This complex 150-acre shoreline park including habitat restoration of historic San Francisco Bay wetlands was opened to the public in 2016. The East Bay Regional Park District project restored nearly 30 acres of historically filled tidal marsh habitat. WRA is conducting the annual monitoring of the restored habitats to meet regulatory agency requirements. Vegetation community and cover mapping in tidal marsh habitat poses many challenges.
To overcome these challenges WRA is using unmanned aerial vehicles (UAV, ‘drones’) to collect high resolution aerial photographs of the site that can be used for vegetation classification via remote sensing software and GIS. Ground-based vegetation community identification is first conducted to collect baseline data and to correlate aerial photo signatures with actual vegetation communities. This data is then used to classify the vegetation into similar categories based on pixel attributes. Once complete, the vegetation classification is imported into ArcGIS and shapefiles are created of the final vegetation map.
Since the drone-based aerial photo is created via orthophotogrammetry, a digital elevation model (DEM) can also be created. The DEM is extremely resolute with cm-level vertical accuracy. WRA uses the detailed DEM to assess the formations of secondary tidal sloughs. The change in the DEM from year to year can be used to calculate the area and volume of slough formation over time. To date, WRA has completed three years of drone aerial photography analysis.