Portland Flood Response Stages
|Feature Dataset Name||STAND-ALONE|
|Originator||City of Portland|
|Bureau||Bureau of Planning and Sustainability|
|Abstract||This layer reflects the expected impact and response required for each phase of a flood event.|
|Purpose|| To provide a visual estimate of where flooding might geographically occur during each flood response phase. Flood response phases are based on river gauge heights overlaid over LIDAR topography of the City. The flood phase levels are outlined in the PBEM 2018 FloodResponse Appendix to the Basic Emergency Operations Plan (BEOP). https://www.portlandoregon.gov/pbem/article/352778 |
|Last Dataset Update||04/11/2019 13:06|
|Last Source Update||04/11/2019 13:00|
|Extent||City of Portland|
|Horizontal Position Accuracy|
|Horizontal Position Accuracy Link|
|North Bounding Coordinate||732555.357283456|
|South Bounding Coordinate||650334.220144346|
|East Bounding Coordinate||7703200.70275591|
|West Bounding Coordinate||7604005.67158793|
|Theme Keyword(s)||Portland, Flood, Response|
|Theme Keyword Thesaurus||None|
|Place Keyword(s)||Portland, 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|
|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 - firstname.lastname@example.org
Transfer Size: varies
SPCS Zone Identifier: 5076
| File(s) |
| This layer was created by data derived from two river gauges: one gauge located on the Willamette River (https://water.weather.gov/ahps2/hydrograph.php?wfo=PQR&gage=PRTO3) and one gauge located on the Columbia River (http://water.weather.gov/ahps2/hydrograph.php?wfo=PQR&gage=VAPW1). |
The vertical datum for the river gauge data was converted from the National Weather Service Datum to NAVD88 (Geoid 03) for analysis with 2014 LiDAR digital elevation model (DEM).
Flood elevation along the rivers was mapped using river elevation cross sections maintained as a part of FEMA's National Flood Hazard Layer (available here: https://fema.maps.arcgis.com/home/webmap/viewer.html?webmap=cbe088e7c8704464aa0fc34eb99e7f30). To estimate the flood elevation along the rivers the difference between river gauge elevation and the nearest cross section was applied to all cross sections along the Columbia and Willamette Rivers. Triangulated irregular networks (TINs) representing the river flood elevations were generated for each river based off of the cross sections with the modified elevations. The TINs were then converted to rasters, and cells where the flood raster was greater than the DEM ground elevation were valued as flooded at the particular river gauge elevation phase. Where the flood extents between the Columbia and the Willamette Rivers converged, the highest cell value was used to determine if the elevation was greater or less than the ground elevation. This was done for all phases. The final outputs were then converted from a set of rasters to a single featureclass for ease of use.
|BDS_Layers||Flood Response Stages||No|
|BDS_Layers||Flood Response Stages||No|
|Column Sort||Column Name||Column Alias||Column Type||Column Size||Domain Value(s)||Column Description||1||Phase_name||Phase_name||String||50||The name of the highest phase of flooding within the record extent||1||Shape_Length||Shape_Length||Numeric||8||1||Shape_Area||Shape_Area||Numeric||8||1||Willamette_Gauge_Hts_NWSD||Willamette_Gauge_Hts_NWSD||String||50||1||Willamette_Gauge_Hts_NAVD88||Willamette_Gauge_Hts_NAVD88||String||50||1||Columbia_Gauge_Hts_NWSD||Columbia_Gauge_Hts_NWSD||String||50||1||Columbia_Gauge_Hts_NAVD88||Columbia_Gauge_Hts_NAVD88||String||50|