Global benefits and costs of flood protection. Dr. Philip Ward (Institute for Environmental Studies, VU University Amsterdam)

Transcription

1 Global benefits and costs of flood protection Dr. Philip Ward (Institute for Environmental Studies, VU University Amsterdam)

2 A global framework for future costs and benefits of river flood protection in urban areas Institute for Environmental Studies, VU University Amsterdam Philip Ward, Jeroen Aerts, Wouter Botzen, Paolo Scussolini, Andres Diaz Deltares, Netherlands Hessel Winsemius, Jarl Kind, Jaap Kwadijk World Bank & GFDRR, Washington DC Stephane Hallegatte, Brenden Jongman University of Bristol Paul Bates 2

3 Moving beyond global assessments Dilley et al., World Bank Hotspots Report Ward et al., 2013, ERL; Winsemius et al., 2013, HESS; Jongman et al., 2106; Winsemius et al., 2016 Hirabayashi et al., 2013, Nature Climate Change 3

4 Take home messages 1. Current flood protection already reduces risk by ~91% Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods 4

5 Take home messages 1. Current flood protection already reduces risk by ~91% 2. Globally, benefits of maintaining current risk levels in the future greatly outweigh costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods 5

6 Take home messages 1. Current flood protection already reduces risk by ~91% 2. Globally, benefits of maintaining current risk levels in the future greatly outweigh costs Developing national Flood Risk Management implementation Plan for Nigeria 3. In many regions, benefits of reducing future risk to below current levels far outweighs costs To develop resilience to floods, following recommendations from PDNA after 2012 floods 6

7 Take home messages 1. Current flood protection already reduces risk by ~91% 2. Globally, benefits of maintaining current risk levels in the future greatly outweigh costs Developing national Flood Risk Management implementation Plan for Nigeria 3. In many regions, benefits of reducing future risk to below current levels far outweighs costs To develop resilience to floods, following recommendations from PDNA after 2012 floods 4. Economic feasibility highly spatially heterogeneous 7

8 Research questions 1. What is the current flood risk per state, if flood protection is accounted for? 2. What protection standards are required to keep future flood risk constant? And what are the associated costs and benefits? 3. What protection standards maximize the net present value (NPV) of the investment? 8

9 Current flood risk: GLOFRIS Hazard Inundation depth (50 yr return period) Vulnerability Damage per return period Expected Annual Damage (EAD) Value of assets $ $/yr Exposure Ward et al., Environmental Research Letters, doi: / /8/4/ Winsemius et al., Hydrology and Earth System Sciences, doi: /hess

10 Best-estimate of current flood protection standards FLOPROS database: Scussolini et al., NHESSD 10

11 Reduction in current flood risk: protection v. no protection 11

12 Research questions 1. What is the current flood risk per state, if flood protection is accounted for? 2. What protection standards are required to keep future flood risk constant? And what are the associated costs and benefits? 3. What protection standards maximize the net present value (NPV) of the investment? 12

13 Example: Oregon Best-estimate protection standard Return period = 60 years Current EAD: USD0.9 billion p.a. 13

14 EAD future = EAD current 14

15 EAD future = EAD current 15

16 EAD future = EAD current USD0.9 billion p.a. 16

17 EAD future = EAD current 17

18 Current and future flood protection standards a) RCP2.6/SSP1 ( Sustainability ) b) RCP4.5/SSP2 ( Middle of the Road ) c) RCP6.0/SSP3 ( Fragmented World ) d) RCP8.5/SSP5 ( Fossil-fuel based ) 18

19 Costs and benefits: benefits B = EAD noadapt - EAD adapt Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods 19

20 Costs and benefits: costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods C = (DikeHeight adapt DikeHeight baseline ) X Length of dike required X Cost of dike (USD.km.m) (+ maintenance costs of x% p.a.) 20

21 Costs and benefits: costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods C = (DikeHeight adapt DikeHeight baseline ) X Length of dike required X Cost of dike (USD.km.m) (+ maintenance costs of x% p.a.) 21

22 Costs and benefits: costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods C = (DikeHeight adapt DikeHeight baseline ) X Length of dike required X Cost of dike (USD.km.m) (+ maintenance costs of x% p.a.) 22

23 Costs and benefits: costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods C = (DikeHeight adapt DikeHeight baseline ) X Length of dike required X Cost of dike (USD.km.m) (+ maintenance costs of x% p.a.) 23

24 Costs and benefits: costs Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods C = (DikeHeight adapt DikeHeight baseline ) X Length of dike required X Cost of dike (USD.km.m) (+ maintenance costs of x% p.a.) 24

25 Costs and benefits at global scale Sustainability RCP2.6/SSP1 Maintain constant Expected Annual Damage Middle of the Road RCP4.5/SSP2 Fragmented world RCP6.0/SSP3 Fossil-fuel based RCP8.5/SSP5 Benefits (USD billion p.a.) Costs (USD billion p.a.) B:C ratio Net present value (USD billion) All values in USD 2005 (PPP) Costs and benefits accumulated until 2100 Average results over 5 GCMs 5% discount rate, 1% maintenance costs per year 25

26 Costs and benefits at global scale Sustainability RCP2.6/SSP1 Maintain constant Expected Annual Damage Middle of the Road RCP4.5/SSP2 Fragmented world RCP6.0/SSP3 Fossil-fuel based RCP8.5/SSP5 Benefits (USD billion p.a.) Costs (USD billion p.a.) B:C ratio Net present value (USD billion) All values in USD 2005 (PPP) Costs and benefits accumulated until 2100 Average results over 5 GCMs 5% discount rate, 1% maintenance costs per year 26

27 Costs and benefits at global scale Sustainability RCP2.6/SSP1 Maintain constant Expected Annual Damage Middle of the Road RCP4.5/SSP2 Fragmented world RCP6.0/SSP3 Fossil-fuel based RCP8.5/SSP5 Benefits (USD billion p.a.) Costs (USD billion p.a.) B:C ratio Net present value (USD billion) Maintain constant Expected Annual Damage as a percentage of GDP Benefits (USD billion p.a.) Costs (USD billion p.a.) B:C ratio Net present value (USD billion) All values in USD 2005 (PPP) Costs and benefits accumulated until 2100 Average results over 5 GCMs 5% discount rate, 1% maintenance costs per year 27

28 Benefit:Cost ratios per state a) RCP2.6/SSP1 ( Sustainability ) b) RCP4.5/SSP2 ( Middle of the Road ) c) RCP6.0/SSP3 ( Fragmented world ) d) RCP8.5/SSP5 ( Fossil-fuel based ) 28

29 Research questions 1. What is the current flood risk per state, if flood protection is accounted for? 2. What protection standards are required to keep future flood risk constant? And what are the associated costs and benefits? 3. What protection standards maximize the net present value (NPV) of the investment? 29

30 Return periods of protection with highest NPV a) RCP2.6/SSP1 ( Sustainability ) b) RCP4.5/SSP2 ( Middle of the Road ) c) RCP6.0/SSP3 ( Fragmented world ) d) RCP8.5/SSP5 ( Fossil-fuel based ) 30

31 Next steps 1. Extend to include more adaptation options 2. Include results in the Aqueduct Global Flood Analyzer ( Developing national Flood Risk Management implementation Plan for Nigeria To develop resilience to floods, following recommendations from PDNA after 2012 floods 31

32 Thank you AGU 2018: 2 sessions of interest 1. NH008. Compound and Cascading Events: an Emerging Challenge for Natural Hazard Risk Assessment and Management 2. H062: Global Floods: Forecasting, Monitoring, Risk Assessment, and Socioeconomic Response Deadline for abstracts: Wednesday, 1 August 23:59 EDT. Special Issue NHESS Global and continental scale risk assessment for natural hazards: methods and practice Open for submission Deadline: 31 Jan