Climate vulnerability assessment for urban area in the Netherlands

Transcription

1 Climate vulnerability assessment for urban area in the Netherlands Frans van de Ven, Chris Zevenbergen, Leendert van Bree Deltares / TU Delft, UNESCO-IHE and Netherlands Environmental Assessment Agency 18 maart 2013

2 Climate change and urban areas Research objectives: How vulnerable are Dutch villages and cities for CC? How to reduce this vulnerability by adaptation measures? When to implement these? Who?

3 4.18% Conclusions (1) 9.83% 25.82% Vulnerability Most urban areas in NL are vulnerable for flooding, drought and heat stress Vulnerability is not only result of exposure; also damage sensitivity (susceptibility) and adaptability Only relative vulnerability per theme was assessable Vulnerability varies largely per theme, region and town section No relation found between vulnerability and urban typology 28.32% % Legend Exposure Aggregate Themes 0 ± Kilometers

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5 Conclusions (2) Adaptation Through synergy with urban reconstruction 88 % of our urban areas could be climate resilient by 2060 Many low-cost, low-regret adaptation options. Low-cost climate adaption seems feasible! Adaptation measures depend on local conditions and preferences Effectiveness of measures is location-specific and hard to quantify; research is needed! Climate adaptation is to be part of urban development policy at all levels. Legislation is to be considered

6 CC and urban areas in NL Climate change leads to more exposure of urban areas Sea level rise More and more heavy rainfall More sever droughts River flood peaks Higher temperatures, more evaporation / water demand Dutch cities are vulnerable because: Site conditions (low, no gradient, soft soil) Build centuries ago, with design criteria used in these days Reconstruction only once per year

7 CC vulnerability of the urban system Climate change Urban climate Mitigation Hazard Exposure Sensitivity Vulnerability Adaptation measures Adaptive capacity Urban development Climate Governance Urban Governance KvK voorstel Climate Proof Cities, 2009

8 Vulnerability Vulnerability is result of: Exposure - frequency and degree of Damage sensitivity (susceptibility) Adaptability Exposure: Indicative assessment, using data mining Damage sensitivity Poorly known Adaptability Aging of buildings and infrastructure indicative (?)

9 Theme s investigated Coastal and fluvial flooding Pluvial and groundwater flooding Drought Heat stress For municipalities > inhabitants

10 Coastal and fluvial flooding Hazard Exposure Damage Victims

11 Coastal and fluvial flooding Hazards from: Sea Rivers, lakes, main canals Secundary drainage system Exposure and susceptibility Depth, duration and size of inundations increase 30% of housing areas exposed Most floodprone houses are post WWII; Cultural heritage flood risk free Victims and direct economic damage are assessed; indirect damage hardly known Flood risk Exposure does not increase.. but hazard and damage sensitivity does!

12 Pluvial flooding Amsterdam % flood - affected buildings and infrastructure for 77 mm storm Rotterdam 's-gravenhage Utrecht Eindhoven Almere Tilburg Groningen Nijmegen Haarlem Predicted runoff distributions for a 54mm precipitation event for the Rotterdam region Arnhem Breda Apeldoorn Enschede Amersfoort Zoetermeer Dordrecht Leiden Maastricht Zwolle 0.0% 5.0% % % % % ratio buildings ratio infra 30.0 % Flow accumulations for Delft

13 Pluvial flooding Hazard from More intensive rain storms Exposure and susceptibility NL is flat; no flash floods and limited inundation depths Low-lying urban areas at risk Mostly small damage incidents (e.g. flooded basement, flooded road) No relation with urban typology, except in center zones. Adaptation options Increase retention and storage capacity, in particular in low areas.

14 Groundwater flooding Amount of buildings m Present Situation; Vulnerability to groundwater nuisance drainage dependent intermediate drainage independent before 1800 from 1800 to 1899 from 1900 to 1919 from 1920 to 1939 from 1940 to 1959 from 1960 to 1969 from 1970 to 1979 from 1980 to 1989 from 1990 to 1994 from 1995 to 1999 later then 2000 Building period intermediary drainage dependent drainage independent age and vulnerability of buildings to groundwater nuisance m KNMI'06 W+ scenario; Vulnerability to groundwater nuisance drainage dependent intermediate drainage independent Indicative change in drainage dependency of urban areas (above: current situation; below: situation in the W+ scenario)

15 Groundwater flooding Hazards from: Increase in rainfall and river discharges Exposure and susceptibility Groundwater flooding occurs across NL (high - low, sand clay peat soils) Lowlands with their high groundwater table and subsurface drainage system - and parks are the most vulnerable More urban development in lowlands after WW II Land subsidence aggravates the problem. Adaptation options Plenty no-regret options available. Vulnerability to groundwater nuisance vulnerable not vulnerable Meters

16 Groundwater flooding

17 Drought Hazard from Less rainfall in summer Exposure and susceptibility Low grw level => low soil moisture & enhanced land subsidence Damage to wooden pile foundations 1/3 of pre- 60 buildings! Tree roots adapt to gradual increase of drought Increased impact of salinization and water temperature on water quality Risk Hard to quantify because of lack of data Damage can increase substantially. Adaptation options Water supply required! Vulnerability to drought not substantial strong Meters

18 Heat stress Hazard from Temperature increase + UHI Exposure ans susceptibility Urban Heat Island effects can increase exponentially with urbanisation Urban land use dependent. Industrial zones and business districts perform poorly. Blue and green buffer the UHI effect Elderly are particularly vulnenerable Air conditioning becomes the standard; fossile energy consumption will increase Outdoor activities less attractive Risk Related to density of urban fabric. Susceptibility not yet quantified.

19 Vulnerability 9.83% 4.18% Total risk due to: Coastal and fluvial flooding Pluvial and groundwater flooding Drought Heat stress In- addable 28.32% 31.85% % Result: Urban areas on higher ground limited effect No relation to urban typology All cities have their hotspots Young cities relatively vulnearable, because of their low adaptability ± Legend Exposure Aggregate Themes Kilometers

20 Vulnerability Taking adaptability into account: % 18% 40% 19% 17% % % 13% spatial distribution of the Expected End of Lifespan 11% 61%

21 Adaptive capacity Urban areas transform each years, on average 37% of our urban areas is at it s end of economical life span; these areas will need redevelopment in the next years 88% of our urban areas could be climate resilient by 2060, if synergy with this redevelopment is realised. So: Adaptive capacity is large Start now, not to miss any opportunities!

22 Adaptation measures Adaptability Many measures are no-regret or low-regret

23 In conclusion Adaptive capacity is large ( ) Many low-regret/low-cost measures available Adaptation partly by public, partly by private parties So: Costs of adaptation are limited! We ll miss opportunities if we don t start now! For all details see: Van de Ven, F, E van Nieuwkerk, K. Stone et al ( 2010) Building the Netherlands Climate Proof: urban areas. Report VEB-0003 Deltares and Unesco-IHE, Delft/Utrecht