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Computing Risk to West Coast Intertidal Rocky Habitat due to Sea Level Rise using LiDAR Topobathy
Clinton, Pat AND H. Lee. Computing Risk to West Coast Intertidal Rocky Habitat due to Sea Level Rise using LiDAR Topobathy. Esri Ocean GIS Forum, Redlands, California, November 01 - 03, 2016.
A methodology to map the extent of possible changes in the depth distributions of rocky intertidal habitat in response to sea level rise has been developed. This technique should be of great interest to aquatic resource managers in the Pacific Northwest and beyond. Rocky intertidal habitat in present in much the Pacific Northwest coast of North America and provides important ecosystem services and functions. The loss of rocky intertidal habitat due to sea level rise is of world-wide concern. The relative cost and advantages of established and emerging technologies for mapping the topography rocky intertidal will be of concern to aquatic resource managers attempting to assess impacts to ecosystem services associated with sea level rise. While the scale of this study is at a regional scale, the techniques demonstrated can be easily applied to site specific areas. Task Title: CIVA-2.1 (ACE 018) – Assessing impacts of individual and multiple climate stressors on near-coastal species at a regional scale Task Lead: Henry Lee II (WED) Task Start Date: Ongoing Task End Date: End of FY17 (with possible evolution of project into FY18/19) Task Description: The overall objectives of the research are to 1) develop a practical framework to predicting the relative vulnerability of near-coastal species to individual and multiple climate stressors at regional scales, 2) identify the primary climate stressors impacting specific species and habitats and how risk varies geographically and with different climate scenarios, and 3) use these predictions to inform regionally-specific conservation and adaption strategies including developing geographically-specific climate indicators. A related objective is to develop a web-based decision tool, the Coastal Biodiversity Risk Assessment Tool (CBRAT; http://www.cbrat.org/) for EPA and state managers, as well as to serve as a research and public outreach tool.
Compared to marshes, little information is available on the potential for rocky intertidal habitats to migrate upward in response to sea level rise (SLR). To address this gap, we utilized topobathy LiDAR digital elevation models (DEMs) downloaded from NOAA’s Digital Coast GIS data repository to estimate percent change in the area of rocky intertidal habitat in 10 cm increments with eustatic sea level rise. The analysis was conducted at the scale of the four Marine Ecoregions of the World (MEOW) ecoregions located along the continental west coast of the United States (CONUS). Environmental Sensitivity Index (ESI) map data were used to identify rocky shoreline. Such stretches of shoreline were extracted for each of the four ecoregions and buffered by 100 m to include the intertidal and evaluate the potential area for upland habitat migration. All available LiDAR topobathy DEMs from Digital Coast were extracted using the resulting polygons and two rasters were synthesized from the results, a 10 cm increment zone raster and a non-planimetric surface area raster for zonal summation. Current rocky intertidal non-planimetric surface areas for each ecoregion were computed between Mean Higher High Water (MHHW) and Mean Lower Low Water (MLLW) levels established from published datum sheets for tidal stations central to each MEOW ecoregion. Percent change in non-planimetric surface area for the same relative ranges were calculated in 10 cm incremental steps of eustatic SLR from the zonal summation. Risk of habitat loss due to SLR was defined as none (≥ 1% increase), low (0 – 10% loss), minor (11 – 29% loss), moderate (30 – 49%) loss and high ( > 50% loss). Our computed average risk of habitat loss of West Coast CONUS rocky intertidal habitat is low beginning at 0.4 m SLR, moderate at 0.8m SLR and high at 1.4 m SLR.