 years, with the longest running and most complete record set coming from Vienna and running back to the 1960s. The IAEA is currently re-evaluating upper Danube residence time using a complete record covering the entire tritium transient created by atmospheric nuclear weapons testing (1964-2005). Models assume that there is a 'fast' component, representing water with a short residence time, and a 'slow' component, representing discharge of older groundwaters to the river. Preliminary results were presented, showing new insights into the age distribution of water in the upper Danube, and initial calculations from the Vienna records, which suggest that mean residence time is much greater than previously thought. The Water Resources Programme disseminated information about the latest developments in isotope hydrology at a booth which displayed posters - including one on recent work undertaken at the Nubian Sandstone Aquifer - along with atlases of isotope hydrology, part of a series being published by the IAEA. Visitors were very interested in material made available by the section at its stand, including CDs, DVDs, postcards, bookmarks, newsletters, pamphlets and books. The EGU - the second largest association of geoscientists - provides an opportunity for specialists and students from around the world to exchange information and find out about the latest developments in their fields at its annual General Assembly. The 2010 gathering was considered to be a great success, with 4431 oral and 9370 poster presentations in 594 sessions. There were 10 463 scientists from 94 countries participating, about a quarter of which were students. (author)