Analysis of Factors Affecting the Spatio-Temporal Patterns of Thermal Exchange Fluxes between Streams and Groundwater

Eingeladen durch Hydrologie (Dr. Fleckenstein.

E.A. Sudicky, A. E. Brookfield and Y.-J. Park
Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, CANADA, N2L 3G1

Thermal stream loadings from both natural and anthropogenic sources have significant relevance with respect to ecosystem health and water resources management, particularly in the context of future climate change. In recent years, there has been an increase in field-based research directed towards characterizing thermal energy transport exchange processes that occur at the surface water/groundwater interface of streams. In spite of this effort, relatively little work has been performed to simulate these exchanges and elucidate their roles in mediating surface water temperatures and to simultaneously take into account all the pertinent hydrological, meteorological and surface/variably-saturated subsurface processes.
To address this issue, HydroGeoSphere, a fully-integrated surface/subsurface flow and transport model, was enhanced to include fully-integrated thermal energy transport. HydroGeoSphere can simulate water flow, evapotranspiration, and advective-dispersive heat and solute transport over the 2D land surface and in the 3D subsurface under variably-saturated conditions. The new thermal capabilities of HydroGeoSphere were tested and verified by comparing HydroGeoSphere simulation results to those from a well-characterized reach of the Pine River in Ontario, Canada. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the river bed, the surface water and the groundwater.
In this paper, we will use the integrated system modelling framework to explore the physical, geomorphological and climatic factors controlling the spatial and temporal patterns of the thermal energy exchange fluxes between the stream and the underlying groundwater system. The computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain conditions for a healthy ecosystem.

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