News: US Army Corps of Engineers releases Hurricane Sandy Coastal Projects Performance Evaluation Study
Story by Chris Gardner
NEW YORK – The U.S. Army Corps of Engineers (USACE) has completed and released the findings of the Hurricane Sandy Coastal Projects Performance Evaluation Study that was conducted in accordance with the Disaster Relief Appropriations Act of 2013 (Public Law 113-2, or often referred to as the Hurricane Sandy Relief Bill).
USACE was directed by Chapter 4 of Public Law 113-2 to evaluate the performance of existing USACE coastal projects impacted by Hurricane Sandy, with the purpose of determining their effectiveness and recommending improvements thereto.
While Hurricane Sandy’s impacts were the most pronounced in the North Atlantic region of the United States, the storm impacted communities and coastal storm risk management projects as far south as Florida and as far inland as the Great Lakes region. The Hurricane Sandy Coastal Projects Performance Evaluation Study's primary focus was an evaluation of 75 constructed coastal storm risk management projects in USACE’s North Atlantic Division, which extends from Maine to Virginia.
In addition, the Study includes evaluations of 31 projects in USACE’s Great Lakes and Ohio River Division and nine projects in USACE’s South Atlantic Division.
The performance of each of these projects was evaluated to determine the effectiveness of the project with respect to both the engineering and economic benefits and the extent to which the project reduced the overall risk to the coastal communities.
Overall, the report found that, when taking into account the varying levels of intensity of the storm in different areas with completed risk reduction projects (with storm frequencies exceeding 500-year storm levels in some areas), existing USACE projects performed as designed in reducing coastal storm risks.
Although several of the projects were over-topped by Hurricane Sandy’s record-setting storm surge in the New York and New Jersey region, the project features still provided some level of risk reduction benefits. It appears that the overall damage from the storm would have been much more severe if these projects had not been in place. Overall, coastal storm risks were greatly reduced in areas with completed risk reduction projects.
As part of the Study, the USACE team identified potential barriers to implementing coastal storm risk management projects and overall comprehensive coastal storm risk management and developed recommendations for potential improvements to how coastal risk management projects are planned, designed, constructed and maintained in the future.
The main recommendations for potential improvements to how coastal risk reduction projects are formulated are as follows:
• While in the past, projects were developed to specifically address coastal risks, their scopes (whether because of limits to authorizing language, funding constraints or other reasons) often did not consider how to address the impacts of back-bay flooding of barrier islands. Consideration should be made on how to address these issues to provide more comprehensive protection or identify the residual risks to ensure public and agency awareness.
• The efficacy of natural and engineered dunes in reducing risks of coastal storm damages should be further evaluated. Some projects with either high storm berms or those with berms backed by significant dunes generally performed better than projects involving a berm alone.
• A broader range of project benefits should be considered to more accurately evaluate the impacts of extreme storm and flooding events. These include community resilience and recovery which would be enhanced by explicitly protecting critical infrastructure and basic services.
• The data for evaluating project performance, including measurements of water levels, nearshore waves and currents, coastal winds, and pre- and post-storm topographic and bathymetric surveys, is not always readily available following storm events. The USACE should identify a limited number of strategically located projects at which to collect nearshore wave/current and coastal wind data, in coordination with other Federal, state and local agencies and partners; it should also conduct regular surveys of those projects (such as before storm season and after significant storms).
• Once a project is authorized and constructed, it can be difficult, if not impossible, to make changes or updates to the project to account for changes in external factors or risk reduction technologies or methodologies. Projects need to include an adaptive management plan or strategy for changing the design within their original authorization to respond to these factors, such as changes in local weather patterns or sediment transport, shifts in development trends or public tolerance for storm risks, changes in coastal flood risks due to climate change or changes in technology or methodology.
The entire Hurricane Sandy Coastal Projects Performance Evaluation Study can be downloaded at www.nan.usace.army.mil/SandyPPE
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