Davenport, Shanda

English

Old Dominion University

Old Dominion UniversityODU Digital CommonsOctober 13, 2017: New and Updated Science andProjectsHampton Roads Sea Level Rise/FloodingAdaptation Forum10-13-2017City of Virginia Beach Comprehensive Sea LevelRise and Recurrent Flooding Response PlanShanda DavenportCity of Virginia BeachFollow this and additional works at: https://digitalcommons.odu.edu/hraforum_18This Presentation is brought to you for free and open access by the Hampton Roads Sea Level Rise/Flooding Adaptation Forum at ODU DigitalCommons. It has been accepted for inclusion in October 13, 2017: New and Updated Science and Projects by an authorized administrator of ODUDigital Commons. For more information, please contact digitalcommons@odu.edu.Repository CitationDavenport, Shanda, "City of Virginia Beach Comprehensive Sea Level Rise and Recurrent Flooding Response Plan" (2017). October13, 2017: New and Updated Science and Projects. 7.https://digitalcommons.odu.edu/hraforum_18/7City of Virginia Beach Comprehensive Sea Level Rise and Recurrent Flooding Response PlanOctober 13, 2017IIJVir~niaTech Invent the Future'" De1111berry· CDMth Sm1 ® '"( ~ I Sea Level Wise V..&J A vibrant future for Virginia Beach 2 | October 13, 2017Study Goal and OutcomesGoal: Produce information and strategies that will enable Virginia Beach to establish long-term resilience to sea level rise and associated recurrent floodingOutcomes: • A full understanding of flood risk and anticipated changes over planning and infrastructure time horizons• Actionable flood resilience plans that combine engineered protection measures, accommodation, and/or land use management strategies• A fine-tuned public outreach process to advance resilience initiatives I Dewberry· " D j Sea Level Wise VJiJ A vibrant future for Virginia Beach 3 | October 13, 2017Watershed Level Plans• Economic and environmental diversity require 4 distinct plansI Dewberry· Planning Area/ Natural Resources Defining Characteristics Challenges Lynn haven / Tidal sheltered bay, estuarine, fringing marsh Oceanfront I Ocean, headland beaches, tidal inlet, bay Elizabeth River / Estuarine, fringing marshes Southern / Ocean, barrier beaches, back bays and extensive marshes Mixed residential, military, commercial, lower elevation properties with high tax base. High quality natural resources. Assets at vulnerable elevations. Dense commercial and residential development. Tourism as primary economic driver. Redevelopment opportunities. USACE Civil Works flood risk reduction project. Dense residential, commercial, industrial development. Aging infrastructure. Light residential, military, rural, recreational, waterfowl and land preserves. Agriculture important economic concern. Low elevation gradients. Addressing repititive losses from recurrent flooding and preservation of low-lying natural resources. Protecting existing development and economic base while instilling resilience as a keystone in redevelopment. Upgrading infrastructure and maintaining water-based industrial economy with higher sea levels. Establishing land use strategies that preserve resources and limit new development and infrastructure in areas susceptible to future flooding. 4 | October 13, 2017Comprehensive SLR Study ApproachtJ Dewberry· 't Dj Sea Level Wise Vli.J A vibrant future for Virginia Beach 5 | October 13, 2017Phase 1: Sea Level Rise/Recurrent Flooding Impacts • Objective: Identify the location, frequency and potential cost of existing and future flood risk to the City• How will vulnerability change with increasing flood levels due to SLR?• Where will we see the flood footprint expand? • How much more frequent will flooding occur?• What assets are vulnerable?• What are the losses, how will they change? • What assets are at the highest risk?  t Dewberry· 6 | October 13, 2017VB SLR Planning ScenariosLife Cycle AlignmentTime Horizon/Time PeriodSLR Value RelevanceUseMunicipal Planning 20-40 years2035-2055 1.5 ftComprehensive Plan & OutcomesShort end of Commercial and Utility life-cyclesVulnerability assessmentKey planning value Basis for evaluation of all adaptation strategiesCritical InfrastructureLong-term awareness AdaptiveCapacity50-70 years2065-20853.0 ftUtility Infrastructure life-cycleTransportation infrastructure lifecyclesResidential structure lifecyclesSecondary vulnerability assessment to provide insight into long-term risk Basis for long-term infrastructure decisionsEvaluate cost-effectiveness of additional protection for adaptable resilience strategiesI Dewberry· 't DI Sea Level Wise VliJ A vibrant future for Virginia Beach 7 | October 13, 2017Flood elevations - Not a static increase!• SLR Integration: • 1.5 ft SLR scenario • Added as a static increase to surge elevations• Non-linear aspects captured through re-evaluation of dune erosion and wave modeling over increased water levels.• 3 ft SLR scenario • Detailed modeling from USACE and North Carolina used to integrate non-linear response in surge elevations• Wave modeling and dune erosion also re-evaluated.I Dewberry· 8 | October 13, 2017Flood Assessment Conditions• Tidal• Daily tidal flooding• Future permanent inundation• Defined by NOAA, Mean Higher High Water• Nuisance • Wind-driven surge, extreme tide events• Repetitive losses/loss of function or service• Defined by water level analysis• Storm Surge• Nor’easters, tropical storms, hurricanes• 10-, 25-, 50-, 100-, 500-yr recurrence intervals• Defined by probabilistic analysisI Dewberry· 't DI Sea Level Wise VliJ A vibrant future for Virginia Beach 9 | October 13, 2017Hazard Assessment ProcessFlood Stillwater SurfacesIntegrate best source data into seamless 3D surfaceSLR Non-linearityApply non-linear factors to surfacesFloodplain DelineationMap new floodplains at each flood frequency Wave Hazard ModelingModel changes to wave heights/dune erosion Total Flood Elevation SurfaceBuild new 3D surface including wave effectsDepth Grids Calculate depth of flood for each conditionTo Loss EstimationI Dewberry· 10 | October 13, 2017Loss Estimation ProcessData ImprovementCollect, combine, improve City building dataLoss Estimation DatabaseRelate City database to Hazus databaseAssign Depth Damage FunctionBuilding and wave environment specific settingPerform Damage/Loss EstimationDepth-damage analysis for 5 flood frequenciesData SummarizationCompile data to City planning unitsImpacts Change in risk, risk clustersConstruction qualityReplacement valueFinished floor elevation AgeOccupancy typeContents valueI Dewberry· 11 | October 13, 2017“Whole Picture” Analyses• Rainfall/surge correlation• >50% of rainfall events occur during elevated water levels• Joint-probability of rainfall/storm surge• Rainfall/surge design probabilities• Regional Precipitation Trends• Heavy rainfall increasing• Future precipitation conditions• Up to 20% increase in design rain• Probable maximum event precipitation• Design “check storm” I :Dewberry· Return Period [years] Mid-term [2045] projected Precipitation-Frequency Curve at Norfolk Model historical GEV 15 Model future GEV (2045) Updated: using Partial Duration Series 'iii' 12 Q) ..c (.) .§. § 9 ~ ·a. ·c3 Q) a. 6 ..c '<I" N 3 2 5 10 20 Return Period [years) 50 100 200 12 | October 13, 2017Stormwater incorporation• Higher coastal water levels diminish stormwater system performance• Stormwater Conveyance• Combined Flooding• Coastal FloodingN + 13 | October 13, 2017Loss Information - Context• Losses represent today’s built environment and flood control infrastructure• In today’s dollar - future losses do not include inflation• Potential reduction of loss by flood risk management strategies NOT represented• Starting point for identification of needed policy and engineering measuresI Dewberry· " D j Sea Level Wise VJiJ A vibrant future for Virginia Beach 14 | October 13, 2017City-Wide Loss Factor Increases Over Today051015202530354010-yr 25-yr 50-yr 100-yr 500-yrLoss Factor increase over TodayRecurrence Interval1.5 ft SLR3 ft SLRI Dewberry· • • I I • • I 't DI Sea Level Wise VliJ A vibrant future for Virginia Beach 15 | October 13, 2017Projected Changes in Flood Loss$0 $50 $100 $150 $200 $250 $300 $350 $400 Today 1.5 ft SLR 3.0 ft SLRAnnualized Losses (Millions)3.5x increase 15x increase4.4x increase over 1.5 ftI Dewberry· -'t DI Sea Level Wise VliJ A vibrant future for Virginia Beach 16 | October 13, 2017Watershed Loss Changes with SLRWatershed Today 1.5 SLR 3 ft SLRElizabeth River 2.48 8.18 23.60Lynnhaven 15.97 53.27 158.14Southern 4.62 17.94 165.31Oceanfront 0.49 2.37 15.72Total: 23.56 81.76 362.77Annualized Losses, MillionsToday Oceanfront1 Southern 2% 20% Elizabeth River 10% 1.5 ft SLR Oceanfront 3% \ Elizabeth ..,,,.,- River / 10% I Dewberry· 3 ft SLR Oceanfront 4% \ Southern 46% ~El~~~~th 6% 17 | October 13, 2017Strategic GrowthAreas50-yr recurrence interval flood, 3 ft SLR Scenario02468101214161 2 3 4 5 6 7 8Total Losses, Millions of $SGA Area IDLoss by SGAToday1.5 ft Scenario 3 ft Scenario• • 0 2.5 5 I Dewberry· 10 Miles 0 0.25 0.5 1 MIies 18 | October 13, 2017Annualized Loss Concentration• Intensification and GrowthToday 1.5 ft SLR 3 ft SLR. .,l'l.g,aa!-.. . . ~q~ Legend Total Loss Low - Mild - Moderate - High Severe -,..,. • -• ._ • ., Miles j I I I 0 5 • • • • • I ~ Miles I I I 0 5 .,. ~ .. . ._ • -I · ~ • "" ".'I -~,1 .,_ -· ~ • j I Dewberry· Miles j I I 5 • • •• I ~ "t DI Sea Level Wise V.&,J A vlbrant future fer Vi,yinia. Beach 19 | October 13, 2017• Aggregated from building level risk• Efficiently ID High Risk Areas for solutionsConcentration of RiskI Dewberry· Miles 1 -----1 ---,,.------,, 0 5 N • • ·- • - r-~- •• I ~ I 20 | October 13, 2017Citywide ContextMost of the City has limited coastal flood exposure, in clustered areas• Today: <1% of buildings• In 30 years: 2% of buildings• In 60 years: 7% of buildingsBottom line: Proactive solutions can help the City avoid future losses t Dewberry· 't DI Sea Level Wise VJiJ A vibrant future for Virginia Beach 21 | October 13, 2017Projected Changes in Coastal Flooding• Areas subject to flooding will increase:• In 30-40 years: 1.5 times• In 60-70 years: 2 timesI Dewberry· All City Watersheds 250 Flood ,, Recurrence Cl) Interval ,, 200 0 0 500 Year LL ,, C 150 "' ..J .... 0 ti) 100 .!! ~ Cl) ... "' 50 :::::, CT en 0 Today 1.5 ft SLR 3 ft SLR Sea Level Rise Scenario 22 | October 13, 2017Flood Impacts• Marsh Evolution Analysis• Back Bay and North Landing River areas have the largest projected losses. • Largest losses projected for Back Bay and North Landing River• Lynnhaven – salt marsh expected to be resilient• Initial discussion of implications and results to inform strategies- i......., - CW,.H-P - lldo1Frt$11"'°"h_ Sol_ Fi. - H!l/>M""" ---p - --p 1nw,,,iF,..,, __ snn.t,/S<n.(I D e.- _ __ _ , __ ·~ ·· ~ -, 1984 t r,· 2016 ' ' " ·.,,., ,: ~ -<lE), ~a•!>• ·&_, ,<$) "se-' ay_ ' \__ ' . ., ,lwf(c" .... ,l , ~ ~ !, I ·.~ / 1 '. .h"', , §, No channel, marsh 4.t, complex sii:nificant f ' :! J 'i ....... ) ( -~~( _, Channel visible, marsh loss significant on the eastern side "t DI Sea Level Wise V.AJ A vibrant future for Virginia Beach 23 | October 13, 2017Phase 2: Adaptation Strategies• Objective: Develop, assess and prioritize a range of strategies through feasibility and cost-performance metrics to minimize short- and long-term flood risk• What planning, policy, and engineering strategies are needed to address the risk portfolio? • What policy has to be created or changed? • How can land use be managed? • Where do structural solutions make sense? • What’s the return on investment?• What strategies work best? • When should implementation occur? CITY OF VIRGIN IA BEACH COMPREHENSIVE PLAN Policy Document Re/fl(ence Handbook ~ Tochnlcs/ Document I Dewberry· APPENDIX K • FLOODPLAIN ORDINANCE ARTICLE I. · GENERAL PROVISIONS ~c. 1, 1. • Statutory authorization and purpose. A. TM ororlatlce .: .Uopt!C cunuant to th c1u1.tor1cy erar:eo to 1w e U ytUl.ltll..i f1,d,.t.hep1.JIJ)O't,l!f.lflle"1"1J":l'Ol"'IUl .... l .. l:t1JI-I l haurcts tt-e c.:;r.Jpt::in orcommerceant1,io-.'trrmental st"'1ces t flll"rt prrr~1rir ,ind rl"'hrf. ~M f"c- mr,,wl"IM" r,f thr t,n h-,~ !'ly 1 '<E'JIU.atl.,A wes. .xtlYtt es.. a~ C1eo.'tlc-or11erc that alore o, r c :ll"'\~l°"""c-rc, ~'WIii t41l'1.1' un.'lr~r-,:·.d:1.- r,cr,-.!1'1.1'"' • ., 'Ir.inti hrr 1 2 ~\11tll'I!; or~ ~1,t..~ t ,:,·i.,1'1 ,..,.in, . .<1<.lMtle lo. .,s d dt:'nr~pr't i ~u1nng11l'1V"'lo,aclrvilt-\.ardd.....,.cpmt-,1,1M1dooccur1 flooelillg .-,(I tbod <!ii Ma • '- l'ralt't.bfte ndrvuiuah. r,um ln.t)Ti i..,.ct and ,-11ULWu,•, lhdt 411e ", A.rknaNr r\!ltr,,.,ttl'\('!!drck"o"r-rth~.:,"1on.•hll'ldrl"d(I Qfr'1urio,g4.,,.~ ... ..dU)llxlll1""~ l~1, ... e a11l.l ... ~!1.,c,,,1 '-"' 1orl No. li7:"t. 11.;f,.n) 24 | October 13, 2017Example Policy/Regulatory StrategiesIncorporate resilience measures into design and siting standardsIncrease freeboard and/or require in future floodplainDownzone flood prone areas through regulation or voluntary agreementRestrict rebuilding of severe repetitive loss structuresRequire site plan review and SLR checklists for development (large or small)Develop special services districts to finance local flood control measures Provide property tax discounts or rebates for flood resilience or open space conservation Extend and improving public education and outreach about flood risks and climate change Participate in Community Rating System I Dewberry· 't DI Sea Level Wise VliJ A vibrant future for Virginia Beach 25 | October 13, 2017Evaluation and Prioritization• Qualitative: • Feasibility Scoring• Quantitative: • Cost Benefit Analysis –• Return on investment – are strategies cost-effective? FeasibilityTechnical Administrative Political Legal Fiscal EnvironmentalAccess to Needed ToolsComplexityStaffingMaintenancePolitical SupportPublic SupportConsistent with State and Federal Laws Potential Legal ChallengesCostFunding AvailabilityLimited Environmental ConsequencesConsistent with State Environmental GoalsI Dewberry· 26 | October 13, 2017Flood Risk Management Strategies• Lynnhaven Evaluation• Division of strategies into: • Structural projects with quantifiable economic benefits• Quantifiable admin. and policy measures• Non-quantifiable admin. and policy measures• Expanded, revised, and initial scoring in framework • Evaluating economic loss information to prepare benefit cost analysisFlood Impact Man;agement Str;ategy (FIMS) Lynnhaven Watershed Measure Type (VBPlan 10) Ac quisilion (S PE-2) M·,·ga.t"onRe cons-u..ct"on O,y Floodp,ooling \ie1floodproofing Coordin,a,t•S\iMvith P.orh(PLA- 81 AdIDiOlSt[atlO..aJ..:.On Add F,eebo .... d Flood Mitigation Measure(s) Associated with FIMS (Check aMthat apply) SpecificDetatls lor Lynnhaven Short Description of Proposed City- Protect ESL Measure, Protect or Action Wide Critical Loss Focus Areafs) Cost Voluntary acquisitionoflt1emost nood-proneresidentiat bui!dings TBD invarioussubdMsions DryFloodproofin11 0l nood-prone non-feSidenttal conttetel masonrybuildin11s subjedto shallow,shorl-durationnoodin!I Shorlnooctwallswherepermitted toprotectexistin11plood-prone bui!din11s tromshorl-duration noodin11 Wetnoodproofin11where TBO TBO ~;~eilli:~1::;~t~~=!s~~~o"::d- TBD damageandseMcelosses ~ajorCritical LossFoa.isAreas (L1,l2, L8) ~ajOrCritical LossFoa.isAreas (L1. l2. LS) Applied across entire Lynnhaven Watershed Appliedaa-oss entire Lynnhaven $275,0001 structure $150,0001 structure $176,0001 structure $75,0001 structure $100,0001 structure $50,0001 structure ITBO Total Feasibility 159.0 150.0 138.5 128.0 124.5 1'3.5 151.0 Total Feasibility Numeric.at Ranking 16 20 22 15 Total Feasibility Rating Med-High Med-High Medium Mid-High "t DI Sea Level Wise Vli.J A vibrant future for Virginia Beach 27 | October 13, 2017Adaptation Plan Development• City-wide policy recommendations• Watershed specific measures to address high risk areas• Sequenced to complexity, short and long-term risksHigh Risk Areas: -Flood pathway(s)-Alternative strategies-Loss avoided by strategy -Benefit cost ratio-Project cost/feasibility-Project priorityI Dewberry· 28 | October 13, 2017Phase 3: ImplementationObjective:  Integrate the best-performing adaptation strategies in actionable plans that mechanisms to ensure implementation.• How do we move forward with the preferred solutions?• What are the costs and design features? • How to we sequence the short- and long-term measures? • How do we fund? • What is our action plan for each watershed? • How do we get public buy-in, sponsors, and/or regional support?  I Dewberry· •••• Im pie mentation RESILIENCY "t DI Sea Level Wise VJi.J A vibrant future for Virginia Beach 29 | October 13, 2017Public Outreach Goal: Educate about the study and empower target audiences with accurate and timely information, and what they can do to reduce flood impactsI Dewberry· " D j Sea Level Wise VJiJ A vibrant future for Virginia Beach 30 | October 13, 2017Why is Community Outreach Important?• Most residents are unaware of the City’s resiliency efforts• There is high awareness of Norfolk’s resiliency program and improvements.• The City is assessing the 4 Watersheds for improve  resiliency• City Council committed approximately $300 million over 15 years for stormwaterimprovements• The City has made some infrastructure improvements already over the past few years• Keeping residents informed and engaged is paramount!I Dewberry· " D j Sea Level Wise VJiJ A vibrant future for Virginia Beach 31 | October 13, 2017Why Is Public Engagement Important?• Citizens must be informed with accurate and timely data• Multiple communication options must be provided to engage the public• Regular communication and updates keep the issue top of mind that the City cares about its residents and employers• Citizens can share information with others when equipped with the right communication tools • Citizen input and buy-in to future improvements and construction projectsI Dewberry· " D j Sea Level Wise VJiJ A vibrant future for Virginia Beach 32 | October 13, 2017Project ContactsBrian Batten, PhD, CFMDewberry, SLR Study Consultant804-823-6981bbatten@dewberry.com Michelle Covi, Ph.DAssistant Professor of PracticeOld Dominion University / Virginia Sea Grant Climate Adaptation and Resilience Program757-683-6598mcovi@odu.eduDavid J. Sample, Ph.D., P.E., D. WREAssoc. Professor & Extension SpecialistAREC / VPI and State Universitydsample@vt.edu Michael Morgan, P.E. CDM Smith, Stormwater Master Planning757-318-9826MorganMC@cdmsmith.comDelceno C. MilesPresident/CEOThe Miles Agency- Niche Marketing & Public Relations757-499-9627www.themilesagency.comCity of Virginia Beach - Department of Public WorksGreg Johnson, P.E., Project Managergjohnson@vbgov.comShanda Davenport, P.E.sdavenpo@vbgov.comC.J. Bodnar, P.E.cbodnar@vbgov.comI Dewberry· 't DI Sea Level Wise VliJ A vibrant future for Virginia Beach 

City of Virginia Beach Comprehensive Sea Level Rise and Recurrent Flooding Response Plan

https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1006&context=hraforum_18

City of Virginia Beach Comprehensive Sea Level Rise and Recurrent Flooding Response Plan

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