US Army Corps of Engineers
Philadelphia District & Marine Design Center

Delaware Inland Bays and Delaware Bay Coast Coastal Storm Risk Management Feasibility Study

Published July 16, 2019


APPROPRIATION / PHASE: General Investigations 

AUTHORITY: U.S. House of Representatives Committee on Public Works and Transportation Resolution on October 1, 1986 and U.S. Senate Committee on Environment and Public Works Resolution on June 23, 1988 

DESCRIPTION: The Delaware Inland Bays and Delaware Bay Coast (DIBDBC) Focus Area includes the Delaware Inland Bays, the set of interconnected bodies
of water that are separated from the Atlantic Ocean by a spit of land, and the Delaware Bay coastline of the State of Delaware in New Castle, Kent, and Sussex Counties. The Inland Bays coastline area is approximately 77 square miles and the Delaware Bay coastline is approximately 145 square miles. The authorities for the DIBDBC Study (Resolutions adopted by U.S. House of Representatives on October 1, 1986 and the U.S. Senate on June 23, 1988) support North Atlantic Coast Comprehensive Study (NACCS) outcomes, are broad in scope and application and address the development of a physical and engineering database as the basis for actions and programs to provide shoreline protection and up-to-date information for state and local management of this coastal area. 

The DIBDBC Study is being performed to align with the goals of the NACCS, which are to:

  • Provide a risk management framework, consistent with and NOAA/ USACE Infrastructure Systems Rebuilding Principles; and
  • Support resilient coastal communities and robust, sustainable coastal landscape systems, considering future sea level and climate change scenarios, to reduce risk to vulnerable populations, property, ecosystems, and infrastructure.

The objective of the DIBDBC CSRM Study is to investigate coastal storm risk management problems and solutions to reduce damages from coastal flooding affecting population, critical infrastructure, critical facilities, property, and ecosystems. The study will consider past, current, and future coastal storm risk management and resilience planning initiatives and projects underway by the USACE and other Federal, State, and local agencies. Three overarching efforts will be performed: 

  • Assess the study area’s problems, opportunities and future without project conditions;
  • Assess the feasibility of implementing system-wide coastal storm risk management solutions such as policy/programmatic strategies, storm surge barriers at selected inlet entrances, or tidal gates at selected lagoon entrances; and
  • If system-wide solutions are not feasible, assess the feasibility of implementing site-specific solutions, such as a combination of structural, non-structural, and natural and nature-based features.

The end product of this study will be a decision document in the form of a Chief’s Report authorizing comprehensive USACE design and construction opportunities using the full array of CSRM strategies and measures for community-based solutions within a watershed-based, systems framework. Also included in the report would be recommendations of actionable and policy implementable items for non-USACE entities, including floodplain management, landscape architecture, hurricane evacuation plans, and Community Rating System enhancement opportunities. Additional recommendations will be provided for incorporating existing
USACE and external programs, projects, plans and actions, as well as public-private partnership opportunities into the NACCS DIBDBC study umbrella. A programmatic NEPA document will be developed identifying a range of impacts. The PED Phase will include detailed design with a detailed fully compliant programmatic NEPA document which evaluates impacts for specific solutions.


  • Flood risk is increasing for coastal populations and supporting infrastructure. 
  • Improved land use, wise use of floodplains, responsible evacuation planning, and strategic retreat are important and cost-effective actions.
  • Communities should adopt combinations of solutions, including nonstructural, structural, natural and nature-based, and programmatic measures to manage risk, where avoidance is not possible.
  • Communities must identify their acceptable level of residual risk to plan for long-term, comprehensive, and resilient risk management.
  • Many opportunities exist to improve risk management, including enhancing collaboration, building new partnerships, and strengthening pre-storm planning.
  • Addressing coastal risk requires collaboration among local, regional, Tribal, State and Federal entities, NGOs, academia,
  • Resilience can be encouraged through the use of a CSRM framework and commitments to advance sea level and climate change science, and storm surge modeling and related themes. 

NON-FEDERAL SPONSOR:  Delaware Department of Natural Resource and Environmental Control


PROJECT MANAGER: Scott Sanderson