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The COAST Model

Updated

The COAST model can be used to manage assets with regard to specific climate change scenarios, such as sea level rise, coastal area flooding, and local disaster projection. The user can create a specific exceedance curve attaching probability of occurrence to water-level rise for a given climate change scenario over a certain time period. Multiple climate change and adaptation scenarios, each with multiple time periods, are possible (e.g., 2020, 2040, 2070, and 2100). The COAST model calculates the expected value (EV) of the damages for that climate change scenario and cumulative damages over the time period leading up to the event. 

The COAST model requires three categories of data. 

  1. Spatial data representing land elevation and assets to be modeled. 
  2. Model scenarios that are tied specifically to the spatial data.  These scenarios define the storms, sea-level rise and adaptations used to produce the model outputs.
  3. Model parameters that control the execution of the model, but are not tied to specific data layers.  This includes definitions of exceedance curves, base water level, and adaptations.  It also includes a depth-damage function (DDF) for each asset and adaptation strategy. A DDF defines the percentage of the assets value that is lost for each increment in flood depth, and is used to calculate the EV for damages.

Once the input layers, climate-change scenario, and DDFs have been identified, the tool will produce the following outputs:

  1. A KML layer showing the flooded area and the calculated damages for the defined flooding scenario. The assets will be extruded to indicate the relative amount of damages.
  2. A KML layer showing the flooded area based only on rise in sea level (without storm surge) for the scenario.  The assets in this area are permanently flooded.
  3. An Excel spreadsheet containing the cumulative expected damages for the base "no action" scenario, and for each specified adaptation.

Once the input layers, climate-change scenario, and DBFs have been identified, the tool will produce the following outputs:

  1. A KML layer showing the flooded area and the calculated benefits for the defined flooding scenario. The assets will be extruded to indicate the relative amount of damages.
  2. A KML layer showing the flooded area based only on rise in sea level for the scenario.  The assets in this area are permanently flooded.
  3. An Excel spreadsheet containing the cumulative expected benefits for the base "no action" scenario, for each sea-level rise scenario selected, and for each specified adaptation.

NOTE:  The labels and descriptions on the COAST screens will be different depending on the model being used in the current scenario.  The screens for the COAST model are shown in this document.  On the MAST screens, the word "damage" will be replaced by the word "benefit".  For example, "Depth/Damage Function" will be replaced by "Depth/Benefit Function".  In general, descriptions of data and other components apply to both COAST and MAST models, even though only one may be specifically mentioned.  Differences will be labeled explicitly.