Cover: Nonstructural Risk Reduction Evaluation Results

Nonstructural Risk Reduction Evaluation Results

Attachment E3

Published in: 2023 Draft Coastal Master Plan, Attachment E3, Version 1 (January 2023)

Posted on rand.org Apr 4, 2023

by Michael T. Wilson, Jordan R. Fischbach, David R. Johnson, Jingya Wang, Patrick Kane, Nathan B. Geldner, Abby Littman

This attachment compiles the nonstructural project results for the 2023 Coastal Master Plan. This attachment summarizes the mitigation measures derived from the nonstructural technical analysis conducted using the Coastal Louisiana Risk Assessment (CLARA) model and informs the benefit and cost competitive programmatic budgets selected by the Planning Tool. As such, a major change from the 2017 Coastal Master Plan is that there is not a recommended suite of nonstructural projects.

While there are not specific recommendations on the implementation of nonstructural projects in the master plan, the results may be informative to other state agencies, nongovernmental organizations, community advocates, and coastal stakeholders who are interested in developing coastal hazard mitigation plans, comprehensive plans, or other nonstructural mitigation projects. Nonstructural model results include:

  • The attributes associated with different nonstructural variants;
  • A comparison of expected annual damage in dollars (EADD) versus expected annual structural damage (EASD) benefits over time;
  • An evaluation of different participation rates; Comparisons between communities;
  • A sample of community-level results; and
  • A methodological discussion of setting targets for Implementation Period 2 (IP2).

This attachment shows nonstructural results for a representative sample of 11 communities along the coast, with four communities compared in greater detail. While the Risk Assessment Team generated several variants, the team ultimately only selected two, in conjunction with the Planning Tool Team, for further analysis. The two variants correspond to a 14 ft 100-year flood depth buyout threshold for both Implementation Periods 1 and 2 (IP1 and IP2) in Years 0 and 30, respectively. The Planning Tool then used the results shown here to linearly scale the benefits associated with 25, 50, and 75% participation rates in their analysis.

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