HR: 0830h
AN: H11G-0945    [PDF]
TI: Comparison of Three-Dimensional Local Grid Refinement Methods For Simulating Stream-Aquifer Interactions
AU: * Mehl, S
EM: swmehl@usgs.gov
AF: U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303-1066 United States
AU: Hill, M C
EM: mchill@usgs.gov
AF: U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303-1066 United States
AB: Many groundwater models require a fine grid discretization in limited areas of interest. One way of achieving greater grid resolution in a limited area of the domain is to use a method of local grid refinement. Unfortunately, accurate, fully three-dimensional local grid refinement methods are weak or unavailable in commonly used block-centered finite-difference models of groundwater flow. This work extends the previously developed two-dimensional, iterative shared-node local grid-refinement method of Mehl and Hill (2002) to three dimensions. To interpolate head boundary conditions onto the interface of the three-dimensional local grid, a new numerical interpolation technique was developed that retains the physics of the regional-grid flow. The iterative solution method adjusts the heads and fluxes of both grids to achieve equilibrium. This introduces some error into the final solution, however these errors are less than if no iterations are performed, as in a one-way coupled telescopic mesh refinement (TMR) approach. Three-dimensional, locally refined simulations of stream-aquifer interactions using the iterative shared-node method resulted in errors in stream flux less than 2%, while commonly used one-way coupled TMR resulted in errors in stream flux greater than 10%.
DE: 1829 Groundwater hydrology
SC: Hydrology [H]
MN: 2003 Fall Meeting