Simulating complex flow and transport dynamics in an integrated surfacesubsurface modeling framework

Edward A. Sudicky,Jon P. Jones,Young-Jin Park,Andrea E. Brookfield,Dennis Colautti 한국지질과학협의회 2008 Geosciences Journal Vol.12 No.2

A fully-integrated surface-subsurface flow and transport model is applied to a 17 km2 subcatchment of the Laurel Creek Watershed within the Grand River basin in Southern Ontario, Canada. Through past and ongoing field studies, the subcatchment is reasonably well characterized and is being monitored on an ongoing basis. In addition to diverse land-usage and surface cover and more than 65 m of topographic relief, the watershed is underlain by a complex interconnected sequence of sand and gravel aquifers that are separated by discontinuous clayey aquitards. A steady-state condition was achieved in the model by calibrating the subsurface flow field to 16 observation wells where long-term hydraulic head data were available, while simultaneously establishing a level of baseflow discharge on the surface regime approximating the level observed at the beginning of the transient simulation period. The model is then subjected to several hundred hours of rainfall data and the resulting discharge hydrographs are compared with the measured hydrographs. The calculated subsurface hydraulic head distribution and surficial rainfallrunoff responses, respectively, were shown to agree moderately well with those observed in the system during this period. The impact of an upland surficial contaminant source discharging along a reach of a small stream within the subcatchment was also examined. Results showed that short-duration, high-intensity concentration peaks were not captured if annual or monthly average rainfall was used as input. The hydraulic head and concentration variations due to short-duration rainfall variations showed a muted response with increasing depth below the streambed due to the natural smoothing in the hydraulic response and to dispersion and diffusion of the solute, respectively. Discrete daily precipitation events were also found to cause rapid changes in the calculated water and solute exchange fluxes. The variability and sensitivity of these near-stream processes to the temporal resolution of rainfall input, specifically the concentration and solute exchange flux responses, may be significant in the prediction of health risks to aquatic habitats. Overall, it is concluded that the model is capable of reproducing surface and subsurface hydrodynamic processes at the subcatchment scale although the results could be better through improved parameterization of the subcatchment and the manner in which the model simulates evapotranspiration processes. A fully-integrated surface-subsurface flow and transport model is applied to a 17 km2 subcatchment of the Laurel Creek Watershed within the Grand River basin in Southern Ontario, Canada. Through past and ongoing field studies, the subcatchment is reasonably well characterized and is being monitored on an ongoing basis. In addition to diverse land-usage and surface cover and more than 65 m of topographic relief, the watershed is underlain by a complex interconnected sequence of sand and gravel aquifers that are separated by discontinuous clayey aquitards. A steady-state condition was achieved in the model by calibrating the subsurface flow field to 16 observation wells where long-term hydraulic head data were available, while simultaneously establishing a level of baseflow discharge on the surface regime approximating the level observed at the beginning of the transient simulation period. The model is then subjected to several hundred hours of rainfall data and the resulting discharge hydrographs are compared with the measured hydrographs. The calculated subsurface hydraulic head distribution and surficial rainfallrunoff responses, respectively, were shown to agree moderately well with those observed in the system during this period. The impact of an upland surficial contaminant source discharging along a reach of a small stream within the subcatchment was also examined. Results showed that short-duration, high-intensity concentration peaks were not captured if annual or monthly average rainfall was used as input. The hydraulic head and concentration variations due to short-duration rainfall variations showed a muted response with increasing depth below the streambed due to the natural smoothing in the hydraulic response and to dispersion and diffusion of the solute, respectively. Discrete daily precipitation events were also found to cause rapid changes in the calculated water and solute exchange fluxes. The variability and sensitivity of these near-stream processes to the temporal resolution of rainfall input, specifically the concentration and solute exchange flux responses, may be significant in the prediction of health risks to aquatic habitats. Overall, it is concluded that the model is capable of reproducing surface and subsurface hydrodynamic processes at the subcatchment scale although the results could be better through improved parameterization of the subcatchment and the manner in which the model simulates evapotranspiration processes.

Thermal transport modelling in a fully integrated surface/subsurface framework

Brookfield, A. E.,Sudicky, E. A.,Park, Y.-J.,Conant Jr., B. John Wiley Sons, Ltd. 2009 Hydrological processes Vol.23 No.15

<P>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 water flow and heat and solute transport in the 3D subsurface under variably saturated conditions. In this work, the new thermal capabilities of HydroGeoSphere are tested and verified by comparing HydroGeoSphere simulation results to those from a previous subsurface thermal groundwater injection study and also by simulating an example of atmospheric thermal energy exchange. High-resolution 3D numerical simulations of a well-characterized reach of the Pine River in Ontario, Canada are also presented to demonstrate thermal energy transport in an atmosphere–groundwater–surface water system. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the riverbed, the surface water and the groundwater. The computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain a healthy ecosystem. Copyright © 2009 John Wiley & Sons, Ltd.</P>

Kirchhoff Transformation Approach for Simulating Steady-State Variably Saturated Groundwater Flow

Ji Sung-Hoon,Park Young-Jin,Sudicky Edward A.,Sykes Jon F. 대한지질학회 2007 대한지질학회 학술대회 Vol.2007 No.

Application of Kirehhoff Transformation Algorithm to Simulating the Groundwater Flow System at Yucea Mountain

S. H. Ji,Y. K. Koh,Y. Jl Park,E.A. Sudicky 한국방사성폐기물학회 2008 한국방사성폐기물학회 학술논문요약집 Vol.6 No.2