Local rain-driven flooding (surface and ground water) Upstream rain-driven flooding (rivers) Tidal or storm surge-driven flooding (coast)

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1 Adapting cities to floods Kristina Hill, PhD University of Virginia School of Architecture Hamburg, Germany What kinds of floods? Local rain-driven flooding (surface and ground water) Upstream rain-driven flooding (rivers) Tidal or storm surge-driven flooding (coast) 1

2 NOAA, 2008 Weather and Climate Extremes in a Changing Climate, Final Report 2

3 Graphic courtesy of Dr. Robert Dolan, UVa How have cities adapted to changing water levels in other regions? 3

4 Three basic strategies for adapting to coastal flooding: 1 build robust barriers around the perimeter, and pump groundwater out as it rises (Rotterdam, London, Tokyo, Taipei) 2 build flood-resilient districts (Hamburg) 3 abandon low-lying districts and allow the frequency of flooding to change the local economy and demographics over time (New Orleans, Jakarta) What needs to be changed in order to adapt? sewage systems (CSO frequency/volume, decentralization) drainage systems (ROW standards, detention/retention capacity) role of tidally-influenced outfalls in each system barriers around low-lying infrastructure and residential areas evacuation routes and plans 4

5 What needs to be changed in order to adapt? sewage systems (CSO frequency/volume, decentralization) drainage systems (ROW standards, detention/retention capacity) role of tidally-influenced outfalls in each system barriers around low-lying infrastructure and residential areas evacuation routes and plans and to adapt successfully: 6 improvements in the quality of urban water discharges 7 mitigation of coastal and riparian habitat losses 8 re-establishment of estuarine seagrass meadows 9 economic and infrastructure investments to maintain a region s competitive status 10 attention to social justice in land use and evacuation plans street tactics 5

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7 SEA (Street Edge Alternatives) Street, Seattle 97% runoff reduction (Rich Horner, UW; Seattle Public Utilities) 7

8 Portland, Oregon 8

9 Ecoducts (land bridges) over a highway connect terrestrial species to a regional protected area at Hammarby-Sjostad. Internally, the stormwater park provides corridors to the water s edge. Standing dead trees are incorporated into the larger park areas. 9

10 green/gray infrastructure hybrid: weirs in pipes as better daylighting strategy-- removes sediments and nutrients, reveals baseflow as amenity in public space; Seattle example, Northgate south lot concept (Seattle Public Utilities). 10

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12 coastal urban adaptations 12

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15 Maeslantkering, Rotterdam; 1997 (storm surge barrier) 15

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20 Hamburg s new Hafencity (Harbor City) district, on the Elbe River 20

21 A historic warehouse district forms the backbone of the Hafencity development. New pedestrian bridges are set higher, to serve as escape routes during floods. 21

22 The Elbphilharmonie, a new symphony hall with luxury units above. Buildings have a hardened 1st story along a wide pedestrian walkway. 22

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25 Raised metal walkways provide alternative circulation, especially during floods. 25

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29 de-centralized urban pattern, each unit semi-independent 29

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31 Initial framework for an urban water plan for New Orleans. PROPOSED edge strategies 31

32 A proposed skirt of submerged floating SAV beds attached to barrier and shoreline. New or re-used pilings as framework for floating inter-tidal and sub-tidal wetlands along dynamic shorelines subject to storm surges and rising sea levels. Proposed for section of former industrial shoreline, Chesapeake Bay watershed. K. Hill and DIRT Studio,

33 What needs to be changed in order to adapt? sewage systems (CSO frequency/volume, decentralization) drainage systems (ROW standards, detention/retention capacity) role of tidally-influenced outfalls in each system barriers around low-lying infrastructure and residential areas evacuation routes and plans and to adapt successfully: 6 improvements in the quality of urban water discharges 7 mitigation of coastal and riparian habitat losses 8 re-establishment of estuarine seagrass meadows 9 economic and infrastructure investments to maintain a region s competitive status 10 attention to social justice in land use and evacuation plans 33

34 Thank you for listening. 34