HR: 10:35h
AN: U52A-02    [Abstracts]
TI: Fractal scaling for surface water-subsurface water interaction through the Earths crust
AU: * Wörman, A
EM: worman@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 10044, Sweden
AU: Marklund, L
EM: larsmark@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 10044, Sweden
AU: Packman, A I
EM: a-packman@northwestern.edu
AF: Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208-3109, United States
AU: Harvey, J W
EM: jwharvey@usgs.gov
AF: U.S. Geological Survey, 430 National Center, Reston, VA, 20192, United States
AU: Stonedahl, S H
EM: susacat@gmail.com
AF: Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208-3109, United States
AB: Landscape topography from mountain ranges to the smallest hills induces the pressure boundary condition at ground surface that controls groundwater circulation. This interplay between surface water and groundwater controls the circulation patterns of deep groundwater in the Earth's crust, the water balance in watersheds, as well as solute transport from the continents to the oceans. Separating the topography in a Fourier spectrum both represents the fractal ground surface topography in fluvial and glacial landscapes and provides an exact solution for the three-dimensional groundwater flows including the surface water interaction. In boreal landscapes where the groundwater surface follows the topography, all landscape features have a significant impact on the surface–subsurface water interaction. However, because of the decaying permeability with depth there is a clear tendency that the interfacial flux tends to be dominated by small-scale features, while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. In the order of 10 % of the precipitation in Scandinavia infiltrates the ground, but only about 1 ‰ of the groundwater recharge reaches deeper than 400 m. The fractal nature of surface-subsurface water fluxes yields a scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. This holds for small- scale exchange occurring in the stream-beds and the deeper circulation of the Earths crust. The fact that we can now estimate the renewal rate of deep groundwater based on a spectral representation of topography over the entire continent has far-reaching implications for the long-term management of groundwater resources. The improved understanding of the exchange processes in the hyporheic zone and its interaction with biogeochemistry and colloids is of utmost importance for understanding recent environmental problems like eutrophication from nitrogen and phosphorus and spreading of toxic substances like heavy metals.
UR: http://www.lwr.kth.se
DE: 0495 Water/energy interactions (1878)
DE: 1622 Earth system modeling (1225)
DE: 1816 Estimation and forecasting
DE: 1829 Groundwater hydrology
DE: 1839 Hydrologic scaling
SC: Union [U]
MN: 2007 Fall Meeting