HR: 0800h
AN: H51B-0360    [Abstracts]
TI: Isotope-derived water age and composition of streamflow in large river basins
AU: * Koeniger, P
EM: koeniger@uidaho.edu
AF: College of Natural Resources (CNR), University of Idaho, Moscow, ID 83843 United States
AU: Krause, W J
H51B-0360 AF: Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, Koblenz, 56068 Germany
AU: Leibundgut, C
H51B-0360 AF: Institute of Hydrology (IHF), University of Freiburg, Freiburg, 79098 Germany
AU: Maloszewski, P
H51B-0360 AF: National Research Center for Environment and Health (GSF), Ingolstaedter Landstraße 1, Munich, 85764 Germany
AB: Various isotopes can be used to estimate water age in hydrological systems; tritium as well as stable isotopes (deuterium and oxygen-18) have been used. These isotopes are also useful in separating discharge components (e.g., pre-event water, event water) and identifying source areas. These isotopes have often been applied to studies of groundwater and small catchments whereas an interpretation of multiple isotopes in streamflow of larger catchments is rather rare. To decrease costs, investigations using multiple isotopes are usually limited to relatively short time scales. In this study, stable isotopes (deuterium and oxygen-18) were measured monthly over a two-year period in seven sub-catchments of the Weser River, Germany (5,410 km² to 46,240 km², altitudes ranging from 0 to 1100 m asl). The data were analyzed using lumped-parameter (box) models (dispersion model, FLOW-PC). The results were compared to data derived from long-term tritium modelling (>30 years) using the TRIBIL model (tritium balance model, including an exponential approach), assuming similar conditions for input data (GNIP IAEA/WMO network) and storage components (direct flow, fast and slow groundwater). The TRIBIL model leads to mean residence times of total flow between 14 and 50 years due to an estimated amount of 9 to 35% of slow moving groundwater. Using multiple approaches may help reduce uncertainty in defining residence times, model parameters, and storage compositions.
DE: 1800 HYDROLOGY
SC: Hydrology [H]
MN: Fall Meeting 2005