Slopes 20% or greater | ||||||
|---|---|---|---|---|---|---|
| Category | Land | |||||
| Feature Dataset Name | STAND-ALONE | |||||
| Item Name | SLOPE_20_PERCENT_LIDAR_PDX | |||||
| Database Type | SDE | |||||
| Originator | City of Portland | |||||
| Bureau | Bureau of Planning and Sustainability | |||||
| Publication Date | 11/25/2009 | |||||
| Abstract | Polygons representing slopes greater than or equal to 20% in the Portland urban services boundary area. Derived from 2014 3' resolution LiDAR bare-earth digital elevation model (DEM). All slopes average over a horizontal distance of 15'. Minimum area of contiguous slope is approximately 1/2 acre. Polygons were created, generalized and smoothed in ArcGIS 10.3.1. | |||||
| Purpose | For identifying steeply-slope areas within Portland. | |||||
| Supplemental Information | ||||||
| Last Dataset Update | 07/27/2020 17:33 | |||||
| Last Source Update | 07/27/2020 15:41 | |||||
| Maintenance/Update Frequency | Unknown | |||||
| Extent | Clackamas County, Multnomah County, and Washington County, Oregon | |||||
| Data Type | Vector | |||||
| Shape Type | Polygon | |||||
| Feature Count | 22075 | |||||
| Horizontal Position Accuracy | Refer to LiDAR DEM metadata | |||||
| Horizontal Position Accuracy Link | Taxlots | |||||
| Progress | Complete | |||||
| North Bounding Coordinate | 732263.779790306 | |||||
| South Bounding Coordinate | 651156.316599786 | |||||
| East Bounding Coordinate | 7696980.49682552 | |||||
| West Bounding Coordinate | 7603993.16116232 | |||||
| Theme Keyword(s) | slope, hazard, steep, LiDAR | |||||
| Theme Keyword Thesaurus | None | |||||
| Place Keyword(s) | Portland, Multnomah County, Washington County, Clackamas County, Oregon | |||||
| Place Keyword Thesaurus | None | |||||
| Access Constraints | Available for Public Use | |||||
| Use Constraints | These data are distributed under the terms of the City of Portland Data Distribution Policy. Care was taken in the creation of this data but it is provided "as is". The City of Portland cannot accept any responsibility for errors, omissions, or positional accuracy. | |||||
| Source Dataset Type | File Geodatabase | |||||
| Output Geodatabase | EGH_Public | |||||
| Distribution | Grid: State plane coordinate system 1983(91). Units: International feet Datum: North American Datum of 1983/1991 (HPGN) Liability: The information in this file was derived from digital databases on the City of Portland GIS. Care was taken in the creation of this file. The City cannot accept any responsibility for errors, omissions, or positional accuracy. There are no warranties, expressed or implied. Format: Shapefile or File Geodatabase Feature Class - Data will be provided via City of Portland FTP Site. Online Resource: http://portlandmaps.com/opendata Online Instructions: City of Portland Public/Open Data is distributed via the PortlandMaps Open Data Site - http://portlandmaps.com/opendata. Data not available on the PortlandMaps Open Data site can be requested by contacting the City of Portland CGIS Group - maps@portlandoregon.gov Transfer Size: varies SPCS Zone Identifier: 5076 | |||||
| Contact(s) | ||||||
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| Images |
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| Lineage | ||||||
| 03/04/2014 | Vector Data Processing All of the following processes were run in ArcGIS 10.3.1: 1. Used the "Raster to Polygon" tool to convert the raster data to polygons (no simplification). 2. Used the "Dissolve" tool with the multipart polygons option checked to create a single multipart polygon (required for step #3) 3. Used the "Eliminate Polygon Part" tool to eliminate all parts (islands/holes) less than 5,000 sq ft. ("Eliminate contained parts only" unchecked) 4. Used the "Multipart to Singlepart" tool to change back to single part polygons. 5. Used the "Simplify Polygons" tool to generalize the resulting polygons with the following parameters: POINT_REMOVE, 10' maximum offset, "Keep Points" unchecked, all other defaults. 6. Used the "Smooth Polygons" tool to smooth the polygons and make them more visually appealing. Parameters: PAEK, 45' tolerance, "Preserve Endpoints" checked, all other defaults 7. Identified with river polygons to flag areas that are underwater (river bathymetry) | |||||
| 12/09/2015 | Image processing All the steps below were performed in ArcGIS 10.3.1: 1. A percent slope raster image was created from the LiDAR DEM using the Spatial Analyst "Slope" tool using default settings (3' resolution). 2. Used the Raster Calculator SetNull function to create a new image where all slopes >= 20% are equal to 1, all other values Null. [SetNull("slope_raster" < 20, 1)] 3. Used the "Aggregate" tool to reduce the resolution from 3' to 15', averaging all slope percentages within the 15' cell (cell factor of 5, Technique = MEAN, all other defaults). 4. Clipped result to Portland urban services boundary. 5. Converted result to a 1 bit image using the CopyRaster tool [arcpy.CopyRaster_management('slope_20_raster_15ft_clip',"E:\Scratch\scratch.gdb\slope_20_raster_15ft_1bit" , "", "", "", "", "", "1_BIT") | |||||
Web Services
| Service | Description | Feature Access | Layer |
|---|---|---|---|
| BES_Layers | Referecne layers as used by various BES web content | Dynamic | Steep Slopes (20% or Higher) |
| Parks_MapWorks_UrbanForestry | Dynamic | Steep Slopes (20% or more) | |
| Hazard | Natural Hazards in and around the City of Portland. | Dynamic | Steep Slopes (20% or Higher) |
Attribute Tables & Domains
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| Table Description | ||||||
| Table Jurisdiction | ||||||
| Column Sort | Column Name | Column Alias | Column Type | Column Size | Domain Value(s) | Column Description | 1 | OBJECTID | OBJECTID | Integer | 4 | | | 1 | Is_Water | Is_Water | String | 5 | | |