Matt Macander of ABR, Inc. will present "Extensive mapping of coastal change in Alaska by Landsat time-series analysis, 1972–2013". The landscape-scale effects of coastal storms on Alaska's Bering Sea and Gulf of Alaska coasts includes coastal erosion, migration of spits and barrier islands, breaching of coastal lakes and lagoons, and inundation and salt-kill of vegetation. In areas experiencing moderate to large effects, changes can be mapped by analyzing trends in time series of Landsat imagery. ABR, Inc.—Environmental Research & Services and the Western Alaska Landscape Conservation Cooperative (WALCC) performed a time-series trend analysis for over 22,000 kilometers of coastline along the Bering Sea and Gulf of Alaska over the time period 1972–2013.
An annual time-series of suitable Landsat imagery was compiled and analyzed for changes in near-infrared reflectance to identify areas that transitioned from land to water, or vice-versa. Thousands of coastal changes over the 42-year study period exceeded the 60-m pixel resolution of the Multispectral Scanner (MSS) data, including coastal erosion and aggradation, estuarine and delta channel dynamics, coastal lake drainage and expansion, and migrations of coastal spits. Coastal erosion was mapped for approximately 100 km² and coastal aggradation was mapped for approximately 113 km². Although an accuracy assessment based on review of patches >5 ha in size suggested that aggradation was slightly overmapped in tidal flat areas, coastal erosion and aggradation overall were close to balanced. Locally, many areas with changes appeared to have steady state coastal dynamics, with eroding sediment aggrading nearby. Many local examples of directional change (e.g., substantial and sustained coastal erosion) were also observed. An in-progress analysis of changes in temporal trends in the rate of erosion / aggradation events will be summarized. The data products of the study will be summarized, including: raster maps of change by type, physiography class, and year; point and polygon maps of change patches; and annual Landsat mosaics for the entire WALCC coastline.
You can either join the presentation in Anchorage at the U.S. Fish & Wildlife Service Regional Office, 1011 E. Tudor Rd., Anchorage, Office of Science Applications Conference Room (1st floor) or connect to the webinar online:
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