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Vulnerability of Oregon Intertidal Rocky Habitats to Sea Level Change: Preliminary Area and Slope Computations using LiDAR Topobathy.
Citation:
Clinton, P. Vulnerability of Oregon Intertidal Rocky Habitats to Sea Level Change: Preliminary Area and Slope Computations using LiDAR Topobathy. a Coastal / Marine data network meeting, Corvallis, OR, March 18, 2019.
Impact/Purpose:
In response to a request for assistance from Oregon Coastal Management Program (OCCMP) to update the Oregon Territorial Sea Plan, WED researchers conducted an analysis of the vulnerability of intertidal rocky habitats to changes in sea level. Rocky shores make up 41% of Oregon’s 362-mile coastline, and attract millions of visits annually from beachgoers hoping to catch a glimpse of ocean life (Territorial Sea Plan – Rocky Shores). Using geographic information system (GIS) software, publicly available LiDAR (Light Detection and Ranging) shoreline elevation data, EPA researchers estimate that 24% of rocky intertidal area (i.e., habitat for mussels, barnacles, starfish and hundreds of other species) will be lost for every 1.0 m of increased sea level. The analysis provides OCCMP with information to manage expectations on the availability of edible intertidal shellfish and seaweeds, and the impacts to intertidal biodiversity that attracts tourists and students under various scenarios of possible sea level rise. Methods used in the analysis were developed for analyses at biogeographic scales (i.e., for the Coastal Biogeographic Risk Analysis Tool (CBRAT), and this effort demonstrates that the methods can also be applied at site-specific to state-wide scales.
Description:
On March 26, 2018 the Oregon Coastal Management Program (OCMP) issued a data request to help with the update of the Oregon Territorial Sea Plan (TSP) Rocky Shores Management Strategy. Aware of the upcoming data call and in consultation program staff, a research effort into the vulnerability of intertidal rocky habitats to sea level rise (SLR) using LiDAR topobathymetric data began in December 2017. Methods used in the analysis were developed in earlier research of such vulnerability at an ecoregions scale of the US continental west coast for the Coastal Biogeographic Risk Analysis Tool (CBRAT). As in the CBRAT study, potential loss of rocky intertidal habitat due to SLR is examined. A significant difference is that this effort analyses data at site-specific albeit state-wide scale. Another difference is that an analysis of potential change in intertidal slope was conducted after consultation with OCMP staff. A total of 85 named rocky shore sites were analyzed.Coastal topobathy LiDAR affords a detailed analysis of intertidal elevation. The Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) acquired topobathy data along the entire Oregon coast in 2009 and 2011. We used 3 meter resolution digital elevation (DEM) data derived from the LiDAR acquisition to analyze the rocky intertidal zones of the Oregon Coast.We calculated non-planimetric surface areas providing a more accurate measure of rocky intertidal habitat area because the rocky substrate supporting flora and fauna can be vertical, horizontal or at any angle. In mapping the results, area loss thresholds were adopted from CBRAT and slope change thresholds were adopted from Moorlock et al, Universidad de Puerto Rico.These methods are well documented in this research effort and the methods developed could be applied wherever topobathymetric LiDAR has been collected which currently includes the entire shoreline of the US including the shores of the Great Lakes.