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Climate Change and the Delaware River Basin

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    Climate Change:

    Impacts and Responses in the

    Delaware River Basin

    University of Pennsylvania | Department of City and Regional Planning | Fall 2008

    PennDesign Urban Design Studio

    University of Pennsylvania

    Department of City and Regional Planning

    127 Meyerson Hall

    210 South 34th Street

    Philadelphia, PA 19104

    215.898.8329 Tel

    ClimateChange

    :ImpactsandResponsesintheDelawareRiverBasin

    Fall2008

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    Prepared for the Delaware River Basin Commissionby the City Planning 702 Urban Design Studio at theUniversity of Pennsylvania

    Jonathan Barnett

    Andrew Dobshinsky

    Stefani Almodovar

    Genevieve Cadwalader

    Mark Donofrio

    Megan Grehl

    Rachel Heiligman

    Jeremy KrotzClara Lee

    Sebastian Martin

    Kristin Michael

    Michael Miller

    Zohra Mutabanna

    Benjamin Schneider

    Nicole Thorpe

    David Yim

    Jayon You

    Fall 2008

    Studio Leaders

    Studio Team

    Climate Change:Impacts and Responses in

    the Delaware River Basin

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    This research project would not have been possible without fundingfrom The William Penn Foundation.

    We would like to thank Carol Collier, Amy Shallcross, and Hernan

    Quinodoz of the Delaware River Basin Commission, Mark Alan

    Hughes, Director of Sustainability for the City of Philadelphia, Howard

    Neukrug of the Philadelphia Water Department, Christopher Linn of

    the Delaware Valley Regional Planning Commission, and Professor

    Benjamin Horton from the University of Pennsylvanias Department of

    Earth and Environmental Science. We appreciate your guidance; and

    of course any remaining errors and misjudgments are our own.

    A critical component of this studio was a week long study with

    world-renowned experts in the Netherlands. Dale Morris at the

    Royal Netherlands Embassy in Washington arranged our wonderfully

    informative interviews with experts in the Netherlands including:

    J.W.L. (Hans) ten Hoeve of the Ministry of Spatial Planning and the

    Environment, Hans W. Balfoort and Eric Boessenkool of the Ministry

    of Transport, Public Works and Water Management, Julius Covers and

    Helene Fobler of the Province of South Holland, Daniel Goedbloed,

    Maurits de Hoog, John Jacobs and Arnaud Molenaar of the Public Works

    Department of the City of Rotterdam, and M.A.P. van Haersma Buma

    and K. Huizer of the Deland Water Board. We also greatly appreciate

    the program arranged for us at the Delft University of Technology, and

    particularly for the presentations there by Professors V.J. (Han) Meyer,

    Marcel J.F. Stive, and J.K. Vrijling.

    The City Planning 702 Urban Design Studio hopes that this publication

    can serve as a resource for all agencies and individuals interested in

    the impacts of climate change.

    Acknowledgements

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    6 Mission Statement

    8 Executive Summary

    10 Chapter 1:The Delaware River Basin

    10 Geographic Areas

    12 Forecasting Urbanization

    14 Representative Sites

    16 Chapter 2: Climate Change Threats

    16 Introduction to Climate Change18 Sea Level Rise

    28 Storm Surge

    38 Flood

    48 Combined Hydrologic Threat

    52 Chapter 3: Regional Issues

    52 Introduction

    54 Storm Surge Barrier

    64 Growth Management

    80 Transportation

    90 Industry

    106 Wetlands

    118 Stormwater Management

    128 Water Supply

    Table of Contents

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    134 Chapter 4: Site-Specic Adaptation 134 Introduction

    135 Site Design Dictionary

    138 Lewes, Delaware

    146 Pennsville, New Jersey

    154 Wilmington, Delaware

    162 Philadelphia Airport / Heinz Wildlife Refuge

    172 Philadelphia / Camden Waterfronts

    186 Port Jervis, New York

    194 An Agenda for the Region

    196 Appendices

    Appendix A: State Climate Policies

    Appendix B: Supplementary Maps

    Appendix C: Affected Industrial Land

    Appendix D: Storm Surge Barrier Options

    Appendix E: Affected Land Uses by Site

    Appendix F: Transportation Infrastructure at Risk

    218 Notes

    226 Image Sources

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    This studio examines the escalating threat ofclimate change in the Delaware River Basin inorder to highlight its regional consequencesand inform policy and design interventions.

    By modeling the effects of sea level rise,ooding, and storm surge in the years 2000,2050, and 2100 overlaid with projectedurbanization trends, the studio analyzespotential impacts on land use, infrastructure,and development.

    Recommendations include policy revisions,design guidelines, and physical interventionsthat will protect the economic, cultural, and

    environmental vitality of the region.

    MissionStatement

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    A Present Danger:

    Cities and towns along the Delaware River are already at risk from ood andstorm surge. Storm surges of up to 17 feet from an unlikely but possibleCategory Three hurricane could displace 390,0000 residents, 69,000 jobs,and damage $5.0 billion of residential property. In addition, more than half amillion residents currently live within the 100-year oodplain.

    A Rising Threat:

    The current threat will grow as climate change causes more intenseprecipitation, more frequent and severe storms, and more rapidlyrising sea levels. Sea level rise will permanently inundate land below 0.5meters by 2050 and land below 1.0 meters by 2100. Projected urban growthand expanding hazards could place 1.4 million residents, 147,000 jobs, and$20.4 billion of residential property in the path of sea level rise, ooding, andstorm surge by 2050.

    Differentiating Risk:

    With the highest probability, sea level rise threatens permanent inundationover limited land area in the Rivers tidal reach. Riverine ooding posesa moderate but increasing probability of temporary inundation in valleys

    throughout the Basin. Though relatively improbable, a major storm surgewould cause the greatest damage, overwhelming entire towns, neighborhoods,

    and regional infrastructure.

    Avoiding Risk, Managing Risk:

    Residents, businesses, and cultural and natural resources should be protectedfrom the consequences of climate change. Much of the projected threat couldbe avoided through land use policy that discourages oodplain development,incentivizes relocation from the path of sea level rise, and requires strongerdesign standards in hazardous areas. While insurance will remain crucialto protecting existing development, we also see an increased role for urban

    design, including permanent protective measures.

    Executive Summary

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    Regional Issues Demand Regional Solutions:

    Protecting communities from storm surge through local measures wouldbe impractical. As an alternative to inaction or private risk management,we propose a moveable storm surge barrierthat could shield the entireurbanized region. A strategic retreat from rising sea levels would protectcommunities and enable marsh migrationto offset a projected 32 percentloss in marsh area by 2100. Transportation infrastructure and regionalindustry, both critical to the regional economy,occupy the most vulnerable

    locations. Adaptation will require both physical protection and relocation,with particular attention to preserving evacuation routes (transportation)and remediating inundated brownelds (industry). Climate change may bringa shortage as well as a surplus of water. The combined effects of droughtand sea level rise could compromise public water supplies. Because anincrease in impervious surface compounds the threat of ooding, stormwater

    management will be an essential component of any adaptation strategy.

    Close to Home:

    Looking in detail at six sites both representative and exceptional, we ndcommon themes and local variation. Already at risk from ooding and stormsurge, the Philadelphia Airport - including current runway expansionplans - will be permanently inundated by sea level rise absent intervention.

    Major riverfront redevelopment plans for the Philadelphia, Camden, andWilmington waterfronts target the most vulnerable land for revitalization.These plans must be re-imagined to avoid placing additional population, jobs,and infrastructure in harms way. The continued existence of small riverfrontcommunities like Lewes, DE, Pennsville, NJ, and Port Jervis, NY willdepend on comprehensive adaptation strategies. The challenges of climatechange suggest the need for a conversation on long-term planning and theopportunity for creating new public amenities.

    A Call to Action:

    Our hosts in the Netherlands saw Hurricane Katrina as a reminder of inactionsdisastrous consequences. Yet here in the United States, regions like theDelaware Basin remain unaware of current risks and future threats from

    climate change. To prepare for 2050, we must start building today. And if webuild for 2050, we should plan for 2100, lest our investments face immediate

    obsolescence.

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    The 13,529 square mile Delaware River watershed includesportions of four states: New York, New Jersey, Pennsylvania,and Delaware. From the conuence of the East and Westbranches in Hancock, NY to the mouth of the River at theAtlantic Ocean, the Delaware extends over 300 miles. Severalcities lie along its banks, most notably Wilmington, DE,Philadelphia, PA, and Trenton, NJ. Nearly 8.5 million peoplelived within the boundaries of the Basin in 2000, and thepopulation is projected to grow by 30 percent to 11 million bythe year 2050.1 For the purposes of this study, the Basin isdivided into three sections according to geography, settlementpatterns, and land cover.

    Upper Delaware River BasinThis sparsely populated region extends to the north of theRivers tidal reaches at Trenton, New Jersey. Land coveris dominated by forest, with some agriculture. The UpperDelaware region generates $34 million annually in nature-based tourism. The most notable attraction is the DelawareWater Gap, a dramatic geologic feature where the rivertraverses a ridge in the Appalachian Mountain chain. Othersignicant industries in the Upper Delaware include mining andlogging.

    Urbanized Area

    The Urbanized Area is the most densely populated regionin the Basin. From Trenton, NJ south to Wilmington, DE, itincludes all the major cities situated along the Delaware River.Consequently, the land is primarily developed with a signicantamount devoted to urban infrastructure and industrial uses. Itis home to the Philadelphia International Airport as well as aport complex that generates $3.5 billion in annual revenue andsees 63.5 million metric tons of cargo per year. Several largescale capital projects are planned or in progress in prominentwaterfront locations, including waterfront redevelopment inWilmington, the Philadelphia Navy Yard project, and the centralDelaware riverfront in Philadelphia.

    Lower Estuary

    The Lower Estuary contains the 782 square mile DelawareBay, where the mouth of the river meets the Atlantic Ocean.Historically a more rural region, it has seen increasingdevelopment on both the Delaware and New Jersey sides.Wetlands line the bay, providing important wildlife andvegetation habitat. Low elevations throughout the region meanthat communities are already faced with increasing threatsfrom sea level rise and storm surge.

    Chapter One:Introduction to the

    Delaware River Basin

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    Cities are never static. To evaluate the long-term impact ofclimate change on the region, the studio rst forecast futureurbanization. While multiple scenarios are possible over halfa century, we modeled a conservative projection of existingtrends rather than a prediction of drastically different policiesor spatial patterns.

    Our trend GIS model began with existing urbanized land,2000 population by municipality, and population projectionsby municipality.1 These projections were drawn from a varietyof sources, including the Delaware Valley Regional PlanningCommission. Where municipal projections did not continue to2050, we extended the projection as a linear function. We then

    assumed that, within each municipality, population growthwould be accommodated at the existing gross density.2 Forexample, consider a township with an average of two acres ofdeveloped land for each resident, including houses, businesses,roads, and parking lots. To accommodate a projected growth of2,000 residents, the township would need 4,000 acres of newdevelopment by 2050.

    Using this estimate, we spatially allocated the projectedurban development using a simple algorithm that rankedand selected undeveloped land according to its cost-weighteddistance along the road and rail network to (1) existingdevelopment and (2) existing job centers.3 Using the aboveexample, our future urbanization model would select the

    4,000 undeveloped acres that would be the shortest driveor train ride to existing towns and businesses. The resultingurbanization pattern reects a mature region with modestgrowth: neither wildly sprawling nor radically intensied.

    ForecastingUrbanization

    2

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    To understand the impacts of climate change on real peopleand real places, the studio identied six sites some typical,some exceptional that span the three sections of theDelaware River Basin.

    Lewes, Delaware is a small, beachfront town at the mouth ofthe Delaware Bay. Tied to the sea by history and economy,Lewes faces a dramatically recongured shoreline and thespecter of catastrophic storms.

    Pennsville, New Jerseyis a riverfront community twelve milessouthwest of Wilmington. Located almost entirely belowtwo meters of elevation, Pennsvilles future will hinge on acomprehensive adaptation strategy.

    Like many cities, Wilmington, Delaware is targeting formerly

    industrial riverfront land for redevelopment. Recedingshorelines and ooding threaten to upset these plans andcompound an industrial legacy of soil and water contamination.

    The Philadelphia Airport and the Heinz Wildlife Refuge form aunique complex of transportation and ecological infrastructurein the heart of Philadelphia. Airport expansion plans presenta currently overlooked opportunity to protect the low-lyingairport, expand the existing tidal marsh, and create a newairport city.

    The focus of three major redevelopment plans, ThePhiladelphia and Camden Waterfronts face a critical turningpoint. By addressing climate impacts now, Philadelphia and

    Camden can ensure safe, sustainable riverfront developmentthat will anchor revitalization for the coming century.

    Port Jervis, New Yorkoccupies a narrow valley at theconuence of the Delaware and a major tributary. Longplagued by ooding, Port Jervis and neighboring Matamoras,PA must adapt to a dramatically uctuating Delaware if theyhope to weather climate change in place.

    While climate change poses a threat to these communitiesand others like them, we believe that thoughtful design cansuccessfully manage climate risk while creating new publicamenities. The detailed analysis and adaptation strategiesin Chapter Four reveal the extent of projected hazardsand highlight opportunities for creating strong riverfrontcommunities in an era of uncertainty.

    Representative Sites

    4

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    Introduction to Climate Change

    The Earths climate is changing. Recent years have seen record heat, moreheavy rainstorms, more severe droughts, increased hurricane intensity, andmore frequent tropical storms.1 Decades of climate science conclusivelylink anthropogenic greenhouse gas emissions to increased average globaltemperatures.2 Although debate remains about the rate and the consequences,climate change is indisputable.

    Climate change can be understood as a signicant alteration of long-termweather patterns, measured by indicators such as temperature, rainfall, andwind. A scientic consensus, expressed by the Intergovernmental Panel onClimate Change (IPCC) and reiterated in the United States by the NationalOceanic and Atmospheric Administration (NOAA), suggests the followinggeneral effects:

    increasing average temperatures;

    increasing rates of sea level rise;

    more frequent and severe oods and droughts;

    more frequent and powerful Atlantic hurricanes; and

    northward-shifting tropical storms.

    A Word on Uncertainty

    Modeling these general effects at a regional and local scale involvessubstantial uncertainty. Critical unknown quantities include the exact rate ofglobal temperature increase and sea level rise, the magnitude of increasein precipitation intensity, and the degree of change in hurricane frequency,intensity, and distribution. Yet the rate of currently observed changes suggeststhe need for immediate action. By translating the best available projectionsinto spatially specic scenarios, this research studio offers a starting point for

    policy and design discussions in the Delaware River Basin.

    Chapter 2:Climate Change Threats

    6

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    Current Policy Approaches

    A review of current state-level climate change policy in the Delaware Basinreveals a necessary but limited focus on reducing greenhouse gas emissions.3While emission reductions are critical to long-term sustainability, greenhousegases emitted during the last century and a half of rapid industrial expansionwill continue to inuence future climate changes.4 Therefore, even under themost optimistic scenarios for greenhouse gas reduction, federal, state, andlocal governments must simultaneously consider adaptation to projected

    impacts.

    Introduction to Climate Threat Scenarios

    Although the effects of climate change are many, our analysis focuses on threekey threats to continued prosperity in the Delaware River Basin: sea level rise,storm surge, and ood. By modeling the extent of these threats in the years2000, 2050, and 2100 and then overlaying forecast urbanization patterns, weanalyzed the potential impacts on population, employment, property value,and infrastructure. Responding to this analysis, our recommendations includepolicy revisions, design guidelines, and specic physical interventions thatcould protect the economic, cultural, and environmental vitality of the region.

    In the sections that follow, a briefbackgroundintroduces the science behindeach threat and the studios methodologyfor converting the generalizedpredictions of climate science into spatially specic projections for theDelaware River Basin. Our analysis begins with a general discussion ofndings, and charts showing increased risk for both our trend urbanizationmodel and a regulated scenario where new development is prohibited inaffected areas. On the subsequent pages, aerial perspectives show before-and-after images of the impacts on representative sites. Regional threat mapsappear opposite projections for affected population, jobs, infrastructure,and residential property value, as well as short narratives that blend theseprojections with speculative scenarios of future risk.

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    Background

    Recent attention in the popular media has brought climate change into theAmerican consciousness. Yet the threat posed by one effect of climate change,sea-level rise, continues to emerge. Average global temperature increasesare melting ice caps and glacial shelves at unprecedented rates.1 While theloss of polar bear habitat gains headlines, the direct consequences for coastaland tidal regions remain largely unaddressed. The Delaware River Basin facesacute hazards from sea level rise.

    A complicated phenomenon, sea level rise demands some explanation.Relative sea level rise, dened as the increase over time in the height betweenthe ocean or river oor and the water surface, is the sum of several distinctprocesses. First, melt from glaciers on land adds water volume to existingoceans. Second, water molecules expand with increased temperature, furtherincreasing volume. Together, these two processes constitute eustaticchange,or change in ocean volume. Isostaticchange refers to glacial rebound, or the

    slow raising and lowering of the Earths crust in response to glacial retreatat the end of the last ice age. Fourth, in some parts of the world, the earthstectonic forces affect land position and height and therefore sea levels relativeto the land. Fifth, local conditions, including land subsidence due to localizedsoil and rock composition, impact the height of land in particular regions.2

    Methodology

    The United States government does not predict future sea level rise, but theNational Oceanic and Atmospheric Administration (NOAA) does track historicchange. Over the last century, sea level rise at the Lewes, Delaware stationaveraged 3.2 millimeters per year.3 However, the U.S. Climate Change ScienceProgram, which reports to Congress and the President, reports that rates ofsea level rise are increasing, and will continue to do so in the future.4 For

    specic calculations, the United States defers to the Intergovernmental Panelon Climate Change (IPCC), a consortium of scientists supported by the UnitedNations. IPCC estimates for sea level rise are based on global averages oftemperature increases.5 These increases are directly correlated with, and verylikely caused by, an increase in anthropogenic greenhouse gas emissions.6The IPCC estimates a global rise in relative sea level of 0.18 to 0.59 metersby 2100.7 In a semi-empirical study using the same general methodology asthe IPCC, oceanographer and IPCC contributor Stefan Rahmstorf contests thePanels prediction, suggesting a more extreme sea-level rise of 1.4 meters by2100.8

    The studio examined global predictions and local observations to project sealevel rise in the Delaware River Basin for the years 2050 and 2100. First, westandardized and averaged the global sea-level rise estimates of the IPCC and

    Rahmstorf to generate a eustatic estimate. Second, we incorporated localmeasurements of isostatic changes.9 Third, based on the advice of a sea levelrise expert familiar with local conditions, we assumed the tectonic and localcomponents to be negligible and excluded them from our calculations.10

    Sea Level Rise

    8

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    80,000100,000120,000140,000

    Sea Level Rise - Affected Population

    AffectedPopulation:Regulated

    020,00040,00060,000

    2000 2050 2100

    AffectedPopulation:Trend

    Analysis

    Relative to 2008 mean sea level, the studio projects that sea levels in the

    Delaware River Basin will rise 0.48 meters by 2050 and 1.06 meters by 2100.

    This rate of sea level rise requires a measured and thorough response in thebuilt environment. Unlike other hazards discussed in this report, areas affectedby sea level rise will be permanently or daily inundated. Inundation threatensall land uses: homes, businesses, farms, industry, forests, and marshes. Bypermanently raising water levels, sea level rise compounds both ooding andstorm surge. Additionally, as sea levels rise, the salinity of the Delaware Riverwill increase, threatening drinking water supplies and agricultural production.

    To evaluate the consequences of sea level rise in the Delaware River Basin,the studio conducted a GIS analysis that overlays our sea level rise projectionswith current land use data and the future urbanization model.11 The mapson the following pages depict the Delawares extent at high tide in 2000,

    2050, and 2100. The areas in orange highlight developed land that would bepermanently inundated absent intervention. Using our GIS model, the studioestimated the population, employment, and property values affected by risingsea levels.12

    The chart above identies the population affected by sea level rise in ourfuture urbanization model and a hypothetical, regulated scenario where newdevelopment is barred from areas at risk to climate change threats. Similarsummaries are presented in the following sections on storm surge and ood.Because sea level rise disproportionately affects existing urbanized areas,impacts may be hard to control through growth management. As later sectionsof this report describe, adaptation to sea level rise will require a combinationof physical defense and strategic retreat from receding shorelines.

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    Lewes, Delaware

    Lewes, Delaware after 2100 Sea Level Rise

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    Philadelphia International Airport

    Philadelphia International Airport after 2100 Sea Level Rise

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    In the Delaware estuary, tides change the shape of river and bay daily,ltering through marshes and lapping at the shores of cities and towns. Theshoreline in 2000 reects continuous ux as sea levels rise, beaches erode,and people ll or create water and wetlands.

    Sea Level Rise 2000Baseline

    2

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    A half-meter sea level rise overtakes homes, farms, and wetlands from Lewesto Trenton. Residential neighborhoods in Pennsville and Campbells Field inCamden fall below the Delawares rising waters, while Lewes Beach becomesan island. During a severe drought, rising salinity renders 60 percent ofPhiladelphias water supply undrinkable.

    Population: 56,541

    Jobs: 5,390

    Residential Value: $852,234,989

    Highway: 276 miles

    Rail: 19 miles

    Industrial Land: 1,953 acres (3%)

    Sea Level Rise 2050Effects

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    In Philadelphia, another half-meter of sea level rise inundates riverfrontcondominiums, the Sunoco renery, and the runways of the PhiladelphiaInternational Airport. Lower in the estuary, the Hope Creek nuclear powerplant becomes an island and Bombay Hook National Wildlife Refuge becomesopen water.

    Population: 130,926

    Jobs: 16,600

    Residential Value: $2,951,370,984

    Highway: 372 miles

    Rail: 32 miles

    Industrial Land: 3,663 acres (6%)

    Wetlands: 54,057 acres (32%)

    Sea Level Rise 2100Effects

    6

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    Background

    Storm surge refers to an onshore rush of sea watercaused by severestorms such as hurricanes.1 Wind, low atmospheric pressure, and rainfallcan all contribute to the phenomenon. Storm surge played a central role inthe destruction caused by Hurricane Katrina.2 Although the Delaware RiverBasin has not sustained a direct hit from a hurricane in modern records,geologic evidence indicates that Category Three hurricanes have occurred inthe region.3 In the last decade, the NOAA warned of possible 7-9 foot stormsurges during hurricanes Hannah (2008), Isabel (2003), Jeanne (2003), andFloyd (1999).4 Moreover, the odds of a direct hit are likely to increase withclimate change.5

    Hurricanes that strike the Atlantic coast form in the tropics, taking a counter-clockwise, northward path that can easily penetrate south-facing bays likethe Delaware. The similarly oriented Chesapeake has suffered several hits. 6The turn and bottleneck at Wilmington could create an extremely high surgein this heavily developed area, particularly when combined with riverineooding.7 Storm surge may also be caused by non-tropical storms, such as the

    Halloween Storm (1991) and the Storm of the Century (1993). Also knownas Noreasters, these storms form in the middle latitudes and have coldcores. Noreasters tend to have lower speed winds but larger radii of inuencethan hurricanes.8

    Signicant historic variability in hurricanes and other large storms makes itdifcult to predict future hurricane tracks and intensities. However, projectedclimate changes suggest several effects relevant to the Delaware River Basin:

    Hurricanes and Noreasters will become more intense, with higherwind speeds and heavier precipitation.9Noreasters will likely become more frequent, while the impact of

    climate change on hurricane frequency remains uncertain.10

    Rising sea surface temperatures will move hurricane paths furthernorth, increasing the probability of severe hurricanes in the Mid-Atlantic region.11Sea level rise will increase relative storm surge levels and move thezone of impact further inland.12

    According to the U.S. Global Change Research Program, the aggregate effectof these changes will be more frequent strong storms outside the tropics,with stronger winds and more extreme wave heights.13

    Methodology

    Because the literature on tropical systems is more developed, modeling effortsfocused on storm surges associated with hurricanes. Forecasting hurricanesinvolves great uncertainty, an uncertainty that climate change increases. TheNational Weather Service (NWS) does not calculate the probability of thehypothetical hurricanes that it models, and the literature provides no clearguidance on the magnitude of increase in hurricane frequency and intensityclimate change will produce. Lacking quantied projections, the studioanalyzed a realistic worst-case scenario: a direct hit from a Category Threehurricane.

    Storm Surge

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    0100,000200,000300,000400,000500,000600,000

    2000 2050 2100

    Storm Surge - Affected Population

    AffectedPopulation:Regulated

    AffectedPopulation:Trend

    SLOSH Model Hurricane Impact

    The Sea, Land, and Overland Surge from Hurricane (SLOSH) model wasdeveloped by the NWS and FEMA to predict the depth of storm surge in ageographic location. The SLOSH model considers several critical factors,including astronomical tides at the time of landfall, air pressure and stormintensity, extent of the storm, and storm track. The SLOSH model does not

    include some variables that can signicantly inuence hurricane impacts,including precipitation, river ow at the time of the storm event, andmaximum wind speed sustained. The NWS states a 20 percent margin of erroron the outputs, and suggests that the model is best for dening the maximumpotential surge in a geographic area.14

    Our studio used SLOSH model graphics for Category One through Threehurricanes, graciously provided by the National Weather Service in Mt. Holly,New Jersey. In the Delaware Basin, storm surge is deepest near Wilmingtonand Pennsville, where the river turns from southwest to southeast.15 Buildingon the SLOSH output, the studio used GIS to add the compounding effect ofsea level rise, model the geographic extent of areas ooded by a CategoryThree hurricane, and to estimate the population, employment, and propertyvalues affected.16

    Analysis

    The maps and charts on the following pages illustrate the impact of a CategoryThree Hurricane in 2000, 2050, 2100. It should be noted that the minorchange in geographic extent between time intervals is entirely due to sea levelrise, which effectively adds a half meter to storm surge in 2050 and anotherhalf meter by 2100. The other change, a change in probability, cannot beseen. Although the scenario shown here is unlikely in 2000, the probability willincrease at an unknown rate as climate changes.

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    Pennsville, New Jersey

    Pennsville, New Jersey after 2100 Storm Surge

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    Philadelphia and Camden Waterfronts

    Philadelphia and Camden Waterfronts after 2100 Storm Surge

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    Population: 389,037

    Jobs: 68,546

    Residential Value: $5,021,361,853

    Highway: 604 miles

    Rail: 91 miles

    Industrial Land: 10,414 acres (17%)

    Storm Surge 2000Effects

    Each hurricane season brings storm surge warnings from the National WeatherService and the occasional near miss by a tropical storm or hurricane.In beachfront towns like Lewes, community leaders worry that they areunprepared for this unlikely but catastrophic threat. But upriver, politicalleaders and ordinary citizens continue to associate storm surge with distant

    cities on the Gulf of Mexico.

    2

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    Population: 488,314

    Jobs: 78,961

    Residential Value: $10,097,173,536

    Highway: 646 miles

    Rail: 103 miles

    Industrial Land: 11,371 acres (19%)

    Storm Surge 2050Effects

    More hurricanes track northward each season, and eventually one turnsup the Delaware Bay. A seventeen-foot surge rolls over the entire town ofPennsville and riverfront redevelopments in Wilmington. In the wake of thedestruction, state relief agencies cannot provide enough temporary housingfor the displaced, and many residents leave permanently for regions withless perceived risk. In Philadelphia, a ten-foot surge destroys the new airportterminal and interrupts ights for weeks. Shipping companies move operationsto better-protected ports in New Jersey and Maryland.

    4

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    Population: 565,025

    Jobs: 139,551

    Residential Value: $13,411,852,686

    Highway: 689 miles

    Rail: 124 miles

    Industrial Land: 12,937 acres (22%)

    Storm Surge 2100Effects

    After the cleanup from the 2050 hurricane, the memory fades quickly. Somehomeowners and businesses purchase private insurance to cover hurricanedamage, but when a Category Three hurricane hits the Mid-Atlantic justweeks after a Category Five devastates the Gulf coast, major insurancecompanies go bankrupt and others successfully evade claims in court. Sealevel rise raises storm surge from 2050 levels. A cash-strapped Philadelphiagovernment decides to demolish historic 30th Street Station after the surgedestroys railyards, platforms, and underground tunnels. Across the river fromWilmington, a storage tank breach at the DuPont chemical plant releaseshazardous waste into the Delaware, overwhelming evacuation routes. In thenational media, pundits suggest denying disaster relief to low-lying towns likePennsville, saying they never should have been built in the rst place.

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    Background

    Floods already cause signicant damage in the Delaware River Basin.Consequences of ooding include shoreline erosion, contaminant transport,property damage, and changes in aquifer levels that threaten stored waterand waste. According to estimates from the National Climatic Data Center,reported damages for the Delaware River Basin during a severe 2005 oodtotaled $212 million.1

    Because of climate change, ooding in the next 100 years will not conform topast trends, and oodplains based solely on historical data will underestimatethe extent of ood risk. Although projecting the effects of climate changeon ooding involves great uncertainty, several informed assumptions can bemade. According to the Delaware River Basin Commission, ooding events inthe Delaware Basin will increase in frequency and intensity over the next 100

    years.2

    Sea level rise will permanently raise river levels in the Delawares tidalreaches. At the same time, land use changes unrelated to climate will increasethe amount of impervious surface and runoff. 3

    The oodplain is a probabilistic construct used by the National Flood InsuranceProgram (NFIP), mortgage companies, and other insurance agencies toassess the risk of ooding in a particular area. The Federal EmergencyManagement Agency (FEMA) delineates oodplains according to oodprobabilities calculated from historical data. Most ood insurance policies inthe United States are based on a 100-year oodplain. Just as the 100-yearood has a one percent chance of occurring in a given year, land in the 100-year oodplain has a one in one hundred chance of ooding each year. It isimportant to note that this does not statistically preclude two 100-year oods

    from occurring in consecutive years.4

    Methodology

    To project the oodplain of the future, we began with existing 100-yearoodplain data provided by the DRBC.5 With the baseline established, werelied on the ndings of the Northeast Climate Impacts Assessment forprecipitation projections. The study projects that precipitation intensity,dened as the average amount falling on a day with precipitation, will increase8.5 percent by 2050 and 12.5 percent by 2100.6

    Because GIS does not permit the analysis of dynamic hydrologic ows,our simplied approach assumed that oodplain volume would increaseproportionally with increased precipitation intensity during the 100-yearstorm. Combining elevation data with oodplain maps, the studio estimatedthe volume of existing 100-year oodplains and then increased this volumeat the same rate anticipated for precipitation intensity by 2050 and 2100.Using the new volumes, we then estimated the horizontal extent of projectedoodplains.

    Flood

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    0200,000400,000600,000800,000

    1,000,0001,200,0001,400,0001,600,000

    2000 2050 2100

    Floodplain - Affected Population

    AffectedPopulation:Regulated

    AffectedPopulation:Trend

    This method suffers from several limitations. Existing oodplain maps areoutdated. GIS analysis does not take into account the complex dynamics ofriver ow, assuming that oodplain volume will increase evenly across thewatershed. Finally, the GIS operations used to convert aggregate volumeinto spatial extent tend to overestimate the area of oodplains for smallertributaries and underestimate the oodplain on the main stem. The studiohopes that researchers develop new methods for mapping oodplains thattake into account projected climate change.

    Analysis

    In contrast to sea level rise and storm surge, ooding impacts the entireBasin. By 2050, 1.4 million people could be living in a 100-year oodplain. By2100, this number could increase by another 60,000 if current growth patternscontinue.7 Of the three scenarios examined, the graph shows the largestgap between affected population in the trend urbanization model and theaffected population in a more regulated environment. Urban growth accountsfor 46 percent of the projected increase in affected population to 2050 and44 percent to 2100. Because the projected development has not occurredyet, this component of risk could be avoided through growth managementpolicies. The maps and gures on the following pages show the effect of oodon the urbanized area, where projected growth and expanding oodplainsdramatically increase ood risk. For a full set of maps, see Appendix B.

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    Port Jervis, New York

    Port Jervis, New York after 2100 Flood

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    Wilmington, Delaware

    Wilmington, Delaware after 2100 Flood

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    Population: 534,970

    Jobs: 85,915

    Residential Value: $11,873,574,149

    Highway: 3,626 miles

    Rail: 220 miles

    Industrial Land: 12,519 acres

    Floodplain 2000Effects

    Each year, ooding damages homes, businesses, bridges, and crops acrossthe basin. In Port Jervis, two record oods are still a few years away. Severaltimes each year, heavy rains cause raw sewage to overow into Philadelphiascreeks and rivers. Floodplain residents feel condent that National FloodInsurance will cover losses if waters rise in their neighborhood.

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    Population: 1,451,270

    Jobs: 146,835

    Residential Value: $20,371,137,596

    Highway: 3,965 miles

    Rail: 421 miles

    Industrial Land: 21,834 acres

    Floodplain 2100Effects

    Flooding destroys two-hundred year old townhouses in Philadelphias historicRittenhouse Square neighborhood. Closures of I-95 become a commonoccurrence, costing the region billions. Congress chooses not to reauthorizethe National Flood Insurance Program as annual decits mount. Privateinsurance companies fail to ll the gap, leaving one and a half millionoodplain residents to pay for ood damage out of pocket. Matamoras andPort Jervis have lost seventy-ve percent of their 2000 populations.

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    1,000,000

    1,200,000

    1,400,000

    1,600,000

    1,800,000Combined Scenarios - Affected Population

    AffectedPopulation:Regulated

    0

    200,000

    400,000

    600,000

    800,000

    2000 2050 2100

    AffectedPopulation:Trend

    Combined Hydrologic Threat

    Background

    Sea level rise, storm surge, and ooding present different types of risk, withdifferent probabilities, over varying geographic extents. With the highestprobability, sea level rise threatens permanent inundation over limitedland area in the Rivers tidal reach. Riverine ooding poses a moderate butincreasing probability of temporary inundation in valleys throughout the Basin.While relatively improbable, a major storm surge could cause the greatestdamage, overwhelming entire towns and neighborhoods from Lewes toTrenton.

    Analysis

    Although these risks are distinct, the composite hazard maps on the followingpages suggest the extent of the challenge posed by climate change. Sevenhundred thousand residents are at risk from storm surge and ooding today.1

    By 2100, the combined effects of climate change and urban growth wouldplace an additional 930,000 residents in harms way.2 A combined threatanalysis that considers the differing risk components led directly to thealternative urbanization model detailed in the Growth Management sectionof this report.

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    205Lower Estu

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    205Urbanized A

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    Framework for Regional Policy

    The studios climate threat analysis suggests several general conclusions andprinciples for regional policy:

    Cities and towns along the Delaware River are currently at riskfrom storm surge. This risk will increase as sea levels rise andsevere storms such as hurricanes become more frequent.

    Climate change will increase the intensity and frequency ofextreme rainstorms. Combined with sea level rise, these changesin precipitation will expand the 100-year oodplain.

    Rising sea levels will inundate areas along the Delaware River thatare currently dry land or wetlands.

    Residents, businesses, and cultural and natural resources shouldbe protected from the negative effects of climate change.

    Protection can take the form of physical barriers, insurance, orchanges in land use that would remove development from at-riskareas and allow sea levels to rise unimpeded.

    Choosing the appropriate protection policy raises complex politicaland economic issues. These issues should be addressed throughdetailed analysis and public discussion before projected riskincreases.

    Climate change adaptation strategies should provide economic,

    social, andecological benets.

    This framework guides our approach to six issues of critical regional concern.

    Storm Surge Barrier:

    The Delaware River Basin is unprepared for the increased storm surge riskthat the coming century will bring. Site-specic protections such as dikes andlevees would be impractical and cause unacceptable disruptions to existingcommunities. Therefore, we introduce the idea of a moveable storm surgebarrier, a piece of regional infrastructure that could defend the urbanized reachof the Delaware with minimal impacts to communities, ecology, and shipping.

    Growth Management:

    Our GIS analysis demonstrates that much of the projected climate risk couldbe avoided through land use policy. While physical barriers and insurancewill continue to play an essential role in protecting existing communities, wesuggest that state and local governments pursue a policy of risk avoidanceby limiting development in projected hazard areas. In addition, we identifypractical justications and legal precedents for a strategic retreat fromreceding shorelines.

    Chapter 3:Regional Issues

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    Transportation:

    This critical component of urban infrastructure has historically been placedin the most vulnerable topographic locations, with signicant implicationsfor everyday operations and emergency evacuation plans in a century ofincreased climate risk. We suggest measures to adapt current infrastructureand an emphasis on reducing threats to future investments. Highlighting theconnection between transportation and land use, we also consider the rolethat infrastructure can play in growth management strategies that respond toclimate change.

    Industry:

    Like transportation infrastructure, industry tends to be located in low-lyingareas near the regions rivers and bays. We suggest a balanced strategy of

    protecting river-dependent industry and redirecting river-independent industryto safer locations. As sea levels rise and oods become more frequent, theDelaware Basins vacant industrial lands will pose an increasing environmentalhazard that if properly addressed could become an opportunity for new publicparkland and ecological restoration.

    Wetlands:

    Although climate change poses threats to all ecosystems, the regions tidalmarshes are uniquely susceptible to rising sea levels. Wetlands play anessential role in the regions ecology and economy while shielding communitiesfrom ooding and storm surge. We project marsh loss to 2100, conduct apreliminary suitability analysis for future marsh land, and recommend policiesfor achieving no net loss of wetlands as sea levels rise.

    Water Supply:

    Although the studios analysis focused on excesses of water, climate changewill also lead to more frequent and severe droughts. In combination with risingsea levels, salt water could compromise Philadelphias drinking water supplyand sole-source aquifers throughout the region. We recommend defending keyinfrastructure while pursuing efciency and growth management policies tomaintain aquifers and river ows regionally.

    Stormwater Management:

    Urban development compounds projected increases in precipitation andooding by converting open land to impervious surface. The studio suggestspolicy and design measures to minimize impervious surface and create greenstormwater infrastructure that can reduce ooding and lter runoff whilegreening the urban landscape.

    In the pages that follow, we explore these issues in greater detail. Eachsection begins with background and analysis, followed by generalprinciplesand specic guidelines for action.

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    Storm surge poses a unique threat. Longignored in the Delaware River Basin, fewcommunities are prepared for the havocthat it could bring. Because this potentiallycatastrophic event has a low probability and norecent memory, local governments are unlikelyto undertake the costly and disruptive actionnecessary to defend their residents. Yet theabsence of National Flood Insurance in manyareas prone to storm surge, as well as theunwillingness of private insurance companiesto reimburse storm damage after HurricaneKatrina suggest that insurance may be aninadequate method of managing storm surgerisk.1

    Societies have been dealing with theconsequences of forceful ocean tides forcenturies. Many places have successfully keptstorm surge at bay with dams, dikes, andother physical structures. Yet these structurescan produce signicant environmental impacts:obstructing tides, blocking wildlife movement,and altering the salinity of fragile estuarinesystems.2 In already dense environments suchas Philadelphia and Wilmington, the massivestructures necessary to protect against stormsurge would severely disrupt the urban fabric,displacing homes and businesses. At the same

    time, these distributed protection systems canbe difcult to monitor and maintain.

    Movable storm surge barriers offer a solutionto all three issues. A storm surge barrier is alarge-scale, often movable structure that spansthe entire width of a river. During normalconditions, the barrier allows shipping, tides,and wildlife to move freely. When an extremestorm is forecast, the barrier moves into place,blocking the storm surge and protecting landupstream. As a single, regionally signicantpiece of infrastructure, a storm surge barriercan be closely monitored and maintained.

    Storm SurgeBarrier

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    If properly engineered, a storm surge barrier could protect all upstreamresidents from a Category Three storm surge. Because a storm surge barriercannot protect against riverine ooding, other measures will be needed tomitigate this risk. As with any large public investment, the decision to build astorm surge barrier should be subject to a careful cost-benet analysis and athorough public process. Discussion with experts in the Netherlands suggestedthe following method for evaluating a storm surge barrier: if the cost ofinsuring all affected property exceeds the amortized capital and operatingcosts of a storm surge barrier, the barrier should be built.

    The studio conducted a preliminary site suitability analysis for a storm surgebarrier, selecting a slight narrowing just south of Pennsville, New Jersey. Abarrier at this site would protect the entire urbanized reach of the DelawareRiver, including Wilmington, Philadelphia, Camden, and Trenton. Lower in theestuary, the width of the bay would render barrier construction impractical.

    Proposed Barrier Sites

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    Hydraulic kleppenkering

    Firm: Storcom

    Hydraulic cylinders ap gate

    Schuifdeurkering

    Firm: CHNW

    Straight sliding gates with drawer

    doors

    Pneumatische

    kleppendeurkering

    Firm: BMK

    Flap gate

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    Delaware River Basin Protected by aDisappearing Oscillating Flap-Gate Storm Surge Barrier and Berm System 7 miles South of Pennsville

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    Delaware River Basin Protected by aConcrete Pillar and Steel Door Bridge Storm Surge Barrier at the Delaware Memorial Bridge

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    Section of Proposed Pennsville Barrier with Berm Sytem

    Elevation of Proposed Pennsville Barrier with Berm Sytem

    In addition to the preferred site, the studio identied an alternate site at the currentlocation of the Delaware Memorial Bridge near Wilmington. This location protects lessof the region, but offers a narrower site and potentially lower construction costs.

    Current expertise on storm surge barriers is limited to a few countries, including

    England, the Netherlands, Italy, and Russia all members of the International Networkfor Storm Surge Barrier Managers. Appendix D contains detailed information about thestorm surge barriers used in these four countries. To minimize disruptions to shippingand ecology, we recommend a moveable barrier. Based on our preliminary review ofcurrent technology, we conclude that a disappearing oscillating ap gate would bemost appropriate for the proposed site.

    This barrier type offers several advantages:

    The barrier lies ush with the riverbed when not in use, and should notsignicantly alter the rivers hydrology;

    Ships can pass over the deactivated barrier without disruption;

    The barrier can be built and expanded incrementally;

    Parts of the barrier can be activated without elevating the entire structure; and

    The barrier need not be secured to a receding shoreline.

    Several limitations, however, should be noted:

    This type of barrier requires strong foundational soils on the riverbed,and would require dredging the river to its deepest location at this point,approximately 60 feet;

    This type of barrier will require signicant maintenance, including routineraising and lowering to remove deposited sediment and frequent applicationsof anti-corrosive paint; and

    Construction could temporarily disrupt shipping patterns. 3

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    Delaware Memorial Bridge with Storm Surge Barrier

    Section of Delaware Memorial Bridge with Storm Surge Barrier

    The proposed barrier would consist of 160 individual ap gates spanning theapproximately two-mile width of the Delaware at the selected site. Each individualgate would be 66 feet wide, 15 feet thick, and 99 feet long. The barrier would protectagainst the estimated 17-foot surge generated by a Category Three hurricane in thislocation.4 When a storm surge is forecast, a hydrolytic system on the back of the

    gate would raise each panel to a vertical position. When the surge recedes, the gateswould return to their original position on the riverbed. The barrier could be opened inapproximately 30 minutes.

    Barriers are expensive to construct and even more costly to operate. Based on datafor a similar barrier under construction in Venice, we estimate that a disappearingoscillating ap gate barrier would cost around $3.9 billion to construct andapproximately $18.6 million per year to operate.5 A barrier of this scale would takebetween eight and ten years to complete.6 Using the Venetian barrier as a guide, weestimate that construction would directly generate approximately 1,000 jobs per year.7When fully operational, the barrier would require approximately 150 employees tooperate.8

    While the studio believes the Pennsville site would be most suitable, the DelawareMemorial Bridge in Wilmington, Delaware could offer a lower cost alternative if the

    more comprehensive barrier could not be built. Although a storm surge barrier at theDelaware Memorial Bridge would leave downstream development unprotected, thesite offers two benets: rst, the river is signicantly narrower at the bridge than atthe primary site downstream. Second, although installing the barrier would requirerebuilding the bridge, shipping operations and other uses already navigate andrespond to a similar structure in this location. Attached to a new bridge, moveablegates could be operated independently according to river trafc and oodingconditions. At the shoreline, the barrier would become a ood wall attached to thevertical columns of I-295. Based on costs for the similar Eastern Scheldt Barrier in theNetherlands, we estimate that the proposed barrier would cost around $1.4 billion toconstruct and around $4.8 million per year to operate.9

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    Background and Analysis

    In the next half-century, the population of the Delaware River Basin isprojected to grow by 26 percent.1 Much of that growth will, in the absence ofregulation, occur in areas subject to increased climate risk. By 2100, our trendurbanization model places 1.63 million Basin residents in areas affected bysea level rise, storm surge, and ooding.2 In addition, 147,000 jobs and $20.4billion in residential property values could be affected by the combined threat.3More than half of this impact is avoidable: only 700,000 residents now live inthe projected hazard area.4

    How should the region manage this increased risk? Options include public orprivate insurance, physical structures like levees, seawalls, and storm surgebarriers, and land use policies that regulate development in hazardous areas.As in most of the United States, insurance and private assumption of risk arethe most common responses to climate hazards. We recognize that privaterisk management will remain essential, but propose additional public measuresthat might complement this approach. This section focuses on land use policyrather than the regional and site-specic structures discussed elsewhere in ourreport. Because the nature, probability, and extent of risk varies by hazard, wepropose separate strategies for sea level rise, storm surge, and ooding.

    Sea Level Rise

    Unlike ooding or storm surge, sea level rise threatens gradual, permanentinundation. The permanence of sea level rise demands public policy ratherthan private risk management. The common law of erosion holds that privateproperty rights end at mean high tide.5 Tidelands, which fall between mean lowtide and mean high tide, are usually public domain.6 Although sea level rise

    has only achieved recent recognition, coastal erosion provides a longstandingprecedent. As coastlines erode, or as sea levels rise, private property recedes.7In many states, however, property owners may use bulkheads or ll to preventmovement of the shoreline.8

    Armoring our coastlines may have severe consequences. Bulkheads are costlyand temporary. The zone of sea level rise is also at the highest risk fromooding and storm surge. Allowing private property owners to permanentlyx their property lines not only outs common law, but precludes continuedpublic access and marsh migration. Bulkheading against sea level risethreatens traditional tideland use and ecosystem health. Although thepopularity of beaches has led to regulations that maintain beach access, therelative obscurity of other tidal lands, such as marshes, means less thoroughregulation in the estuary.9

    Therefore, the studio suggests applying the law of erosion to sea levelrise. This principle could be enforced through local land use controls suchas setbacks, combined with regulations prohibiting bulkheads or ll byprivate owners. Setbacks instituted on a rolling basis, that is, relative to themoving line of mean high tide, should not constitute a taking under the FifthAmendment.10 Alternately, tidelands could be preserved through easements ortransfers of development rights, brokered by the public sector or land trusts.As with regulations, these measures may be most effective and least costly ifrolling.

    Growth Management

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    The net effect of these policies would be an unimpeded rise in sea levelsthrough most of the Basin. As shorelines recede, residents and businesseswould gradually relocate. With easements or transfers of development rights,landowners would be reimbursed. Land below mean high tide would becomepublic domain, as it is now. Marshes would migrate to higher ground as theirlower reaches changed to open water. Although we recommend this generalapproach for private land, particularly in undeveloped or sparsely developedareas, we recognize that communities can, and often should, invest inmeasures to protect areas of signicant public or historic value.

    Flood

    Currently, most risk from ooding is managed through the subsidized NationalFlood Insurance Program (NFIP). In all but two counties in the Delaware

    River Basin, residents of the 100year oodplain, as dened by FEMA, arerequired to purchase NFIP insurance. Local oodplain overlay ordinances mayplace other restrictions on oodplain properties, but the signicant amount ofurbanized area already located in the regions oodplains suggests that fewlocalities prohibit oodplain development outright.

    Continued reliance on the oodplain/ood insurance model raises severalissues. As the studio GIS analysis demonstrates, climate and land use changemay signicantly increase future oodplains. If oodplain mapping does notinclude the projected effects of climate change, property owners in hazardousareas may be unable to nd private insurance. At the same time, theavailability of both subsidized insurance and disaster relief in oodplains maylegitimize and encourage development on risky land.

    Given the potential for reduced insurance coverage and the projected increasein ood risk, the studio recommends avoiding new oodplain developmentand incentivizing relocation from oodplains. Climate and land use changeshould be considered in mapping efforts. Any oodplain development that doesproceed should be designed to withstand oodwaters.

    Storm Surge

    The risk of storm surge has been largely overlooked in the Delaware RiverBasin. Damage may be covered under the NFIP, but because affected areaswould likely extend beyond the 100-year oodplain, threatened propertyowners might not hold policies. Katrina demonstrated that insurancecompanies can and will deny holders of homeowners insurance reimbursementfor storm surge damage in the wake of a natural disaster.11 As we discuss in

    the preceding section, the impracticality of local protections for storm surgesuggests a regional solution such as a moveable storm surge barrier.

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    An Alternative Urbanization Model:Building on thetrend urbanization scenario, shown opposite for the lowerestuary, the studio modeled an alternative that embodies apolicy of regional risk avoidance. This scenario reects not arecommended regional plan, but a method for visualizing andquantifying the impact of alternate land use policies.

    Trend 2050With 2100 Threats

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    The alternative urbanization scenario holds all factors constantfrom the trend model, except that:

    No new development occurs in the combined hazard1.area for 2100, including sea level rise, one hundred yearoodplain, and Category Three storm surge.

    Existing homes and businesses in the path of sea level rise2.relocate.

    These two categories are shown in yellow on the map opposite.Gray areas show both current urbanized area outside thezone of sea level rise and trend growth outside all hazardareas: parts of the trend model that remain in the alternativescenario.

    At Risk 2050With 2100 Threats

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    This map shows where redistributed growth from the trendmodel goes in the alternative. Once again, the grays representconstants: current urbanization that remains in both, andareas of future urbanization that both models project. Thisdifference map shows some potential pitfalls of an a narrowlyfocused spatial policy. In some places, bursts of yellowappear around extremely small cores of existing gray as thealternative model redirects high forecast growth to greeneldsites far from threatened towns. Such a challenge points at theneed for a more comprehensive growth management strategy.The alternative urbanization model focuses only on oneobjective directing development to low risk areas ratherthan the multiple goals and constraints that sound land use

    policy must respond to.

    Redistributed 2050With 2100 Threats

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    A composite picture of the alternative scenario appears in thisnal map. Although future climate risk will likely be managedthrough a blend of private insurance, physical structures, andlocal land use policy, this scenario demonstrates the dramaticeffect that either strong state-level policy or widespread localadoption of climate adaptation principles could have on futurerisk. Although apparently radical, it relies on a conservativestrategy of risk avoidance: it requires neither the largeinvestment and constant maintenance of infrastructure northe continued commitment of insurance companies. In thisscenario, population at risk from sea level rise, storm surge,and ooding actually decreases from current levels, ratherthan increasing by the estimated 133 percent in the trendmodel.12 At the same time, by requiring a retreat from risingsea levels, the alternative model maintains a public coastlineand one of the Delaware Basins most crucial ecologicalresources: its tidal wetlands.

    Alternative 2050With 2100 Threats

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    In oodplains, property risk should be privately managed to avoid the problemof moral hazard. Taxpayers should not subsidize development in high-riskareas.

    As insurance companies pull out of high risk areas, municipalities shouldrequire property owners to assume legal risk.

    Residents should be educated about current and future ood risk.

    Although property risk will be managed privately, municipal governmentsshould reduce risk to life and limb by implementing ood warning systems,evacuation plans, and other emergency preparedness measures.

    In the short term, property risk will continue to be managed throughinsurance. Nevertheless, people and businesses should be informed of theincreasing risk, and policymakers should consider the possibility that insurancecompanies may not be willing to guarantee high risk property in the future.

    Manage ood risk privately, butprepare for diminished insurancecoverage.

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    Regional and local governments should avoid new infrastructure investments inoodplains.

    Flood insurance should not be subsidized.

    At the federal level, the income tax deduction for mortgage interest paymentscould be denied for oodplain properties.

    Incentivize relocation fromoodplains.

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    New development in current or projected hazard areas should only take placeif the development is designed to survive a 100-year ood or a Category Threehurricane.

    Design for Risk.

    In local zoning codes, oodplain overlays should prohibit new development,require performance standards, or establish design review.

    Land use regulations in areas at risk of storm surge should be managedthrough overlay zones similar to those used for ooding.

    Mapping these overlay zones will require additional research and establishmentof a standardized regional methodology.

    FEMA oodplains should be remapped to include the effects of climate changeand land use changes on runoff.

    Risk does not end at the edge of the oodplain: policy makers should plan forthe future.

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    Options for regulating development in the path of sea level rise includesetbacks, easements (purchase of development rights), transfer ofdevelopment rights, eminent domain, and fee simple purchase.

    To be effective and enforceable, all development regulations should be pairedwith restrictions on bulkheads, ll, and other methods of articially forestallingsea level rise.

    In the zoning code, a coastal overlay zone could impose setbacks relative tomean high tide on coastal properties. To avoid takings claims, setbacks shouldbe rolling, that is, moving as sea level rises.

    Where zoning codes are absent or local governments are unwilling to regulatecoastal land without compensation, local governments may acquire land,purchase easements, or arrange transfers of development rights.

    Non-prots such as land trusts should also pursue land and development rightacquisition, with particular attention to areas targeted for marsh migration.

    Most states recognize a right to public access in the area between mean hightide and mean low tide. Regulation should preserve access to the tidelands.

    No new development should be allowed in areas of projected sea level rise.Current residents and businesses should be encouraged to relocate.

    Avoid development in the path ofsea level rise.

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    Ensure diverse land uses inrelocated communities.

    Land use policies should, at a minimum, maintain the range of land uses inrelocated areas.

    Adaptation should also be taken as an opportunity to generate public discus-sion about planning and land use.

    Communities in the path of sea level rise should inventory the number andprice of housing units in the affected area, and plan for an equivalent supplyelsewhere in the community.

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    Background

    The Delaware River Basin benets from a highly connected, multimodaltransportation system. This system is vital to the economy and quality oflife in the Basin, and situates the region as a major gateway to the nation.It is therefore important to examine the implications of climate change ontransportation infrastructure, operations, and services.

    An extensive body of research addresses transportations contribution togreenhouse gas emissions and climate change. Yet little attention has beenpaid to the potential impacts of climate change on vital transportationinfrastructure, or the adaptation measures that will be required in response.

    A signicant portion of the regions transportation infrastructure is alreadyat risk. Often built along bays, rivers, and creeks, this infrastructure ishighly prone to ooding.1 As oodplains expand and the chance of a severe

    storm surge increases, so too will the risk to our transportation systems.Moreover, sea level rise threatens permanent inundation to the lowest-lyinginfrastructure. The impacts of climate change on infrastructure include oodedroads, rail lines, subways, and runways; erosion of roadways and bridgesupports; reduced clearance under bridges; and changes in harbor and portfacilities to accommodate higher tides and storm surges.

    Analysis

    All modes of transportation must adapt over the next century in order towithstand climate change. Decision-makers and local ofcials need adequateinformation about the vulnerability of major infrastructure in order to developappropriate adaptation strategies. The studio GIS analysis suggests a rst stepin what should be a thorough and on-going investigation of climate change risk

    and adaptation.

    Equipped with an inventory of the existing highways and rail lines in theDelaware River Basin, the studio overlaid the three climate change threats,highlighting the locations and calculating the amount of infrastructure thatwould be inundated in each scenario. Maps of temporary ooding in 2000and permanent inundation in 2050 appear on the following pages. Onesignicant deciency should be noted: because the studio lacked data onstructures elevated above grade, our calculations may overstate the impactedinfrastructure by an unknown amount.

    The challenge of adaptation should be seen as an opportunity to create amore efcient and balanced regional transportation network. New investmentscan be directed towards a variety of modes, and can be used strategically to

    encourage compact development. Such a policy could accomplish multiplegoals, adapting to climate change while reducing greenhouse gas emissionsand other environmental, social, and economic impacts of transportation.

    Transportation

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    200Rail Lines Subject to Temporary R

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    205Rail Lines Subject to Permanent Inundat

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    200Roadways Subject to Temporary R

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    205Roadways Subject to Permanent Inundati

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    Inventory critical transportation infrastructure to determine when and whereprojected climate changes will affect operations.

    Establish a regional working group focused on sharing best practices andincorporating current knowledge about the impacts of climate changeon infrastructure into planning, design, development, maintenance andoperations.

    Implement a process for better communication among transportationprofessionals, climate scientists, and other relevant professionals.

    Designate a clearinghouse for transportation-relevant climate changeinformation.

    Protect transportation systems.

    Transportation infrastructure is vital to the economy and our quality of life.

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    Modify critical infrastructure susceptible to ooding and erosion.

    Where modication is impractical, relocate critical infrastructure or deviseregional protection measures.

    Establish codes and standards for construction and maintenance that take intoaccount the impacts of climate change.

    Adapt infrastructure.

    Critical transportation infrastructure, including emergency evacuation routes,should be modied or relocated to avoid risks from climate change.

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    In areas that may be temporarily inundated, transportation agencies shouldmap alternate routes, including emergency evacuation routes.

    Coordinate disaster evacuation routes among municipalities.

    Ensure that multiple transportation options are available to vulnerablepopulations.

    Develop monitoring technologies that provide advance warning of failures inmajor transportation facilities.

    Ensure that effective communications systems are in place to rapidly restoretransportation services in the event of failure.

    Prepare for emergencies.

    Climate threats are inherently unpredictable, and physical adaptations cannotrespond to all contingencies.

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    Infrastructure relocation and new transportation investment should beevaluated for the resulting effects on land development.

    Ensure collaboration between transportation and land use planning efforts atthe local, state, and regional levels to foster more integrated decision making.

    Update environmental impact statements used to evaluate transportationprojects to include both climate change mitigation and adaptation measures.

    Ensure that transit promotes compact development with special attentiongiven to mixed-use and pedestrian-oriented design.

    Consider the environmental impactsof infrastructure relocation.Recognize the connection between transportation and land use, and avoidtransportation investments that encourage sprawl.

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    Invest strategically.

    All new transportation investments should take into account the projectedeffects of climate change.

    Avoid transportation investment in vulnerable areas.

    Do not allow transportation investment in the path of sea level rise.

    Although existing transportation infrastructure often lies in a oodplain,transit-oriented development should seek less vulnerable sites.

    Infrastructure relocation should focus on creating a balanced, interconnectedregional transportation system.

    Agencies should avoid investment in hazardous areas, and use infrastructurerelocation as an opportunity to improve the efciency of and access tomultimodal transportation systems.

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    Industry 205Combined Thr

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    The rising Delaware inundates portions of Wilmingtons Portand the DuPont Chemical Compound across the river. A fringeof vacant industrial land, much laden with uncataloguedcontaminants, falls below rising tides from Wilmingtonto Trenton. River-dependent industries must build costlydefenses, while river-independent industries considerrelocation, often to greeneld sites in rural and suburbanmunicipalities.

    Industry 2050Sea Level Rise

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    Industry 2100Sea Level Rise

    The area of inundated land doubles from 2050. The SunocoOil Renery, keystone of the regional petroleum industry,is inundated. Continuous vacant industrial land along theChristina River forms a new band of tidelands.

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    Industry 2050Storm Surge

    The area of inundated land doubles from 2050. The SunocoOil Renery, keystone of the regional petroleum industry,is inundated. Continuous vacant industrial land along theChristina River forms a new band of tidelands.

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    Industry 2050Floodplain

    By 2050, a third of the regions industrial lands would fallwithin the 100-year oodplain, threatening properties activeand vacant, river-dependent and not. In contrast to other landuses, ooding would impact more land than storm surge whilethreatening far more frequent inundation.

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    Heavy Metals, PAH

    Heavy Metals, PAH, PCB

    Heavy Metals, PAH, PCB, Petroleum

    Heavy Metals, PAH, Petroleum

    PAH, PCB

    PCB

    2000 Flood

    2050 Flood

    Wilmington Brownelds

    Brownelds

    The regions industrial legacy presents signicant environmental challenges,including widespread soil and groundwater contamination. The risks posed bysea level rise, storm surge, and ooding further complicate these issues. Todelve deeper into the industrial pollutant problem, the studio conducted a case

    study of Wilmington, Delaware. Long the center of industrial activity in thestate, twenty-four percent, or 1,750 acres, of Wilmingtons usable land areais currently contaminated.4 Common contaminants include polycyclic aromatichydrocarbons (PAHs), polychlorinated biphenyls (PCBs), heavy metals (includ-ing arsenic, mercury and lead), and petroleum compounds.5 Each of thesecontaminants poses dire risks to human and ecological health. Because manycommon contaminants are water soluble, periodic ooding and permanentinundation of brownelds could severely degrade the regions already impairedwaterways. Similar contamination issues may be present on active industrialsites, and should likewise be a priority in climate change adaptation policy.

    Federal, state, and local governments have developed successful incentives,funding, and technical assistance programs to help communities and

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    Olympic Sculpture Park- Seattle, WA

    developers remediate and reuse contaminated lands.6 As part of a climateadaptation strategy, remediation programs should target brownelds at highrisk of inundation and develop a parallel system to address active industriallands in the path of hydrologic threats. A pollutant inventory for the regioncould help identify industrial lands, whether active or abandoned, that shouldbe prioritized for action.

    Low-lying brownelds are often targeted for redevelopment that takesadvantage of their urban waterfront location. Because many of theseredevelopments will be at great risk from sea level rise, storm surge, andooding, communities should consider alternate uses. After remediation, low-lying brownelds offer ideal sites for urban parks, constructed wetlands, andriparian corridors. These amenities provide public space and boost propertyvalues on adjacent private lands without placing additional residents in harmsway. One recent browneld reuse project provides an inspiring example ofthe positive economic, social, and environmental benets that browneldremediation can deliver. Olympic Sculpture Park in Seattle, Washington,converted a nine-acre industrial site into a park that connects the city with itswaterfront and provides a venue for public art.7 The following section outlinesgeneral principles and specic guidelines for adapting industrial land to climatechange.

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    Industry provides regional and local identity as well as employment forriverfront communities.

    Preserve industry.

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    Public safety and environmental health are more important than keeping in-dustry in historical locations.

    Industries relocating from vulnerable areas should remediate contaminatedsoil.

    Public funding and technical assistance should be made available to ease theburden of public relocation plans.

    Browneld programs should target sites in the path of sea level rise for reme-diation.

    Because many industrial contaminants are water soluble, permanentinundation from sea level rise and temporary inundation from ooding posemajor environmental and public health threats.

    Prioritize public health.

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    Keep river-dependent industry inplace.

    Waterfront industry that depends on river access should remain in the currentlocation if prevention of industrial pollution is possible.

    Engineered fortication will be an acceptable adaptation for river-dependentindustry.

    Outside risk areas, riverfront industrial expansion should be accommodated onexisting brownelds rather than on greenelds.

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    Relocate all river-independentindustry from the path of sea levelrise.

    Within risk areas, industrial development on greenelds should be prohibited.

    Waterfront industry that does not depend on river access should be phased outor relocated, and the site should be remediated for conversion to a productive,non-polluting use.

    Within the zone of sea level rise, vacant industrial lands should revert to marshor open water.

    Within other risk areas, vacant industrial lands should be converted to naturalhabitat, public parkland, or other uses exible enough to withstand oodingand storm surge.

    When re-siting industrial uses, air and water quality impacts should be consid-ered. Relocation of air-polluting industries should be discouraged in locationsupwind of urban areas.

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    Background

    Although climate change will impact all ecosystems, this urban planningstudio chose to focus its limited resources on one ecosystem of criticalconcern for climate change in the Delaware River Basin: the marshes thatline the tidal reaches of the River. Tidal marshes are particularly valuable tosociety and uniquely vulnerable to climate change: valuable because theyperform essential ecological services, and vulnerable because they occupy atopographic location directly in the path of sea level rise.

    Wetlands are essential to the regions long-term ecological and economicviability. Wetlands provide critical habitat for local and migratory species,many with commercial value: approximately three-fourths of commercialsh landings in the United States consist of species that depend on estuariesand their wetlands.1 Wetlands prevent coastal erosion and protect coastalsettlements from ooding.2 Finally, wetlands lter and retain nutrients and

    sediment, two key water quality threats in the Delaware estuary.3

    Takentogether, these functions make tidal wetlands one of the most productive anduseful ecosystems on earth. Although placing a price tag on nature is difcult,one prominent study estimates that the value of ecosystem services fromwetlands totals $9,200 per acre per year, compared to $3,600 for forests and$810 for grasslands.4

    As sea levels rise, tidal marshes give way to open water. Marshes do have theability to migrate, or transgress, to higher ground. But this ability dependson human stewardship and the availability of suitable land. The specter ofmarsh loss is particularly poignant given that wetlands offer one of our bestnatural defenses against ooding and storm surge. Tidal marshes may also be

    MHW, 2000

    Low Marsh High Marsh Low Marsh High Marsh

    Low Marsh High Marsh Low Marsh

    Gentle Slope, No Barriers

    Migration Possible

    Steep Slope

    Migration impossible

    MHW, 2000

    MHW, 2050 MHW, 2050

    Wetlands

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    MHW, 2000

    Development

    Migration Impossible

    Levee

    Migration Impossible

    MHW, 2000

    MHW, 2050MHW, 2050

    Low Marsh Hi