Oregon Department of Geology and Mineral Industries2024raster digital dataOregon Department of Geology and Mineral Industries Open-File ReportO-24-07Portland, Oregon, USAOregon Department of Geology and Mineral Industries https://www.oregon.gov/dogami/Pages/default.aspxOregon Department of Geology and Mineral Industries2024Version 1.0raster digital dataOregon Department of Geology and Mineral Industries Open-File ReportO-24-07Portland, Oregon, USAOregon Department of Geology and Mineral Industrieshttps://www.oregon.gov/dogami/Pages/default.aspxThis raster dataset depicts the 50-year flood depth that is based on FEMA Flood Insurance Studies that are present within Clackamas County. The depth grid is derived from stream cross sections that contain 50-year flood elevation and lidar based terrain data. The grid is composed of pixels that represent the depth of flooding in feet. The purpose of this dataset is to provide highly detailed information about areas likely to flood during a 50-year flood event. The accuracy of the depth grid data decreases over time due to changes in the floodplain. The main sources of change is stream channel migration, bank erosion, and anthropogenic sources. Development in the floodplain often uses fill material which can impact the depth of flooding.2024CompleteNone plannedISO 19115 Topic CategorygeoscientificinformationOregon Geospatial Enterprise Office Metadata Keyword ThesaurusfloodDepth grid50-year floodflood depthOregon Geospatial Enterprise Office Metadata Keyword ThesaurusClackamasOregon Geospatial Enterprise Office Metadata Keyword Thesaurusland surfaceOregon Geospatial Enterprise Office Metadata Keyword Thesaurusrecentflood stageNoneREPORT DATA: This product is for informational purposes and may not have been prepared for or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertain the usability of the information. This publication cannot substitute for site-specific investigations by qualified practitioners. Site-specific data may give results that differ from the results shown in the publication. See the accompanying text report for more details on the limitations of the methods and data used to prepare this publication.Oregon Department of Geology and Mineral Industries mailing and physical address

800 NE Oregon Street Suite 965

PortlandOregon97232USA1 971 673 15551 971 673 1562dogami-info@oregon.govWhen contacting DOGAMI about this data set, please reference the data set title or other identifying information in your correspondence. DOGAMI publications can be downloaded from https://www.oregon.gov/dogami/pubs/Pages/pubsearch.aspxMatt WilliamsOregon Department of Geology and Mineral Industries Geohazards Analystjpeg image (.jpg)The Clackamas County Multi-Hazard Risk Assessment was funded by a grant through an Interagency Agreeement with the University of Oregon Partnership for Disaster Resilience.UnclassifiedFEMA2019modelFEMA Map Service CenterFEMAhttps://map1.msc.fema.gov/data/41/S/PDF/41053CV000A.pdf?LOC=f244c931318bc0f4fe2c12c0144447a8Pixel values are reported to the nearest one hundredth of a foot. Flood depth accuracy is constrained by the accuracy of the adopted FEMA Flood Insurance Study cross section.Pixels values were within expected range. The value range of the pixels is reasonable. The horizontal accuracy is dependent on the horizontal accuracy of river cross section layer and bare-earth DEM from which it is derived. Water surface elevations are interpolated between cross sections along the river. The cross sections were digitized at a scale of 1:500. This seems to be the greatest source of inaccuracy for the depth grid. The raster produced from the cross sections is set to 1 meter pixels to match the pixel size of the bare earth DEM. The depth is derived from these to inputs, so it retains the 1 meter pixel resolution. The vertical accuracy is dependent on the vertical accuracy of river cross section layer and bare-earth DEM from which it is derived. The cross sections do not have a vertical accuracy. The bare earth DEM has a vertical accuracy of 10cm. The vertical accuracy of the DEM would have the greatest source of inaccuracy for this depth grid.Federal Emergency Management Agency2019vector digital dataWashington D.C.FEMAhttps://msc.fema.gov/portal/advanceSearch2019FEMA, 2019Oregon Department of Geology and Mineral Industries 2009raster digital dataPortland, OROregon Department of Geology and Mineral Industries https://gis.dogami.oregon.gov/lidarviewer/2009Oregon Department of Geology and Mineral Industries 2011raster digital dataPortland, OROregon Department of Geology and Mineral Industries https://gis.dogami.oregon.gov/lidarviewer/2011Oregon Department of Geology and Mineral Industries 2013raster digital dataPortland, OROregon Department of Geology and Mineral Industries https://gis.dogami.oregon.gov/lidarviewer/2013Oregon Department of Geology and Mineral Industries 2014raster digital dataPortland, OROregon Department of Geology and Mineral Industries https://gis.dogami.oregon.gov/lidarviewer/2014A triangulated integrated network (TIN) was created from the FEMA, 2016 DFIRM cross sections using the 50-year water elevation. The TIN was then converted into a raster. This raster is subtracted from the bare-earth DEM using the "Minus" GIS tool. The output is composed of positive values (flood areas) and negative values (non-flood areas). The negative values are removed using the "Set Null" GIS tool. The resulting raster is a depth grid with pixel values indicated depth of flooding in feet. Oregon Department of Geology and Mineral Industries mailing and physical address

800 NE Oregon Street Suite 965

PortlandOregon97232USA1 971 673 15551 971 673 1562dogami-info@oregon.govWhen contacting DOGAMI about this data set, please reference the data set title or other identifying information in your correspondence. DOGAMI publications can be downloaded from http://www.oregongeology.orgVALUEPixel value represents depth of flooding in feetOregon Department of Geology and Mineral Industries mailing and physical address

800 NE Oregon Street Suite 965

PortlandOregon97232USA1 971 673 15551 971 673 1562dogami-info@oregon.govWhen contacting DOGAMI about this data set, please reference the data set title or other identifying information in your correspondence. DOGAMI publications can be downloaded from http://www.oregongeology.orgAlthough these data have been processed successfully on a computer system at the Oregon Department of Geology and Mineral Industries, no warranty expressed or implied is made by DOGAMI regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty.2024Oregon Department of Geology and Mineral Industries mailing and physical address

800 NE Oregon Street Suite 965

PortlandOregon97232USA1 971 673 15551 971 673 1562dogami-info@oregon.govWhen contacting DOGAMI about this data set, please reference the data set title or other identifying information in your correspondence. DOGAMI publications can be downloaded from http://www.oregongeology.orgOregon Department of Geology and Mineral Industries Metadata Standard1.4NoneNoneNoneNoneNone