Analysis, Wyoming Gap , 1996, Snake/Salt River Basin Plan - Major Streams: Spatial Data and Visualization Center, Laramie, Wyoming.Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378206.400000.
The flattening of the ellipsoid used is 1/294.978698.
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 50 |
Sequential unique whole numbers that are automatically generated.
| Formal codeset | |
|---|---|
| Codeset Name: | Arc (line) feature codes |
| Codeset Source: | USGS DLG data user guide, also see attached file, HYDRODLG.LINE |
Coordinates defining the features.
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 7 |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 50 |
| Formal codeset | |
|---|---|
| Codeset Name: | Polygon feature codes |
| Codeset Source: | USGS DLG data user guide, also see attached file, HYDRODLG.POLY |
| Formal codeset | |
|---|---|
| Codeset Name: | Line feature codes |
| Codeset Source: | This file, HYDRODLG.LINE |
| Formal codeset | |
|---|---|
| Codeset Name: | Line feature descriptions |
| Codeset Source: | This file, HYDRODLG.LINE |
| Formal codeset | |
|---|---|
| Codeset Name: | Arc/Info COLOR lineset |
| Codeset Source: | Arc/Info software |
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 15127 |
| Formal codeset | |
|---|---|
| Codeset Name: | Polygon feature codes |
| Codeset Source: | This file, HYDRODLG.POLY |
| Formal codeset | |
|---|---|
| Codeset Name: | Polygon feature descriptions |
| Codeset Source: | This file, HYDRODLG.POLY |
| Formal codeset | |
|---|---|
| Codeset Name: | Arc/Info COLOR lineset |
| Codeset Source: | Arc/Info software |
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 8172 |
| Formal codeset | |
|---|---|
| Codeset Name: | Stream order codes |
| Codeset Source: | this file, HYDRODLG.ORDER |
| Formal codeset | |
|---|---|
| Codeset Name: | Arc/Info COLOR lineset |
| Codeset Source: | Arc/Info software |
| Range of values | |
|---|---|
| Minimum: | 1684 |
| Maximum: | 41557 |
200=Shoreline 412=stream 605=right bank 606=left bank 420=wash 103=glacier boundary 201=man-made shore 406=dam or weir 202=closure line 203=indefinite shore (identifies high-water mark) 204=apparent limit 400=rapids 401=falls 610=intermittent (all else assumed perennial)Definitions for polygon attribute values (.PAT):
101=reservoir 103=glacier 105=inundation area 108=submerged area (due to dam-building) 109=sewage pond 110=tailings pond 111=marsh/wetland, 402=gravel pit 412=wide river (represented by left and right bank) 420=emphemeral wash 421=lake or pond.
United States Geologic Survey National Mapping Program, data source. Edgematching, corrections, ordering: Margo Berendsen, Tom Kohley - Wyoming Gap Analysis project.
Data Manager
Spatial Data and Visualization Center
Box 4008 University Station
Laramie, Wyoming 82071
USA
307-766-2751 (voice)
n/a
- Hours_of_Service: 8:00 - 5:00 MST
The purpose of this data layer was to provide a base layer of water features at a statewide level for riparian/aquatic species distribution modeling for the Wyoming Gap Analysis project. However the data may also be used for a variety of other natural resources management/biological studies at the appropriate scale.
U.S. Geological Survey, National Mapping Program, 1994, Digital Line Graphs for Hydrography.
Metadata imported.
Data sources used in this process:
This product is directly derived from the USGS DLGs, which according to the National Mapping Program do not currently carry quantified accuracy statements. However, procedures used by the NMP to validate the attribute accuracy involve computerized checking of attribute codes against a table of valid codes to endure that each attribute in a file is valid for the category. A manual process involving proof plots is used to verify correct application of codes. The additional attribute added by Wyoming Gap Analysis, stream order, automatic generation by a ordering program. The coding was checked by displaying each order as a different color on screen, and special attention was paid to braided streams or other complicated areas of stream connection. The Strahler order attributes are correct only so far as the connectivity and completeness of the hydrographic network is represented due to generalizations at the 1:100,000-scale. Obviously, there will be differentiation in order at the larger 1:24,000-scale because of the more accurate representations of streams at that scale. Attributes were also checked by visual color displays for intermittent and perennial attributes, as well as natural vs. man-made (all ditches, canals and aqueducts were removed). One section of Wyoming should be noted in particular for incorrect attributing which was corrected by Wyoming Gap Analysis: streams in Weston county, particularly the Lance Creek 1:100,000 quadrangle, were incorrectly labeled as perennial when, according to USGS 1:24,000-scale topographic maps, they were actually intermittent streams. Some linear features were corrected where they were man-made ditches/canals but incorrectly labeled as natural streams (primarily in the Pinedale quadrangle). Approximately 12% of the 1,792 1:24,000-scale topographic maps for Wyoming were used to verify the 1:100,000-scale DLGS, however these quads were not statistically selected for verification but rather were selected to check areas that had already been identified as "problem areas".
The USGS NMP identifies these procedures used to qualify the positional accuracy of their DLG products: the data are either manually digitized using equipment with a resolution of 0.001 inch and an absolute accuracy of from 0.003 to 0.005 inch, or are scanned on an automatic device with a resolution of 30 points per millimeter, or 0.0013 inch. The positional accuracy of the data and complete- ness of the file are checked by visually comparing proof plots with the original stable-base source material. These proof plots are generated using automated drafting machines with a resolution of 0.001 inch and an absolute accuracy of from 0.003 to 0.005 inch. Wyoming Gap Analysis converted raw DLG data into Arc/Info format with a 2 meter fuzzy tolerance (minimum distance between coordinates). Wyoming Gap Analysis also performed manual edge-matching along boundaries of 1:100,000-scale quadrangles of the source DLG data in Arc/Info, any positional offsets less than or equal to 200 meters being snapped together by splitting the distance between the two arcs. Other editing performed by Wyoming Gap Analysis which may or may not have an effect on the positional accuracy included adding or moving arc vertices and adding or lengthening arcs to join existing features in the edge-matching process. Grain tolerance used in adding/editing arc vertices was < 50m. Approximately 12% of the 1,792 1:24,000-scale topographic maps for Wyoming were used to verify the 1:100,000-scale DLGS, however these quads were not statistically selected for verification but rather were selected to check areas that had already been identified as "problem areas", areas where its was not possible to determine how to connect streams along quadrangle edges by referring to the 1:100,000-scale maps alone.
Some attributes may have a zero value because of the hierarchical nature of the DLG MAJOR and MINOR attributes (see the USGS National Mapping Program Digital Line Graphs Data Users Guide 2 for more details). The attribute added by Wyoming Gap Analysis, stream order, is complete for all linework (Arc/Info arc attribute table), line features being labeled as zero corresponding to water features which are not ordered, eg. lakes, ponds and reservoirs. It should be noted that Wyoming Gap Analysis identified the two Yellowstone National Park quadrangles in the northwestern corner of the state to be mapped in less detail than surrounding quadrangles, (not just in the DLG product, but also on the original USGS 1:100,000-scale paper topological maps). Apparently different decision rules were applied by the NMP in translating hydrography from the 1:24,000-scale down to the 1:100,000-scale for this region of the state, and the data for these two quads should be considered as incomplete in comparison to the level of detail mapped for adjacent areas.
There are no unclosed polygons, intersections without nodes, or polygons without labels or with more than one label. Arc/Info's topological checking program CLEAN was used to correct intersections without nodes, identify unclosed polygons and remove duplicate lines with the same beginning and ending nodes. Checks were not made for possible errors such as sliver polygons or duplicate lines missed by CLEAN, though if any such errors exist they are likely to be minor due to the topological tests performed on the raw DLG data by the USGS NMP.
Are there legal restrictions on access or use of the data?
- Access_Constraints: none
- Use_Constraints:
- Wyoming only. This data should never be used a scale larger than 1:100,000. The data is only as accurate as the source maps it was produced from, and use is dependent on the date of the sources and quality at which they were produced.
Data Manager
Spatial Data and Visualization Center
Box 4008 University Station
Laramie, Wyoming 82071
USA
307-766-2751 (voice)
n/a
Downloadable Data
The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate used described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor described above and not indirectly through other sources which may have changed the data in some way. This data was developed and is meant to be used at the 1:100,000-scale (or smaller scale) for the purpose of identifying hydrographic feature locations in Wyoming. makes no claims for the data's suitability for other purposes.
| Data format: | ARCE (Arc/Info export) (version 7.0.4) Size: 70.9 |
|---|---|
| Network links: |
ftp.sdvc.uwyo.edu or <http://www.sdvc.uwyo.edu/clearinghouse> |
No fees are required for downloading the data that is on-line. Some fees may be required to cover costs of tapes if data is required on tape media.
Margo Berendsen
Box 4008 University Station
Laramie, Wyoming 82071
USA
307-766-2751 (voice)
meh@uwyo.edu
