HR: 11:35h
AN: H12B-06    [Abstracts]
TI: Importance of the geosphere-biosphere interface on circulation of groundwater
AU: * Worman, A
EM: anders.worman@bt.slu.se
AF: Prof Anders Worman, Dept of Biometry and Engineering / SLU, Uppsala, 75007 Sweden
AB: This paper describes a hydrological and geochemical modelling approach for assessment of the migration pathways of reactive solutes in a watershed. The study shows that surface topography, stream network characteristics and thickness of quaternary deposits controls the circulation pattern of the deep groundwater. This issue has been found relevant for the safety evaluation of the final repository in bedrock of high-level nuclear waste. Reactive solute transport in a network of stream channels and sub-surface flow pathways is described by convoluting unit solutions based on a physical representation of transport and topographical information of the distributions of solute load as well as pathways. Topographical data and other geographical information are obtained for the mid part of Sweden. A 3D groundwater model is used to derive the residence time distribution of groundwater and the distribution of discharge areas in the watershed. The study shows that a relatively small fraction of the total water budget reaches as deep as 500 m were the Swedish nuclear waste repository is supposed to be placed. The water exchange is controlled by topography on both the continental scale as well as regional scale. The discharge areas are distributed in a relatively small part of the watershed in stream and lake bottoms and to some extent in wetlands. A minor fraction of migrating radionuclides are also taken up by the root system of trees.
DE: 1806 Chemistry of fresh water
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting