The Baylands Habitat Map 2020 (BHM2020), also known as Baylands Change Basemap (BCB), is a mapping effort designed to classify habitat types in support of Indicator 1 of the San Francisco Estuary Wetlands Regional Monitoring Program’s (WRMP). This work relies on the WRMP Habitat Type Classification System. The BHM2020 effort was funded with the goal of mapping to level 4 “Ecosystem Complex/Habitat Type” within the Classification System, for the purpose of monitoring change over time using primarily remote sensing data. Level 5 “Functional Habitat” classes, although included in the WRMP Habitat Type Classification System, require additional information to accurately map at a regional level. There are limited level 5 classes that were included in the BHM2020 mapping effort to meet the needs of a broad stakeholder group, but should be rolled up to level 4 classes when conducting accuracy assessment and change over time analysis. This is because confidence levels in the accuracy of level 5 distinctions, from using primarily remote sensing data at a regional level, are lower than the accuracy of level 4 classes. For efforts to further speciate classes to level 5 categories, additional information from other data sets and local experts is highly recommended. 

During the BHM2020 mapping effort, methods for differentiating one class from another were largely based upon relative tidal elevation, vegetation cover, and feature structure/shape. Tidal influence varies not only across the regions of the bay area, but also between bayland areas within that are constrained by levees and complex hydrological connections. To account for this variability and uncertainty, some flexibility in regard to modeled relative tidal elevation was required and adjustments based on spectral signature was necessary to accurately capture the habitats and extent of influence in areas with complex and varying tidal connections.