Improving Sub-Grid Scale Accuracy of Regional Finite Difference Models

Management and sustainability of groundwater resources are often evaluated by use of finite difference models. The scale of the modeling effort is often related to the scale of the management or sustainability evaluation. Large finite difference models encompassing several counties or states applied for regional evaluations incur errors due to the large grid-block size at river, drain, or well boundary locations. This causes practitioners to refine the grid in the vicinity of these boundary features, so as to have them located at or close to grid-block centers. A scheme is presented to improve resolution in these cases without grid refinement. Examples are presented to demonstrate speed and accuracy of these methods.