Description: The sea level rise planning area is a compound data set composed of multiple data sources. There are three main geographies covered by the data set: outer coast, estuaries, and Columbia River. The mix of datasets for each of these geographies is different in each geography, and the overall intent is to approximate the areas that will be impacted by sea level rise, using all current best available data sources. Inclusion of an area in the SLR planning area could mean permanent inundation or that the area will be impacted by high tide flooding, storm surge, or erosion events. Local governments and tribes are on the frontlines responding to these impacts. Cities and counties are confronting the perpetual challenge of balancing multiple competing public and private interests in coastal resources, made more acute by climate change. Jurisdictions will need to identify tools and options for mitigating harm to people, property, and coastal ecosystems. Cities and counties will need flexible frameworks to address coastal development subject to advancing climate impacts.The outer coast planning area includes a combination of coastal velocity flood zones from Flood Insurance Rate Maps published by the Federal Emergency Management Agency (FEMA) and coastal erosion zones published by the Oregon Department of Geology and Mineral Industries (DOGAMI). These two datasets account for flood, storm waves, and coastal erosion hazard zones. FEMA defines the coastal velocity zone as “coastal areas with a 1% or greater chance of flooding and an additional hazard associated with storm waves. These areas have a 26% chance of flooding over the life of a 30-year mortgage.” The coastal erosion dataset has gaps in its coverage, though most of the developed areas of the Oregon Coast are covered. It is anticipated that these hazard zones may experience more frequent erosion or flood events as sea levels continue to rise. The data layer includes attributes about which hazard is present (erosion, flood, or both) and the data citation.The estuary planning area includes 1.5 feet of sea level rise with a flood event water level. The flood event is a 1% chance annual flood from FEMA flood insurance rate maps, which means there is a 1% chance of a flood of that magnitude every year. This combination dataset is from a study that OCMP completed in 2017 for all of Oregon’s estuaries except for the Columbia River Estuary. While this study was completed in 2017, the data still represents an accurate portrayal of SLR and its impacts in Oregon’s estuaries when compared to the 2022 NOAA SLR Technical Report described above. The only difference is that this water level may not be reached until about 2080 or later, depending on location and global carbon emissions.7 This dataset also shows a flood event on top of SLR. The coastal flood event water levels were taken from NOAA’s extreme water level calculations at the Crescent City, Charleston, Newport, and Astoria tide stations. For more information about the methodology behind this dataset, please read the 2017 OCMP Report, “Sea Level Rise Exposure Inventory for Oregon’s Estuaries.”The Columbia River planning area includes sea level rise estimates modeled by the Lower Columbia Estuary Partnership (LCEP) in 2018. LCEP modeled sea level rise using three different sea level rise scenarios: 1.65ft, 3.28ft, and 4.92ft but did not include storm surge or flood events in their modeling. Therefore, to be consistent with the sea level rise modeling in the other estuaries that use a 1% chance annual flood event on top of 1.5ft of sea level rise, we selected the 4.92ft sea level rise scenario for the Columbia River Estuary to include in the Sea Level Rise Planning Area. This is a conservative approach to try to capture the full area in this region that may be impacted by sea level rise and its associated hazards for planning purposes.This layer is intended to be symbolized to show areas with the presence of one hazard, two hazards, or three hazards, or areas entirely surrounded by hazard(s). The sea level rise planning area can be overlaid with other GIS layers such as land uses, buildings, roads, and other infrastructure. Seeing the layers in combination allows land use planners, public works professionals, and others to identify parts of their jurisdictions that are likely to be affected by sea level rise and the activities currently taking place at those locations.
Copyright Text: Financial assistance for this guide was provided by the Coastal Zone Management Act of 1972, as amended, administered by the Office for Coastal Management, National Oceanic and Atmospheric Administration.
This guide and associated toolkit was developed by staff at Oregon’s Coastal Management Program (OCMP), which is administered by the Oregon Department of Land Conservation and Development. Multiple partners and stakeholders also provided review and support for these resources. We would like to thank those who provided input to this planning guide and associated resources: Amanda Punton, Anne Marie Skinner, Carl Hendrickson,Claire Fiegener, Denise Lofman, Felicia Olmeta-Schult, Gwen Shaughnessey, Hui Rodomsky, Katherine Daniel, Kelsey Moldenke, Lisa Phipps, Marian Lahav, Pam Reber, Pat Corcoran, Patrick Marchman, Peter Ruggiero, Randy Dana, Steven Dundas, Steven Shipsey, Tanya Haddad, TJ Moore