A Geospatially Complete Wetland Vulnerability Index to Guide Wetland Monitoring and Restoration

Abstract:

Establishing a complete geospatial coverage of vulnerability within a wetland system is a powerful way to inform restoration priorities. We synthesized multiple datasets from E.B Forsythe National Wildlife Refuge, New Jersey, USA, to establish a wetland vulnerability metric that integrates a variety of physical processes. The geospatial data are based on aerial imagery, remote sensing, and hydrodynamic modeling. Specific data layers include elevation, tidal range, unvegetated to vegetated marsh ratio (UVVR), shoreline erosion, potential exposure to contaminants, residence time, marsh condition change, change in salinity, salinity exposure, and sediment concentration. First, we delineated the wetland system into individual marsh units by geoprocessing surface elevation data and then we defined a wetland vulnerability index that combined contributions from all parameters. Our analysis showed that the most influential factor on the vulnerability index was the combined effect of elevation, tide range, residence time, and UVVR. Among these factors, tide range and residence time had the highest correlation, and displayed almost co-located spatial variation. Some variables (e.g., shoreline erosion) had no significant correlation with the rest of the variables. This aggregated index allowed us to assess the overall state of a given marsh unit and assign hot spots of the most vulnerable units within the larger marsh system. Based on the established index, the dataset can further be explored to identify which drivers are most responsible for vulnerability in each unit and prioritize units for management options.