Floodplain Cross Sections

open.piercecountywa.gov | Last Updated 14 Aug 2020

This is 2017 DFIRM Data for cross section lines. New to the DFIRM data is the coastal flood study, that adds Velocity Zones (VE) along Puget Sound and the Seclusion Boundary. Seclusion areas are located where floodplains are affected by non-accredited levees and retain 1970s modeled flood hazards. These lines show the locations of channel surveys used to calculate flood elevations in the hydraulic models. The Cross Sections are also shown on the Flood Profiles in the Flood Insurance Study (FIS) report and can be used to cross reference the Flood Profiles to the planimetric depiction of the flood hazards. All cross sections for which a spatial location is available should be included in the S_XS table. The Cross Sections are lines generally extending from outside the floodplain, across the entire floodplain and out the other side. In this data set the cross sections have been trimmed to include only the areas show to be in a flood hazard area. Each cross section is represented by a line feature. The line has been split where the modeling shows a different base flood elevation than the stream center on the left or right bank (reference 2017 FIS Volume 2). The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event (Zones A & V), the 0.2-percent-annual- chance flood event (Zone X shaded), areas of undetermined flood risk (Zone X shaded) and areas of minimal flood risk (Zone X unshaded). The DFIRM Database is derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data, where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to earth's surface using the UTM projection and coordinate system. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12,000. Please read metadata for additional information(https://matterhorn.co.pierce.wa.us/GISmetadata/pdbswm_regulated_floodplain_x_sections.html). Any data download constitutes acceptance of the Terms of Use (https://matterhorn.co.pierce.wa.us/Disclaimer/PierceCountyGISDataTermsofUse.pdf).