NOAA Guide to Assessing Green Infrastructure Costs and Benefits for Flood Reduction

NOAA provides communities with a six-step process to assess the costs and benefits of green infrastructure (GI) to reduce flooding in this report. Communities can use this guide to inform flood risk planning, and to assess the cost effectiveness of implementing green infrastructure projects. The primary steps and related actions provided in the guide are designed to lead a community to the implementation of a green infrastructure strategy for a given watershed. 

The guide is based on experiences from three pilot studies in the Great Lakes region (Duluth, Minnesota; Toledo, Ohio; and Green Bay, Wisconsin) as well as a community workshop on the He‘eia watershed in Hawaii to test transferability. Specific examples from these four case studies are also provided for each step to illustrate implementation of specific tasks and offer lessons learned.  

The six-step framework includes specific tasks, key question and considerations, case studies, and recommended expertise associated with each step. Additional key resources to support the process are provided at the end of the guide. The guide is organized into the following steps and tasks:

1. Define the Flooding Problem - Choose a watershed study area, characterize flooding issues and causes, and determine what’s at risk.

2. Assess Flooding Scenarios without Green Infrastructure - Gather data, model current and future flooding, and quantify current and future flood damages. 

3. Identify How a Flood Reduction Target Can Be Met with Green Infrastructure - Select a flood reduction target, identify green infrastructure options, and determine how much storage the GI options can provide.

4. Assess Flooding Scenarios with Green Infrastructure - Model and quantify current and future flooding if the flood reduction target is met with GI. 

5. Estimate Benefits and Costs - Estimate GI option unit costs and strategy cost, estimate GI strategy benefits and co-benefits, and annualize costs and benefits over a specific time frame.

6. Identify and Communicate the Desired Green Infrastructure Strategy - Finalize a green infrastructure strategy, and communicate the strategy and plan next steps with stakeholders

Step 3 offers examples of various green infrastructure practices and policies to help communities identify GI options and develop a customized strategy to meet their flood storage and reduction targets. Examples include stormwater fees for impervious surfaces, zoning changes, incentives for the use of GI, green roofs, blue roofs (which provide temporary rooftop water storage), living shorelines, wetland and floodplain restoration and creation, and more.

 

Publication Date: April 2015

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  • Assessment guide
  • Case study

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