Abstract
As one of the world's largest freshwater ecosystems, the Great Lakes Basin houses thousands of acres of wetlands that support a variety of crucial ecological and environmental functions at the local, regional, and global scales. Monitoring these wetlands is critical to conservation and restoration efforts; however, current methods that rely on field monitoring are labor-intensive, costly, and often outdated. In this article, we present a graphical user interface constructed in Google Earth Engine called the Wetland Extent Tool (WET), which allows semiautomatic wetland classification according to a user-input area of interest and date range. WET conducts multisource, moderate resolution processing utilizing Landsat 8 Operational Land Imager, Sentinel-2 MultiSpectral Instrument, Sentinel-1 C-SAR, and Shuttle Radar Topography Mission (SRTM) datasets to classify wetlands in the entire Great Lakes Basin. We evaluated classification results of wetlands, uplands, and open water from May–September 2019, and tested whether SRTM elevation, slope, or the Dynamic Surface Water Extent produced the most accurate results in each Great Lake Basin in conjunction with optical indices and radar composites. We found that slope produced the most accurate classification in Lake Michigan, Huron, Superior, and Ontario, while elevation performed best in Lake Erie. Classification results averaged 86.2% overall accuracy, 70.0% wetland consumer's accuracy, and 82.7% wetland producer's accuracy across the Great Lakes Basin. WET leverages cloud-computing for multisource processing of moderate resolution remote sensing data, and employs a user interface in Google Earth Engine that wetland managers and conservationists can use to monitor wetland extent in the Great Lakes Basin in near real-time.
Highlights
I T IS estimated that wetlands cover 3–5% of Earth’s land surface [1], [2]
Wetland Extent Tool (WET) is hosted in Google Earth Engine (GEE), as it is well suited for large-scale analysis, such as the entire Great Lakes Basin; datasets that would normally require a large amount of storage space and processing time on a local computer are instead completed within the cloud
The classification results for the entire Great Lakes Basin are presented in Fig. 3, using each basin’s most accurate results
Summary
I T IS estimated that wetlands cover 3–5% of Earth’s land surface [1], [2]. They support a variety of crucial ecological and environmental functions. Wetlands help regulate regional climate through carbon sequestration and provide critical habitat for continental and intercontinental migratory species [4]. Wetlands’ highly dynamic nature and lack of unifying land cover features pose great challenges to train algorithms to map wetlands with levels of accuracy and consistency sufficient for monitoring. For this reason, knowledge of wetland extent and distribution through comprehensive monitoring programs is a frontier of research with important applications in ecosystem conservation and land management
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