10.4122/1.1000000639
HUANG, GUOBIAO
GUOBIAO
HUANG
guobiao2002@yahoo.com
Yeh, Gour-Tsyh
Gour-Tsyh
Yeh
gyeh@mail.ucf.edu
HUANG, GUOBIAO
GUOBIAO
HUANG
guobiao2002@yahoo.com
An Integrated Media, Integrated Processes Watershed Model – WASH123D: Part 3 –a comparative study on different surface water/groundwater coupling approaches
XVI International Conference on Computational Methods in Water Resources
2006
2006
In the core of an integrated watershed model is the coupling among surface water and
subsurface water flows. Recently, there is a tendency of claiming the fully coupled
approach for surface water and groundwater interactions in the hydrology literature.
One example is the assumption of a gradient type flux equation based on Darcy’s Law
(linkage term) and the numerical solution of all governing equations in a single
global matrix. We argue that this is only a special case of all possible coupling
combinations and if not applied with caution, the non-physical interface parameter
becomes a calibration tool. Generally, there are two cases based on physical
nature of the interface: continuous or discontinuous assumption, when a sediment
layer exists at the interface, the discontinuous assumption may be justified. As for
numerical schemes, there are three cases: time-lagged, iterative and simultaneous
solutions. Since modelers often resort to the simplest, fastest schemes in
practical applications, it is desirable to quantify the potential error and
performance of different coupling schemes. We evaluate these coupling schemes in a
finite element watershed model, WASH123D. Numerical experiments are used to compare
the performance of each coupling approach for different types of surface water and
groundwater interactions. These are in term of surface water and subsurface water
solutions and exchange flux (e.g. infiltration/seepage rate). It is concluded that
different coupling approaches are justified for flow problems of different spatial
and temporal scales and the physical setting of the interface.