Description: A record peak flow in February of 1996 caused the Willamette River and its major tributaries to flood. This map was created to delineate the inundated areas near the mainstem and major tributaries of the Willamette River.
Description: Areas identified by the Federal Emergency Management Agency (FEMA) as having a 1% annual chance of flooding. Known as the "Special Flood Hazard Area" (SFHA), which is also commonly referred to as the 100-year floodplain. Based on November 2010 FEMA maps, with subsequent "Letters of Map Revision" (LOMR) information incorporated as approved by FEMA.
Description: Areas identified by the Federal Emergency Management Agency (FEMA) as having a 0.2% annual chance of flooding, which is also commonly referred to as the 500-year floodplain. Based on November 2010 FEMA maps, with subsequent "Letters of Map Revision" (LOMR) information incorporated as approved by FEMA.
Description: This layer consists of polygons delineating landslide deposits (including debris flow fans and talus extent). Source: State of Oregon, DOGAMI
Description: This layer consists of polygons which delineate landslide hard scarps and scarp flanks. These head scarps or uppermost scarps in many cases expose the primary failure plane (surface of rupture) and flanks or shear zones. Source: State of Oregon, DOGAMI
Description: 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.
Description: Polygons representing slopes greater than or equal to 25% 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.
Name: Retired - Regulatory Landslide Hazard Area (BDS)
Display Field: PERIMETER
Type: Feature Layer
Geometry Type: esriGeometryPolygon
Description: <DIV STYLE="text-align:Left;font-size:12pt"><DIV><P><SPAN>Retired effective 10/01/24</SPAN></P><P><SPAN>Replacement MapService - https://portlandmaps.com/arcgis/rest/services/Public/Hazard/MapServer/32</SPAN></P><P><SPAN /></P><P><SPAN>The regulatory landslide hazard area map was created from three sources: Areas identified and mapped by Oregon Metro as earthquake hazard areas, areas delineated as zones of high landslide potential in a study conducted by Portland State University based on the mapping of more than 676 landslide events that occurred as a result of the February 1996 storms, and all land within the City that has a slope of 15 percent or greater.</SPAN></P></DIV></DIV>
Description: Relative Earthquake Hazard Map of the Portland Metro Region, Clackamas, Multnomah, and Washington Counties, Oregon, originally published in hardcopy form by Oregon Department of Geology and Mineral Industries as IMS-1 (Interpretive Map Series number one) . The digital information is current to the date of map publication, which was 1997. This digital information generally matches the published hardcopy map released as IMS-1 by the Oregon Department of Geology and Mineral Industries, Portland, Oregon. Point of contact: Geology by Matthew A. Mabey, Department of Geology, Brigham Young University; Gerald L. Black and Ian P. Madin, Oregon Department of Geology and Mineral Industries; Dan B. Meier, Woodward-Clyde Consultants, Portland, Oregon; T. Leslie Youd and Celinda F. Jones, Department of Civil and Environmental Engineering, Brigham Young University; J. Benjamin Rice, GIS Layout, Metro Regional Services, Portland, Oregon.
Description: The intent of this dataset is to depict liquefaction susceptibility from a M9 earthquake on the Cascade Subduction Zone within the Portland Water Bureau (PWB) service area and corridors along the conduits leading from the Bull Run watershed. Evaluating the potential for liquefaction and employing methods to mitigate its impacts were recognized as key factors for increasing earthquake resilience in the Oregon Resilience Plan (OSSPAC, 2013), as well as previous earthquake risk studies. Delineation of liquefaction-susceptible deposits in the PWB service area and estimating the magnitude of potential ground deformation is essential for the evaluation of potential damage from future large earthquakes in the Portland area. Mapping of liquefaction hazard allows for planning and mitigation prior to the next large earthquake and can be used for prioritizing emergency response following the earthquake.
This dataset represents liquefaction susceptibility for the City of Portland Water Bureau service area and the conduit corridors leading from the Bull Run Watershed.Geologic units susceptible to liquefaction have been attributed with a ranking, consisting of four ranked suceptibility classes ranging from Low to Very High. (A model was developed to account for five classes ranging from Very Low to Very High, however, no features fell within the Very Low classification.) Those with null "LiqExpl" values have been excluded from the analysis. Water bodies were removed. Complete methodology may be found in the draft report deliverable, Liquefaction and Lateral Spread Hazard, (InfraTerra, 2015), submitted to the Portland Water Bureau.
Copyright Text: InfraTerra Inc. and Cascade GIS & Consulting LLC.