River Depth Contours | ||||||
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| Category | Hydro | |||||
| Feature Dataset Name | STAND-ALONE | |||||
| Item Name | RIVER_DEPTH_CONTOURS_OHW_PDX | |||||
| Database Type | SDE | |||||
| Originator | City of Portland | |||||
| Bureau | Bureau of Planning and Sustainability | |||||
| Publication Date | 02/22/2013 | |||||
| Abstract | Willamette and Columbia River depth contours for the City of Portland area. River depths are from ordinary high water (OHW), as measured by the U.S. Army Corps of Engineers in 2004. | |||||
| Purpose | For representing depth from ordinary high water in the Willamette and Columbia rivers. | |||||
| Supplemental Information | Source Information Ordinary High Water survey conducted by the U.S. Army Corps of engineers in 2004 (Original Publication: US Army Corps 2004 Portland/Vancouver Harbor Report, Appendix A, http://www.nwd-wc.usace.army.mil/nwp/Reports/Portland_Harbor.pdf). Bathymetric data was derived from 2008 and 2010 multi-beam surveys conducted by David Evans Marine Services. Horizontal positions were acquired with an Applanix POS/MV, combined inertial and Differential Global Positioning System (DGPS). Depths were acquired with a Reson Seabat 8101 multibeam bathymetric sonar integrated with an Applanix POS/MV positioning and motion reference system. In isolated areas where there was no other data, historical NOAA data was used. Bank topography derived from a 2007 LiDAR survey covering the Willamette River, and a 2010 LiDAR survey of the Columbia River. | |||||
| Last Dataset Update | 07/22/2020 17:36 | |||||
| Last Source Update | 07/22/2020 15:46 | |||||
| Maintenance/Update Frequency | None planned | |||||
| Extent | Portland, Oregon | |||||
| Data Type | Vector | |||||
| Shape Type | Poly Line | |||||
| Feature Count | 4307 | |||||
| Horizontal Position Accuracy | The exact horizontal/vertical accuracy of the surveys is unknown, but the surveys are considered very high quality. | |||||
| Horizontal Position Accuracy Link | Neither | |||||
| Progress | Complete | |||||
| North Bounding Coordinate | 741112.781117402 | |||||
| South Bounding Coordinate | 642507.793973118 | |||||
| East Bounding Coordinate | 7698797.80943817 | |||||
| West Bounding Coordinate | 7599469.37020919 | |||||
| Theme Keyword(s) | river depths, depth contours, bathymetry, ordinary high water | |||||
| 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 | |||||
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| Create ordinary high water surface Imported the 2004 U.S. Army Corps of Engineers ordinary high water (OHW) survey from Appendix A of the report into Excel for further processing. Original survey values were in meters, NVGD29 vertical datum. All values were converted to feet, NAVD88 datum using VERTCON, an online vertical datum conversion utility. No survey information was available for Columbia River miles 111 to 117, so those values were extrapolated from downstream miles. Transect lines were drawn roughly perpendicular to the Willamette/Columbia river channels at each mile marker (per river mile markers mapped by Portland's Bureau of Environmental Services). Each line was attributed with the surveyed OHW for that mile marker. The ends of the lines were connected into a polygon feature that was used as a boundary to interpolation. All these processing datasets are available upon request. The transect lines and the interpolation boundary were used as the parameters for the ArcGIS 10.x "Create TIN" command to generate an interpolated, continuous OHW surface. The Resulting TIN was converted to a 30 meter resolution image for further processing. | ||||||
| Generate river depth raster dataset Create an initial depth from ordinary high water (OHW) dataset by comparing the OHW water surface model to the LCREP LiDAR DEM/bathymetry elevation model using the ArcGIS Raster Calculator "SetNull" conditional function: SetNull ({LiDAR DEM/bathymetry} > {OHW Surface}, {LiDAR DEM/bathymetry} - {OHW Surface}) The result is an initial elevation model representing depths from OHW. The image was further processed in ERDAS Imagine (Version 2011) using the "Clump" and "Sieve" tools to remove all non-contiguous areas less than 10,000 pixels in area (pixels were 1 meter square). This removed areas of low elevation not contiguous to the rivers. The resulting dataset was reprojected to Oregon Stateplane, NAD HARN, and all depth values were converted from meters to U.S. survey feet. | ||||||
| Generate depth contours 2' depth contours were generated using the ArcGIS 10.x "ContourwithBarriers" tool. No barriers were used in the processing. | ||||||
Attribute Tables & Domains
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| Column Sort | Column Name | Column Alias | Column Type | Column Size | Domain Value(s) | Column Description | 1 | Contour | Contour | Numeric | 8 | | | 1 | Type | Type | Integer | 4 | | |