EnviroAtlas - Percent Potential Wetland Area by 12-digit HUC for the Conterminous United States

The Percentage Potential Wetland Area by HUC-12 (Pct_PWA) layer shows areas where conditions may be suitable for wetland restoration or creation at a 10-m resolution. Since the 1600's, an estimated 53% of wetlands in the Conterminous United States have been lost, with many areas being converted for agricultural or urban use. The ecosystems services provided by wetlands are extremely valuable, providing flood attenuation, water filtration, nutrient sequestration, vital habitat, and many others. Wetland restoration or creation can help restore these benefits for the surrounding community. There are several government and community projects that can utilize these data to assist in site selection for wetland restoration projects. 
This layer was created using the Random Forest (RF) machine learning algorithm in Google Earth Engine (GEE). The RF model utilized 17 data inputs to identify areas where attributes on the landscape are similar to the attributes found in existing wetlands. The input data for this layer fall into three categories: topographic variables, soils, and satellite imagery. 
Topographic - DEM's sourced from USGS 3D Elevation Program (10-m)
-Elevation
-Aspect
-Slope
-Compound Topographic Index (CTI)
-Vertical Overland Flow Distance (VOFD)
-Horizontal Overland Flow Distance (HOFD)
-Pythagoras Overland Flow Distance (POFD)
-Soils - Natural Resource Conservation Service's gNATSGO and gSSURGO products
· Potential Wetland Soils (PWS)
-European Space Agency's Sentinel-1 Synthetic Aperture Radar (10-m) 

Using these variables, the Random Forest model was run for each 2 digit Hydrologic Unit Code (HUC) in Google Earth Engine. The model used wetlands from the National Wetland Inventory (NWI) to create training data, masking out deep water areas such as the centers of lakes and rivers, and excluding estuarine and marine wetlands. For each HUC an equal number of wetland an non-wetland training points proportional to the size of the HUC were generated, with 30% of those points being reserved for accuracy assessment. The model results were then summarized to calculate the areal coverage of PWA within each HUC-12 watershed in the United States.

This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

Tags: 020:072, 020:121, 12-digit hucs, alabama, arizona, arkansas, california, colorado, connecticut, delaware, ecology, ecosystem, ecosystem services, enviroatlas, environment, environmental atlas, florida, georgia, idaho, illinois, indiana, iowa, kansas, kentucky, land cover, louisiana, maine, maryland, massachusetts, michigan, minnesota, mississippi, missouri, montana, nebraska, nevada, new hampshire, new jersey, new mexico, new york, north carolina, north dakota, ohio, oklahoma, oregon, pennsylvania, rhode island, south carolina, south dakota, tennessee, texas, united states, utah, vermont, virginia, washington, washington dc, water, west virginia, wetlands, wisconsin, wyoming
Organization: U.S. Environmental Protection Agency