A GIS-based landscape analysis wetland function model for wetland restoration and mitigation banking

Wetland management issues are related to regulatory compliance or planning and protection activities. A wetland evaluating system with suitable modules to address wetland function, wetland banking and wetland protection to perform wetland regulatory activities is required. This research, conducted in Prince Georges County, Maryland, provides county personnel a very useful GIS-based wetland analysis tool to perform wetland regulatory activities.; This research focuses on developing a Landscape Analysis of Wetland Function (LAWF) model for use within a GIS application. Twenty-seven wetland-related variables are defined and analyzed in this research and a ranking system is established. Five different wetland functions are developed based on a different group of wetland variables and they are represented by five Functional Capacity Indexes (FCI 1 through FCI 5). A distribution map of these FCIs can be generated in a specific area for further evaluation. The LAWF method incorporates the evaluation of wetland functions compared to a reference standard of wetlands within a particular type to determine the functional condition of the assessed wetland. A wetland analysis result is a quantifiable score for each function as well as the aggregate of all the functions examined. This method makes comparing the functions of separate wetland areas possible by calculating their different Functional Capacity Unit (FCU), which is FCI multiplied by the wetland area. Using FCIs and FCUs can also eliminate the possible errors arising from using any single evaluating factor. A selection of wetlands that have FCIs within the low 25th percentile of all the wetlands in a particular watershed can be evaluated with field assessment that provides additional data needed for final site selection. An example of using the model developed shows that in the Western Branch sub-watershed, when all five FCI distribution maps are overlaid, more than 39% of the wetland polygons are overlapped. These wetland candidate polygons are most likely good mitigation banking sites. This process could be repeated for each function, varying the prioritization arrangement depending on the needs and goals of the proposed acquisition. The major contributions of LAWF can be summarized as: (1) Developed a systematic wetland assessment functions and variables. (2) Capable of generating FCI to make individual wetland comparison possible. (3) FCI can be used to perform mitigation banking activities. (4) FCU can be derived from FCI to determine the amount of wetland function lost, the residual function and the amount of function needed to be restored. (5) Customization to meet the program, or task order, requirements. (6) Reorganization to make the functional analysis conducive to a GIS environment, and the ARCVIEW standard module is extended.