SEA LEVEL WISE: Comprehensive Sea Level Rise and Recurrent Flooding StudyVirginia Beach Adaptation Strategy Report

C.J. Bodnar, PE and Sue Kriebel, PEPublic Works – Stormwater Engineering CenterMarch 11, 2020

Agenda

• Project Overview• “Sea Level Wise” Adaptation Strategy Report

• Part I – Introduction• Part II – Understanding Flood Risks• Part III – Adaptation Framework• Part IV – Watershed Strategies• Part V – The Path Forward

• Next Steps

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Project Overview

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“Sea Level Wise” – Timeline of Activities

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2015 2016 2017 2018 2019 2020

Planning• Scenarios• Conceptual

model

Study Progression• Grant award• Hazard and risk

assessment• Essential analysis to

inform design• Stormwater coordination• Policy menu

Strategy Focus• Structural Alternatives

o Conceptso Performanceo Down-selection

• Policy refinement and rankings• Neighborhood and site alternatives

Synthesis• Full Draft Adaptation Strategy Report

Finalization• Stakeholder

outreach and input

• Conclude NOAA Grant

• Feasibility and continued implementation

Informing Design• Rainfall/surge correlationo >50% of rainfall events occur during elevated water levels

• Joint-probability of rainfall/storm surgeo Concurrent rainfall/surge design values

• Regional Precipitation Trendso Atlas 14 outdatedo Heavy rainfall increasing, 20% needed over design life cycle

• Probable maximum event precipitationo Design “check storm”

• Wind Tides o Water level response to wind tide conditionso Minimum design tailwaters

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Stormwater Design Standards

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“Sea Level Wise” Adaptation Strategy Report

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“Sea Level Wise” Adaptation Strategy Report

What is the purpose? • Summarize work activities in a unified framework• Present a wide range of potential adaptation

initiatives• Relate strategies across the City’s diverse

watersheds• Provide high-level implementation timeline for

potential projects• Identify additional research needs

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How is it structured?

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PART I PART II PART III

PART IV PART V

IntroductionPART I

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Introduction

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• A Call to Action:• Observed Flooding Issues

• Becoming Sea Level Wise• Program Phases• Community Engagement• Regional Connections

Public Engagement

12Community Meeting Locations across the City of Virginia Beach

Understanding Flood RisksPART II

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Complex Flooding Pathways

West Neck Creek

Rudee Inlet

Lynnhaven Inlet

Back Bay

North Landing River

Elizabeth River Southern Branch

Elizabeth River Eastern Branch

Little Creek Inlet

Understanding Flood Risks

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• The Challenges of Rising Sea Levels • Sea Level Rise Scenarios • Recurrent Flooding• Storm Surge Flooding

Range of Federal Projections Observation-based Projections by VIMS

Understanding Flood Risks

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• Compounding Factors• Coastal-Rainfall Flooding• Urban Development • Aging Infrastructure• Groundwater Changes• Ecological Decline

• Flooding Impacts• The Cost of Inaction• Where are Losses Occurring?• Physical Damages• Indirect Economic Impacts• Social Implications

Future Distribution of Loss

Cost of Inaction

Adaptation FrameworkPART III

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Multiple Layers of Adaptation

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Prepared Communities Adapted

Structures Engineered Defenses

Natural Mitigations

Preserve Environmental Assets

Increase Natural and Nature-Based Features

Pursue an Expansive Defense Network

Regulate Building and Development

Support Risk-Mitigating Interventions

Minimize Infrastructure Vulnerabilities

Grow Educational Outreach

Promote Economic Resilience

Integrating Policy and Planning

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o Comprehensive and strategic planning

o Budgeting and financingo Community outreacho Building codes and standardso Partnerships

o Research and analysiso Land use planning and zoningo Incentives and support

programso Program and project

management

How? In order to achieve those outcomes, the City can employ a number of policy and planning tools:

Envisioning an Adapted Virginia Beach

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(City-wide)

Natural Mitigations

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Preserve Environmental Assets

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Protect and expand green infrastructure networks through land conservation and renaturalization programs.

Protected and unprotected green spaces

throughout the City

Voluntary Acquisition

Conservation Easements

Land Conservation Techniques

Development Rights Purchasing

Strategic Growth Areas

Setback and Buffers

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Increase Natural FeaturesInvest in the restoration, enhancement, and construction of natural and nature-based infrastructure that provide flood protection benefits.

Areas for the restoration and

creation of nature-based

features

Beaches and Dunes

Marshes

Maritime Forests

Seagrass

Shellfish Reefs

Living Shoreline Ecological Revetments

Non-Structural Protections

Structural Protections

Engineered Defenses

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Pursue an Expansive Flood Defense NetworkInvest in the long-term construction of a structural defense network that provides wide-reaching protection from increasingly severe coastal flood risks.

“City-wide” Alternatives

Inland Structural Defenses

In-Water Structural Defenses

Neighborhood-Scale Structural Systems

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Advantages As compared to city-wide…• Relatively quick to design and construct• Relatively less expensive • Protects from high-frequency floods

(tidal, nuisance, small storms, etc.)

Disadvantages • Inadequate flood protection against

hurricane storm surges • Often not compatible with City-wide

options

CharacteristicsWest of Lesner Bridge

East of Lesner Bridge

RudeeHeights

Sandbridgeand Sigma

Muddy Creek Road

Alignment Length (ft) 5,970 10,510 North - 3,300

South – 900 28,730 48,130

Reduced Floodplain (acres) 225 523 North – 79

South – 1,406 5,395 7,644

Structures Protected 637 1,268 North – 185

South - 220 2,782 695

Approx. Costs(Millions - 2018) $15.8 $35.5 $10.8

(combined) $61.3 $72.2

Project Benefits * $30.5 $61.3 $39.8 $323.3 $222.8

Adapted Structures

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Regulate Building & Development

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Require responsible siting, design, and construction practices for new and substantial redevelopment that are reflective of the area’s current and future flood risks.

Floodplain Ordinance Update

Coastal Zone Creation

First Floor Elevation Requirements

Critical Facility Location Conditional Permitting

Siting and Design Regulations

Priority areas for restricting, regulating,

and encouraging development.

Support Risk-MitigatingInterventions

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Provide resources and incentives to encourage flood-resilient design or retrofits on residential and commercial properties.

Priority areas for supporting risk-

mitigating interventions at the

parcel-level

Dry FloodproofingWet Floodproofing Structure Elevation

Mitigation-Reconstruction Voluntary Acquisition Green Infrastructure

Loan Program

Flood In. Rate Reduction

Fee Reductions

Property Tax Relief

City Funded Grants

Federally-Funded Grants

Site-Scale Mitigation Methods

Financial Incentives and Assistance

Minimize Infrastructure Vulnerabilities

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Engage with local and regional infrastructure and utility agencies to better understand independent and cascading vulnerabilities and make proactive investments.

Critical infrastructure

networks

Prioritized Asset Investments

Resilient Construction Standards

Operations and Maintenance

Cross-Jurisdictional Collaboration

Public-Private Coordination

Regional Commitment

Infrastructure Management Techniques

Prepared Communities

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Grow Educational OutreachDevelop programs and tools to inform vulnerable residents about their flood risk and facilitate access to mitigation, preparedness, and recovery resources.

Educational Workshops

Business Outreach

Community Partnerships

Consultation Services

Community Flood Science

Public-Facing Resources

Engagement Methods Economic Resilience TechniquesFlood Insurance

ExpansionCommunity Rating

ImprovementCultural Asset

Protection

Military Coordination

Agricultural Preservation

Green Job Growth

Promote Economic ResilienceBolster flood resiliency of the City’s economic engines through access to planning resources, technical guidance, and financial support.

Watershed StrategiesPART IV

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Watershed Approach• Each watershed has distinct

flooding challenges and opportunities

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Lynnhaven

Oceanfront

Elizabeth River

Southern Rivers

Elizabeth River7%

Lynnhaven74%

Southern17%

Oceanfront2%

Elizabeth River4%

Lynnhaven48%

Southern45%

Oceanfront3%

Today 3 ft Sea Level Rise

Applying the Adaptation Framework

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Lynnhaven

Elizabeth River

Oceanfront

Southern Rivers

Adaptation Vision

• Natural Mitigations• Living Shoreline• Marsh Restoration and

Creation• Land Conservation

• Adapted Structures• Building Elevation• Commercial

Floodproofing• Floodplain Regulation• Responsible

Development• Infrastructure Resilience

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• Engineered Defenses

• Elizabeth River City-wide Alignment

• Prepared Communities

• Residential Community Education

• Flood Insurance Expansion

• Business Outreach and Education

ELIZABETH RIVER WATERSHED

Adaptation Vision• Natural Mitigations

• Beach and Dune Nourishment

• Ecological Revetments• Land Conservation• Living Shoreline• Marsh Restoration and

Creation• Shellfish Reefs and Oyster

Restoration• Seagrass Restoration

• Engineered Defenses• Chesapeake Bay

City-wide Alignment• West and East of Lesner

Neighborhood Alternatives37

• Adapted Structures• Building Elevation• Commercial

Floodproofing• Floodplain Regulation• Responsible

Development• Infrastructure Resilience

• Prepared Communities• Residential Community

Education• Flood Insurance

Expansion• Business Outreach and

Education

LYNNHAVEN WATERSHED

Adaptation Vision

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OCEANFRONT WATERSHED

• Natural Mitigations• Beach and Dune

Nourishment• Ecological Revetments• Land Conservation• Living Shoreline• Marsh Restoration and

Creation• Shellfish Reefs and

Oyster Restoration

• Engineered Defenses• Atlantic Oceanfront

City-wide Alignment• Rudee Heights

Neighborhood Alternative

• Adapted Structures• Building Elevation• Commercial

Floodproofing• Floodplain Regulation• Responsible

Development• Infrastructure Resilience

• Prepared Communities• Flood Insurance

Expansion• Business Outreach and

Education

Adaptation Vision

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SOUTHERN RIVERS WATERSHED

• Natural Mitigations• Beach and Dune Nourishment• Ecological Revetments• Land Conservation• Living Shoreline• Marsh Terrace Creation• Seagrass Restoration

• Engineered Defenses• West Neck Creek City-wide

Alignment• Sandbridge City-wide Alignment• Muddy Creek Road City-wide

Alignment• Sigma and Muddy Creek Road

Neighborhood Alternatives

• Adapted Structures• Building Elevation• Commercial

Floodproofing• Floodplain Regulation• Responsible

Development• Infrastructure Resilience

• Prepared Communities• Flood Insurance

Expansion• Business Outreach and

Education

The Path ForwardPART V

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Planning and Coordination• Continued City Response Efforts • Planning Processes and Frameworks

• Comprehensive Planning• Hazard Mitigation• Military Collaboration and Planning• Transportation Planning • Emergency Operations Planning• Capital Improvement Programming• Operations Budgeting• Strategic Planning• Strategic Growth Area Master Planning• State Coastal Planning

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Next Steps• Council Review and Public Comment

• Completed February 28, 2020• Council Adoption of Sea Level Wise Adaptation Strategy Report

• Planning Commission Briefing – March 11, 2020• Planning Commission Public Hearing – April 8, 2020• City Council Briefing and Public Hearing – May 5, 2020

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Discussion

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