Advancements in mapping potential wetland areas across the Conterminous United States
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Considering wetland restoration at the regional, state, or watershed scale can provide targeted ecosystem services. Highly connected systems, particularly where hydrologic characteristics are foundational to the ecosystem, are more effective at providing ecosystem services compared to smaller, disjointed systems. There are currently limited resources to support landscape-level wetland planning that use consistent methods and data inputs across the conterminous United States. This study develops a map of potential wetland area, which may support restored or built wetlands to support better placement and planning in wetland restoration. The Random Forest algorithm is used to model potential wetland area in each of 18 two-digit hydrologic units that encompass the conterminous United States. Select subsystems from the National Wetland Inventory are used as training data for the algorithm to target inland shallow and estuarine subsystems. The 17 input variables used in the models include Sentinel-1 SAR imagery, topographic indices and indicators, and soil suitability. The final product of this study is a gridded dataset with 10-m resolution that identifies areas where the landscape, land use, and hydrology would likely support a built or restored wetland. The model predicted that 21.1% of the conterminous United States land can be categorized as potential wetland area, compared to the current estimate of 9.3% existing wetlands in the National Wetland Inventory. The model results were further explored on cropland to support conservation programs that encourage landowners to convert some area to wetland habitat. The resulting maps demonstrate the application of big data and machine learning to identify locations across a diverse landscape likely to support a specific ecosystem type. This product can be used to better place restoration projects to serve ecosystem- and community-wide health where placement of sites is critical to efficacy, including nutrient uptake and flood attenuation.