HR: 08:25h
AN: CG21B-02    [Abstracts]
TI: General Trends of Groundwater Renewal in North America and Scandinavia
AU: * Marklund, L
EM: larsmark@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 100 44, Sweden
AU: Worman, A
EM: worman@kth.se
AF: The Royal Institute of Technology, Teknikringen 76, Stockholm, 100 44, Sweden
AB: Depletion of groundwater resources is a pressing problem for large parts of the world's population and has significant ecological impact. Increased water demand due to energy production, population growth, and changes in the water supply due to climate change is increasing the importance of methods for understanding groundwater circulation and renewal. Even if it is well known that topography and geology are key factors controlling groundwater circulation, we have a surprisingly limited quantitative understanding of this control. In humid regions with low permeable rock, where the groundwater surface is a replica of the topography, differences in hydraulic potential created by topography are the main driving force for groundwater flow. In these regions the topography can be used to predict the renewal rate and circulation of groundwater. This is especially useful in data sparse areas or if the aerial extension of the study is large. Here we make use of spectral analysis to relate saturated groundwater flow to landscape topography over all scales of the continental shield. Based on extensive data from Scandinavia and North America, reflecting the topography of landscapes, the bedrock, and the presence of Quaternary deposits, we have found that general trends in the topography creates universal patterns in the groundwater flow. Our results imply that the amount of accessible groundwater decreases fast with depth and at 99.9% of all groundwater circulation occurs at depths less than 700 m. Furthermore, about 90% of the groundwater circulation occurs in Quaternary deposits, even in comparatively thin soil layers like in Scandinavia and parts of North America. The theoretical explanation and the new understanding of the rapidly decaying renewal rate of groundwater with depth are of great importance for water resource management. Our results give an indication of sustainable extraction rates at various depths in the subsurface. The method presented here also enhances our ability to relate changes in surface water levels with increased groundwater withdrawal at a wide range of temporal and spatial scales.
DE: 1829 Groundwater hydrology
DE: 1847 Modeling
DE: 1880 Water management (6334)
DE: 3255 Spectral analysis (3205, 3280)
SC: Canadian Geophysical Union [CG]
MN: 2009 Joint Assembly