Some of the more important values of GIS lie not in map storage, presentation, or telecommunication, but in the use of geo-location for coincidence tabluation and complex modeling. This Web document has emphasized individual basic data layers because we assume that other researchers and planners will want primary building blocks for their own analyses. However, some results of modeling efforts and related work are given below by way of example.
This example shows the mouth of the Petaluma River near the entrance to San Francisco Bay. The GRASS tool Neighbors was used to compute the number of different wetland types occuring within an 81 cell box surrounding a target cell (that is, four, 50x50 meter cells on each side of the target cell). The image on the left (below) shows: The full NWI wetlands raster file, with the same information as a vector file superimposed. Also shown as a vector file (in red) is the outer boundary of historic marshlands: the Nichols & Wright line (USGS).
The center image shows the results of the GRASS Neighbors analysis, with cells having six different categories within the matrix shown in yellow, five categories (orange), four categories (red), and three (green); plus the NWI vector file (black) and the Nichols & Wright line (red). This shows how high-diversity sites are distributed, and of special interest, indicates that a large proportion of such sites are located on or near the Nichols & Wright line.
While the level of wetlands complexity is a function of the NWI classification system itself, the findings are a useful place to start in looking for high levels of habitat interspersion.
The oblique aerial photo is of the same area, showing tide flats, tidal marsh, farmed wetlands, and freshwater ponds.
|SF Bay shoreline and Pacific coastline: 1:12K true color, CA State
This example shows a 1:12K color of the Bay edge near Hurcules.
|In this example, the photo has been converted into a GRASS raster file, and rectified to vector coverage of the shoreline digitized from 1:24K USGS quads by the State Lands Commission. The shoreline vector file (shore@slc) is shown in red.|
As part of the UC Berkeley Digital Environmental Library research project (headed by the Computer Science Division and the School of Information Management & Systems) (see UCB Digital Libraries Project ), aerial photography is being scanned for inclusion in the Library database, and for integration with text materials (EIS's, Technical Reports) and GIS coverage. These photos will be rectified, but pending the availability of a more refined digital elevation model, these will not be accurately geo-referenced. A browsing tool is being developed (project name: Eureka), and photo centers will appear as a sites file for overlay on GIS coverages. Scanning and storage are at 400 dpi, but the images portrayed here are on the order of 75 dpi.
This shows a 1:12K IR for the West Delta near Pittsburg, CA.
REGIS has incorporated data which have not been mapped but which do have accurate geographic coordinates (e.g. site files); with linkage to all other sites and to mapped information. Linking database files with digital maps of course greatly magnifies the usefulness of database and spreadsheet files. Our site files include the Regional Water Quality Control Board's "Beneficial Use" determinations of waterbodies, groundwater well information, underground storage tank (LUSTIS) files, and abandoned mining operations. This example shows how one may use the linked database for regional analysis.
All mining operations are shown below as boxed x's. Those operations that mined for mercury are highlighted in red, while those operations that mine for sand or gravel are highlighted in green, others in black. A comparison of the mercury mines and the watersheds map (vector file in brown) is just one of the possible planning applications.
This program also prepares a statistical report such as the following:
MERCURY MINES OCCURENCE REPORT: San Francisco Bay Area Location: sfbay Mapset: PERMANENT Site List: mercury_mines (20 sites) Analysis Region: north: 4284800 west: 494200 east: 648300 south: 4095900 =================================================== Layer: Watersheds Watershed : actual sites (1305) Soule Jule Reservoir 2 (1501) Walker Creek 1 (1505) Salmon Creek 1 (4101) San Francisco Bay, Lowe 1 (5309) Almaden Reservoir 1 (5311) Guadelupe Reservoir 2 (5507) Silver Creek 1 (5510) Alamitos Creek 3 (5511) Guadelupe Creek 2 (5512) Guadelupe River 1 (6509) San Antonio Creek 1 (6521) Napa River 2 (6527) Dry Creek 1 (7301) Herman Lake 1 Total 20 ====================================================
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