Modern Baylands Background
The coverages of the Modern Landscape View of the EcoAtlas Baylands share common aerial photography origin. They are based on the best available existing regional digital information on baylands habitats. However, substantial local inaccuracies in this existing digital data have been revealed through intensive local reviews held by SFEI in December 1996 through the present. The following documentation summarizes the origin of version 1.0 of the EcoAtlas Modern Landscape View.
Substantial revision of the Modern Landscape View to incorporate hundreds of changes recommended by local experts through truthing sessions, changes in the landscape since 1985, and to implement the more detailed and regionally-representative Habitat Typology of the Goals Project is currently taking place. As a result of these changes a substantially more detailed and accurate Modern Landscape View will be available.
Version 1.0 Habitat Types
- Shallow Bay or Strait, Open Water
- Intertidal Flat
- Tidal Marsh
- Farmed Bayland
- Grazed Bayland
- Salt Pond
- Managed Wetland
- Managed Bayland, Perennial Pond
1. Origin of Coverages
National Wetlands Inventory, U.S.F.W.S, 1985
Important Additional Sources:
- USGS 7.5' Quadrangles
- BCDC Diked Baylands Study
- Tidal Marshlands Mapping, K. Dedrick
Discussion of Data Integration:
Several sources of information are incorporated into version 1.0 of the of the EcoAtlas Modern Landscape View. The dominant source is reported to be the National Wetlands Inventory (NWI) for the Bay Area. The NWI was compiled from color infrared aerial photographs at a scale of 1:58,000. The flights occurred in April 1985 at approximately mean high water (MHW). These photographs were used to produce 7.5 minute mylar maps, which were then digitized and made available to the public as Digital Line Graph files. The source(s) of these DLG files has not been ascertained.
The DLG files were imported into GRASS and used as the shoreline and upland boundaries. Individual parcel boundaries were digitized at SFEI using USGS 7.5' quadrangle paper maps (24,000 scale). The digitizer precision was +/- 0.005", and the RMS error averaged under 5 meters per quad. The first draft of the EcoAtlas was created in GRASS, and translated to ARC/INFO using the v.out.arc command (this converts the GRASS vector files to ARC/INFOs "generate" file format). All subsequent topological and feature attribute table updates were done in ARC/INFO.
Updates were of two types:
- The reclassification of parcel types;
- creation, deletion, or modification of parcel boundaries...