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Erosion IMPACT Forecasts

Forecasting the IMPACT of erosion at Alaska communities

Infrastructure Management Planning Assistance for Coastal Towns (IMPACT) is a geospatial data analysis tool created by DGGS and used to forecast the impacts of erosion on infrastructure 60 years into the future.

The DGGS Coastal Hazards Program is currently working on a project to map erosion forecasts at Alaska communities. The goals of the project are to:

  1. Map historical (1950s to ~2019) erosion rates (see the shoreline change report)
  2. forecast shorelines 60 years into the future, assuming historical erosion rates continue, and
  3. measure what existing infrastructure may be impacted and by what date.

In order to conduct this analysis, the DGGS Coastal Hazards Program created the IMPACT tool. IMPACT measures the distance between infrastructure and the most recent shoreline then produces time intervals (broken into 20-year increments e.g. 2015 to 2035) of when the shoreline is modeled to reach infrastructure.

Results of the analysis are displayed in two different maps. First, the Erosion Forecast Map shows the area around a community forecasted to erode in 20-year intervals (figure 1). The Erosion Impact Map highlights which buildings are expected to be impacted by erosion in the same 20-year intervals (figure 2); this map is also zoomed in to areas with erosion impacts. Both maps show past shorelines, forecasted erosion areas, locations of infrastructure at risk to erosion, estimated erosion impact dates, and erosion forecast uncertainty.

The IMPACT analysis and maps show vulnerabilities to erosion and are expected to be used to aid community planners in prioritizing mitigation strategies and communicate risk. This analysis is ongoing for communities in northern and western Alaska with a planned completion date of April 2021.

 Clip of erosion forecast map from Shishmaref, Alaska

Figure 1: Clip of erosion forecast map from Shishmaref, Alaska. Erosion forecast areas are symbolized by color and represent 20-year time intervals: purple 2016 to 2036, red 2036 to 2056, and yellow 2056 to 2076. Erosion forecast uncertainty is shown with a light blue polygon and bordered with a dashed grey scale line. Certain infrastructure such as the airport and landfill are shown with an arrow callout. Historical shorelines are symbolized in a grey scale and the year is displayed on the line.

Clip of erosion impact map from Shishmaref, Alaska

Figure 2: Clip of erosion impact map from Shishmaref, Alaska. Buildings forecast to be impacted by erosion are symbolized by color and represent 20-year time intervals: purple 2016 to 2036, red 2036 to 2056, and yellow 2056 to 2076. Erosion forecast uncertainty is shown with a light blue polygon and bordered with a dashed grey scale line. Certain infrastructure such as the airport and landfill are shown with an arrow callout. Historical shorelines are symbolized in a grey scale and the year is displayed on the line.

This work is funded by the Denali Commission Village Infrastructure Protection Program through the project "Systematic approach to assessing the vulnerability of Alaska's coastal infrastructure to erosion".

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