Truncating cross-sectional groundwater models under wetlands

Cross-sectional models are widely used in studies of flow near engineering structures, e.g. near levies and canals. In order to provide adequate model resolution, it is desirable to limit the model domain to the immediate vicinity of the canal and levy. Remote head-specified boundaries can be easily included, by truncating the model domain and using a so-called “general head boundary.” This boundary condition accounts for the resistance to flow in the aquifer from the head boundary to the boundary of the model domain. We present a similar approach for truncating the model domain underneath wetlands, which was used for the Florida Everglades. For this case a resistance parameter accounts for resistance to flow through the wetland bottom and through the underlying aquifer up to the model domain boundary. The resistance parameter is easily calculated and independent of where the model is being truncated. This type of general head boundary for flow underneath wetlands is very accurate for homogeneous aquifers, quite accurate for stratified aquifers, but a lesser approximation for multi-aquifer systems.