NOAA C-CAP National Wetland Potential

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Date that the source FGDC record was last modified.

Converted from FGDC CSDGM (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

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Wetland Potential Layers were used to find the likelihood of wetland potential and assess areas for potential mitigation or restoration. | Source Geospatial Form: raster digital data | Type of Source Media: Downloadable

Data Collection: This involved the acquisition of pre-existing data sets to be used in the creation of the probability rating. These data were all sourced from national geospatial programs and most were available at no charge. The input data sets and their sources are: National Wetlands Inventory (NWI) from US Fisheries and Wildlife, National Hydrology Data set (NHD) from USGS, Soil Survey Geographic Database (SSURGO) from Natural Resource Conservation Service, 30m National Elevation Data set (NED) from USGS, and satellite imagery (Landsat, but 2009 NAIP imagery for state of Washington). Where available, wetland maps from County GIS Departments were used for validation.

Pre-process data: Each data sets mentioned above was preprocessed in preparation for the comprehensive modelling step (see the last process step). This included converting vector data (NWI and NHD areas & flowlines) into the ERDAS IMAGINE raster format and resampling to a 30m spatial resolution. The SSURGO data was processed to create a percent hydric soils layer ranging from 0-100. Additionally, a slope and curvature models were derived from the 30m NED. Cloud free Landsat 7 TM scenes were acquired for each regional project.

The Hydric Soils and NHD raster were then modelled based on topographic characteristics to remove areas that did not support wetlands such as areas with high slopes and convexity. The NWI rasterized polygons were recoded to give each class a rating with a higher rating designated to the Woody wetland classes. The resulting raster layers from these preprocesing steps provided the building blocks for the probability rating.

The final step was to generate a comprehensive probability rating that combined information from the various modelled layers. Multiple models were constructed that weighted the NWI rasterized polygons and linear data, Topo modelled Soils, Topo modelled NHD Polygons and Topo modelled image segments that intersected with NHD flowlines. No single model was developed to combine all of the processed data; instead, many models were developed that contributed to the final rating. As a result, based on the combination of: inclusion in the NWI, percentage of hydric soils and location in the floodplain a layer was generated with values ranging from 0 (Unlikely) to 8 (highly likely). Areas of open water were designated as 10.