TY - JOUR
T1 - Integrated surface-groundwater flow modeling
T2 - A free-surface overland flow boundary condition in a parallel groundwater flow model
AU - Kollet, Stefan J.
AU - Maxwell, Reed M.
N1 - Funding Information:
This work was conducted under the auspices of the US Department of Energy by the University of California, Lawrence Livermore National Laboratory (LLNL) under contract W-7405-Eng. This work was funded by DOE Fossil Energy Program NETL, NPTO, Tulsa, OK and by the LLNL OPC program. We are especially indebted to S. Panday, for providing the original data of the HEC1-1, HSPF, and MODHMS simulations for Fig. 3 , Joel VanderKwaak, for providing the data of the laboratory experiment by Abdul and Gillham [1] , and Andrew Tompson, for the constructive discussions. We also wish to thank the four anonymous reviewers for adding to the quality of this manuscript. The support with ParFlow by Robert Falgout and Carol Woodward is gratefully acknowledged.
PY - 2006/7
Y1 - 2006/7
N2 - Interactions between surface and groundwater are a key component of the hydrologic budget on the watershed scale. Models that honor these interactions are commonly based on the conductance concept that presumes a distinct interface at the land surface, separating the surface from the subsurface domain. These types of models link the subsurface and surface domains via an exchange flux that depends upon the magnitude and direction of the hydraulic gradient across the interface and a proportionality constant (a measure of the hydraulic connectivity). Because experimental evidence of such a distinct interface is often lacking in field systems, there is a need for a more general coupled modeling approach. A more general coupled model is presented that incorporates a new two-dimensional overland flow simulator into the parallel three-dimensional variably saturated subsurface flow code ParFlow [Ashby SF, Falgout RD. A parallel multigrid preconditioned conjugate gradient algorithm for groundwater flow simulations. Nucl Sci Eng 1996;124(1):145-59; Jones JE, Woodward CS. Newton-Krylov-multigrid solvers for large-scale, highly heterogeneous, variably saturated flow problems. Adv Water Resour 2001;24:763-774]. This new overland flow simulator takes the form of an upper boundary condition and is, thus, fully integrated without relying on the conductance concept. Another important advantage of this approach is the efficient parallelism incorporated into ParFlow, which is exploited by the overland flow simulator. Several verification and simulation examples are presented that focus on the two main processes of runoff production: excess infiltration and saturation. The model is shown to reproduce an analytical solution for overland flow, replicates a laboratory experiment for surface-subsurface flow and compares favorably to other commonly used hydrologic models. The influence of heterogeneity of the shallow subsurface on overland flow is also examined. The results show the propagation of uncertainty due to subsurface heterogeneity to the overland flow predictions and demonstrate the usefulness of our approach. Both the overland flow component and the coupled model are evaluated in a parallel scaling study and show to be efficient.
AB - Interactions between surface and groundwater are a key component of the hydrologic budget on the watershed scale. Models that honor these interactions are commonly based on the conductance concept that presumes a distinct interface at the land surface, separating the surface from the subsurface domain. These types of models link the subsurface and surface domains via an exchange flux that depends upon the magnitude and direction of the hydraulic gradient across the interface and a proportionality constant (a measure of the hydraulic connectivity). Because experimental evidence of such a distinct interface is often lacking in field systems, there is a need for a more general coupled modeling approach. A more general coupled model is presented that incorporates a new two-dimensional overland flow simulator into the parallel three-dimensional variably saturated subsurface flow code ParFlow [Ashby SF, Falgout RD. A parallel multigrid preconditioned conjugate gradient algorithm for groundwater flow simulations. Nucl Sci Eng 1996;124(1):145-59; Jones JE, Woodward CS. Newton-Krylov-multigrid solvers for large-scale, highly heterogeneous, variably saturated flow problems. Adv Water Resour 2001;24:763-774]. This new overland flow simulator takes the form of an upper boundary condition and is, thus, fully integrated without relying on the conductance concept. Another important advantage of this approach is the efficient parallelism incorporated into ParFlow, which is exploited by the overland flow simulator. Several verification and simulation examples are presented that focus on the two main processes of runoff production: excess infiltration and saturation. The model is shown to reproduce an analytical solution for overland flow, replicates a laboratory experiment for surface-subsurface flow and compares favorably to other commonly used hydrologic models. The influence of heterogeneity of the shallow subsurface on overland flow is also examined. The results show the propagation of uncertainty due to subsurface heterogeneity to the overland flow predictions and demonstrate the usefulness of our approach. Both the overland flow component and the coupled model are evaluated in a parallel scaling study and show to be efficient.
KW - Hydrograph uncertainty
KW - Integrated parallel modeling
KW - Overland flow boundary condition
KW - Subsurface heterogeneity
KW - Surface-groundwater interactions
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U2 - 10.1016/j.advwatres.2005.08.006
DO - 10.1016/j.advwatres.2005.08.006
M3 - Article
AN - SCOPUS:33744806403
SN - 0309-1708
VL - 29
SP - 945
EP - 958
JO - Advances in Water Resources
JF - Advances in Water Resources
IS - 7
ER -