Metadata: Steep Slope Areas

- View Sample -

Steep Slope Areas

This page last updated: 04/03/2002
Metadata created using Minnesota Geographic Metadata Guidelines

Metadata Summary

Originator	Metropolitan Council
Abstract	This polygon dataset was derived from a raster dataset that was developed by calculating the maximum rate of change between elevation points that are 30 meters apart in a 30 meter digital elevation model grid. This dataset shows two classes of sloped areas. Class1 includes slopes from 12 to 18 percent, and class 2 includes slopes greater than 18 percent. However, there is no guarantee that such slopes exist within any given polygon in this dataset. This dataset is not suitable for determining the precise location or actual size of areas that are undevelopable due to slopes, but merely the general location of areas where development might be constrained due to steep slopes. Based on visual inspection when laying the dataset over 2000 orthophotos, the steep slope classes appear to be a reasonable representation of areas of steep slope, although these results have not been field checked. Note: This dataset was revised 10/25/2001. The previous version significantly over represented the areas of steep slope.
Browse Graphic	View a sample of the data.
Time Period of Content Date	1980
Currentness Reference	Base information is as current as the publication of its source USGS quadrangle maps which vary in publication date from 1979 to 1990.
Access Constraints	None
Use Constraints	None
Distributor Organization	Metropolitan Council
Ordering Instructions	This dataset is distributed on the internet by clicking below after 'Online Linkage'. Doing so will tell your browser to download a 'ZIP' file which will contain the following: - ArcView shape files - metadata for the dataset (.htm) - NOTICE.RTF, an important notice about this dataset that can be read by any word processing software. Additionally, this dataset is available for direct use via one or more map services. More information about what a web mapping service is can be found at http://www.datafinder.org/services/ The specific map service and layer name for this dataset can be found by clicking the blue or green boxes under the map service column of the DataFinder Catalog at http://www.datafinder.org/catalog/ .
Distribution Liability	NOTICE: The Geographic Information System (GIS) Data to which this notice is attached are made available pursuant to the Minnesota Government Data Practices Act (Minnesota Statutes Chapter 13). THE GIS DATA ARE PROVIDED TO YOU AS IS AND WITHOUT ANY WARRANTY AS TO THEIR PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE. The GIS Data were developed by the Metropolitan Council for its own internal business purposes. The Metropolitan Council does not represent or warrant that the GIS Data or the data documentation are error-free, complete, current, or accurate. You are responsible for any consequences resulting from your use of the GIS Data or your reliance on the GIS Data. You should consult the data documentation for this particular GIS Data to determine the limitations of the GIS Data and the precision with which the GIS Data may depict distance, direction, location, or other geographic features. If you transmit or provide the GIS Data (or any portion of it) to another user, it is recommended that the GIS Data include a copy of this disclaimer and this metadata.
Online Linkage	I AGREE to the notice in "Distribution Liability" above. Clicking to agree will begin the download process (See Ordering Instructions above for details.)

Full Metadata

Steep Slope Areas

Go to Section:
1. Identification Information
2. Data Quality Information
3. Spatial Data Organization Information
4. Spatial Reference Information
5. Entity and Attribute Information
6. Distribution Information
7. Metadata Reference Information


Section 1	Identification Information		Top of page
Originator	Metropolitan Council
Title	Steep Slope Areas
Abstract	This polygon dataset was derived from a raster dataset that was developed by calculating the maximum rate of change between elevation points that are 30 meters apart in a 30 meter digital elevation model grid. This dataset shows two classes of sloped areas. Class1 includes slopes from 12 to 18 percent, and class 2 includes slopes greater than 18 percent. However, there is no guarantee that such slopes exist within any given polygon in this dataset. This dataset is not suitable for determining the precise location or actual size of areas that are undevelopable due to slopes, but merely the general location of areas where development might be constrained due to steep slopes. Based on visual inspection when laying the dataset over 2000 orthophotos, the steep slope classes appear to be a reasonable representation of areas of steep slope, although these results have not been field checked. Note: This dataset was revised 10/25/2001. The previous version significantly over represented the areas of steep slope.
Purpose	This dataset shows areas where steep slopes of 12% and greater are likely to be found. There is, however, no guarantee that such slopes will be found within any given polygon in this layer. This layer is not suitable for determining the acreage of areas that are undevelopable due to slopes, but merely the general location of areas that are less likely to be developed due to slope issues, or where development might be constrained.
Time Period of Content Date	1980
Currentness Reference	Base information is as current as the publication of its source USGS quadrangle maps which vary in publication date from 1979 to 1990.
Progress	Complete
Maintenance and Update Frequency	None planned
Spatial Extent of Data	Twin Cities 7 County Metropolitan Area. This includes the counties of Anoka, Carver, Dakota, Hennepin, Ramsey, Scott and Washington in Minnesota.
Bounding Coordinates	-94.012 -92.732 45.415 44.471
Place Keywords	Twin Cities, Anoka County, Carver County, Dakota County, Hennepin County, Ramsey County, Scott County, Washington County
Theme Keywords	Steep Slopes, Slopes, Digital Elevation Models, DEM, Topography, elevation
Theme Keyword Thesaurus	None
Access Constraints	None
Use Constraints	None
Contact Person Information	Mark Kotz, GIS Database Administrator Metropolitan Council 390 Robert Street North St. Paul, Minnesota 55101-1805 Phone: 651-602-1644 FAX: 651-602-1674 E-mail: mark.kotz@metc.state.mn.us
Browse Graphic	View a sample of the data.
Browse Graphic File Description	Sample map showing the SteepSlopeAreas layer.
Associated Data Sets	30 meter DEM

Section 2	Data Quality Information	Top of full metadata	Top of page
Attribute Accuracy	This dataset shows areas were steep slopes of 12% and greater are likely to be found. There is, however, no guarantee that such slopes will be found within any given polygon in this layer.
Logical Consistency	The dataset is topologically 'clean'.
Completeness	Entire seven county geographic area is covered.
Horizontal Positional Accuracy	The DEM upon which this data is based was derived from contours from USGS 1:24,000 scale maps. Thus, the horizontal positional accuracy can probably be reasonably estimated based on the characteristics of source materials and processing techniques to be no better than +/- 45-60 feet (14 - 18 meters).
Vertical Positional Accuracy	Vertical position is not an attribute of the steep slopes data; however, these data are based upon elevation data from the 30-meter DEM. The source data is derived from 7.5 minute quads, and therefore the vertical accuracy of the source data cannot be assumed to exceed National Map Accuracy Standards for 1:24,000 scale maps with 10-foot elevation contours (+/- 5 feet).
Lineage	The process used to derive the steep slopes polygons from the 30-meter DEM is briefly described below. Step 1. Convert the elevation intervals of the 30 meter DEM from feet to meters. Step 2. Computed slope from original 30 meter DEM based on 30 meter cells using ArcView Spatial Analyst's 'Derive Slope' function. Step 3. Convert slope grid from degrees to percent as follows Percent Slope (Rise/Run) = tangent(slope_degrees/57.29578) using ArcView Spatial Analyst's 'Map Calculator' function. Step 4: Used Spatial Analyst's 'Reclassification' function to reclassify the floating point values into three integer categories. Class 1 is slopes from 0 to 12 percent, class 2 is slopes from 12 to 18 percent, and class 3 is slopes greater than 18 percent. Step 5: Use ArcToolbox wizard to convert grid to polygon coverage, remove the 0 to 12 percent slope polygons, convert to a shape file and clip to the 7-county metro area boundary. LINEAGE FOR SOURCE 30 METER DEM DATA: The software used to derive the dataset was ANUDEM ( http://cres.anu.edu.au/outputs/software.html) Input data included elevation contours derived from USGS 10-foot DLG contours, topographic depression points, and lake polygons extracted from the National Wetlands Inventory by the Minnesota DNR. Tile boundaries for the lake data were dissolved prior to processing. Lake surface elevations were calculated as zonal minimums of surface elevations for each lake. The resulting output is in a floating point grid, with units of feet. The interpolation parameters used in ANUDEM for this process were as follows: Drainage Enforcement On Elevation Data Consists Mainly of Contours Non-Negative RMS Factor = 1.0 Vertical SE = 0.0 Roughness Penalty = 0.0 (Recommended for Contour Data) Elevation Tolerance 1 = 5.0 feet Elevation Tolerance 2 = 100.0 feet Maximum Number of Iterations = 40 Elevation Units = Feet Elevation Minimum = 660.0 feet Elevation Maximum = 1230.0 feet Elevation Centered on Grid Cell Center Horizontal Position Units = Meters Grid Spacing = 30.0 X Limit (Minimum) = 410730.0 X Limit (Maximum) = 529740.0 Y Limit (Minimum) = 4913520.0 Y Limit (Maximum) = 5038710.0 Number of Columns in Output Grid = 3967 Number of Rows in Output Grid = 4173 Grid Margin = 20 cells Number of Input Files = 5 Input File 1 = input_pt.gen (ArcInfo Point Data) Input File 2 = hyps_upl.gen (ArcInfo Contour Data) Input File 3 = dem_lake.gen (ArcInfo Lake Boundary Data) Input File 4 = dem_sink.gen (ArcInfo Sink Point Data) Input File 5 = union1.gen (ArcInfo Polygon) NOTE: Drainage enforcement was used, but stream data was not used. The data have not been hydrologically corrected. Using the drainage enforcement option has the effect of filling small spurious sinks that are created as an artifact of the interpolation process. Only sinks that exceed the Elevation Tolerance 1 value (5.0 feet) or sinks that are specifically identified in the topographic depression data file will be retained.
Source Scale Denominator	24000

Section 3	Spatial Data Organization Information	Top of full metadata	Top of page
Native Data Set Environment	ArcGIS Version 8x
Geographic Reference for Tabular Data	None
Spatial Object Type	Vector
Vendor Specific Object Types	polygon shapes
Tiling Scheme	One layer for entire metro area.

Section 4	Spatial Reference Information	Top of full metadata	Top of page
Horizontal Coordinate Scheme	UTM
Ellipsoid	GRS80
Horizontal Datum	NAD83
Horizontal Units	Meters
Distance Resolution	30
UTM Zone Number	15

Section 5	Entity and Attribute Information	Top of full metadata	Top of page

Entity and Attribute Overview

Polygon Attributes: 
  
SLOPECLASS: 
     1 = Areas where slopes of 12% to 18% are more likely to be found. 
     2 = Areas where slopes greater than 18% are more likely to be found.

Entity and Attribute Detailed Citation	None

Section 6	Distribution Information	Top of full metadata	Top of page
Publisher	Metropolitan Council
Publication Date	Unpublished material
Contact Person Information	Mark Kotz GIS Database Administrator Metropolitan Council 390 Robert Street North St. Paul, Minnesota 55101-1805 Phone: 651.602.1644 FAX: 651.602.1674 E-mail: mark.kotz@metc.state.mn.us
Distributor's Data Set Identifier	SteepSlopeAreas
Transfer Format Name	ArcView Shape file
Transfer Format Version Number	ArcGIS 8x
Transfer Size	3.6 MB for zip file.
Ordering Instructions	This dataset is distributed on the internet by clicking below after 'Online Linkage'. Doing so will tell your browser to download a 'ZIP' file which will contain the following: - ArcView shape files - metadata for the dataset (.htm) - NOTICE.RTF, an important notice about this dataset that can be read by any word processing software. Additionally, this dataset is available for direct use via one or more map services. More information about what a web mapping service is can be found at http://www.datafinder.org/services/ The specific map service and layer name for this dataset can be found by clicking the blue or green boxes under the map service column of the DataFinder Catalog at http://www.datafinder.org/catalog/ .
Distribution Liability	NOTICE: The Geographic Information System (GIS) Data to which this notice is attached are made available pursuant to the Minnesota Government Data Practices Act (Minnesota Statutes Chapter 13). THE GIS DATA ARE PROVIDED TO YOU AS IS AND WITHOUT ANY WARRANTY AS TO THEIR PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE. The GIS Data were developed by the Metropolitan Council for its own internal business purposes. The Metropolitan Council does not represent or warrant that the GIS Data or the data documentation are error-free, complete, current, or accurate. You are responsible for any consequences resulting from your use of the GIS Data or your reliance on the GIS Data. You should consult the data documentation for this particular GIS Data to determine the limitations of the GIS Data and the precision with which the GIS Data may depict distance, direction, location, or other geographic features. If you transmit or provide the GIS Data (or any portion of it) to another user, it is recommended that the GIS Data include a copy of this disclaimer and this metadata.
Online Linkage	I AGREE to the notice in "Distribution Liability" above. Clicking to agree will begin the download process (See Ordering Instructions above for details.)

Section 7	Metadata Reference Information	Top of full metadata	Top of page
Metadata Date	04/03/2002
Contact Person Information	Mark Kotz, GIS Database Administrator Metropolitan Council 390 Robert Street North St. Paul, Minnesota 55101-1805 Phone: 651-602-1644 FAX: 651-602-1674 E-mail: mark.kotz@metc.state.mn.us
Metadata Standard Name	Minnesota Geographic Metadata Guidelines
Metadata Standard Version	1.2
Metadata Standard Online Linkage	http://www.gis.state.mn.us/stds/metadata.htm

This page last updated: 04/03/2002