The U.S. Army Corps of Engineers North Atlantic Coast Comprehensive Study risk management framework: A case study application of the methodology to assess exposure and risk to coastal storm hazard in Monmouth County, New Jersey

摘要

Following the devastation caused by Hurricane Sandy, Congress passed the Disaster Relief Appropriations Act of 2013 (Public Law 113-2). The law included the authorization and appropriations for a multi-agency team, led by the U.S. Army Corps of Engineers (USACE), to complete the North Atlantic Coast Comprehensive Study (NACCS), with a final report delivered to Congress in January 2015. The NACCS includes a goal of providing a coastal storm risk management framework, defined as a process to address flood risks to vulnerable coastal populations. The study was designed to be customizable for use by states and local communities to identify their flood risk, and plan and implement strategies to reduce current and future risks. The framework presents nine steps intended to be repeated at different scales (or tiers), with the Tier 1 and Tier 2 analyses (as presented in the NACCS report) focusing on the first five steps: (1) initiate analysis, (2) characterize conditions, (3) analyze risk and vulnerability, (4) identify possible solutions, and (5) evaluate and compare solutions. Tier 1 represents the application of the framework at the NACCS study area scale, which extends from coastal Virginia to Maine. Tier 2 represents the application of the framework at a state or watershed scale. Tier 3 represents the application at a local scale (not completed as part of the NACCS). The purpose of the tiered approach is to ensure the varying degrees of stakeholder engagement, and to use appropriate inputs that reflect the priorities of the area being evaluated. In Step 3 of the framework (analyzing risk and vulnerability), vulnerabilities are classified according to three exposure categories: (1) population density and infrastructure, (2) social vulnerability, and (3) environmental and cultural resources. The probability of experiencing a hazard combined with the consideration of exposure are used to identify areas of relative risk. Once these areas are determined, appropriate measures, strategies, and studies can be identified to manage coastal storm risk. As presented in the NACCS report, this framework is applied at the study area scale as a Tier 1 analysis, encompassing all coastal areas impacted by Hurricane Sandy within the USACE North Atlantic Division (NAD). The Tier 2 analyses of this framework is performed at the state or watershed scale, and throughout nine focus areas identified as needing additional analysis, including areas of estuaries and back-bays that are subject to coastal flooding. This article demonstrates a detailed execution of Step 3 of the NACCS Coastal Storm Risk Management Framework at a Tier 2 level, spatially analyzing the risk and vulnerabilities, for two tidally influenced river basins in New Jersey, the Navesink and Shrewsbury Rivers that were severely impacted by Hurricane Sandy. This article provides details on how to incorporate necessary data to evaluate exposure and risk of coastal flooding and how to spatially identify areas of relative exposure and risk using local and national datasets.