Cover: Landscape Survey to Support Flood Apex National Flood Decision Support Toolbox

Landscape Survey to Support Flood Apex National Flood Decision Support Toolbox

Definitions and Existing Tools

Published Sep 7, 2017

by Aaron Strong, Debra Knopman


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Research Questions

  1. What is resilience, and how have communities incorporated resilience into decisionmaking?
  2. What is the state of analytic modeling for decision support for flood hazard mitigation?

This report summarizes the literature on definitions of resilience to flood risk, conceptual system-of-systems frameworks to analyze resilience, metric and indicator systems for measuring resilience, and examples of resilience-building in action at the community level. The literature suggests three main themes associated with the concept of resilience: (1) reducing the likelihood of a disaster and a community's ability to absorb or resist a shock, (2) increasing a system's adaptability while still maintaining function in the presence of a shock, and (3) reducing the time to recovery to normal functioning that might differ from pre-event functioning. These themes translate into capacities at the community or regional level that are essential to achieving resilience: absorptive or resistive capacity, adaptive capacity, and restorative capacity. Conceptual frameworks can be categorized into two groups: systems that segment the world by public service sectors (e.g., electric, water, and transportation) and systems that segment along functional lines (e.g., social, built, or natural).

Additionally, this report provides a catalog of decision support tools for flood mitigation efforts and provides examples of how they have been used in practice. The authors' goals were to present a structure for thinking about decision support in the context of flood risk reduction, management, and resilience; briefly overview each of the tools that meet the authors' criteria for decision support; use several examples to illustrate how these tools have been used in different settings; and make recommendations to the U.S. Department of Homeland Security about whether further investigation into the models is warranted.

Key Findings

Decision Analysis and Support Frameworks and Indicators Need to Be Tailored to Each Individual Community

  • Although some general frameworks and indicator systems are portable across communities, they must be adapted on a case-by-case basis to be useful.

As the Resilience Paradigm Has Grown, So Have Decision Support Systems and Tools and the Thinking About the Decisions Needed in the First Place

  • Decision support tools have moved from basic physical models, including maps and tabletop demonstrations and informed by historical flood patterns and basic geophysical measurements, to sophisticated hydrodynamic simulations that can produce detailed snapshots of expected property damage and infrastructure performance under thousands of futures that explore climate and other uncertainties.
  • In the United States and in many other parts of the world, the idea that government experts should design and harden infrastructure to protect citizens from flooding has shifted to a model of resilience and robustness, based not just on hard infrastructure but also on investments in natural and social capital that enable communities to mitigate impacts of flood events and recover more quickly.
  • Deep uncertainty is increasingly appreciated as an important aspect of risk analysis and risk management. This is particularly true as we enter an era of changing rainfall patterns, storm intensities, and sea levels, wherein historical patterns might no longer be reliable predictors of future conditions.


  • Any national effort focused on decision support tools (DSTs) should consider the goal of building a toolbox rather than crafting a single tool that can meet all community needs for decision support. A one-size-fits-all solution to the challenge of building community resilience to flood risk does not exist. DSTs need to be tailored to communities' needs and technical abilities.
  • Additional tools and models need to be developed to better estimate the loss following a flooding event that capture effects beyond structural damage.
  • How DSTs are disseminated to communities needs particular attention. Communities need guidance through the decisionmaking process.
  • The interdependencies among environmental, social, and other systems have not as yet been considered explicitly. This appears to be an area ripe for advancement.

The research described in this report was prepared for the U.S. Department of Homeland Security (DHS) Science and Technology Directorate's First Responders Group and conducted within RAND Justice, Infrastructure, and Environment.

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