Integrated flood risk assessment for the Mekong Delta through the combined assessment of flood...

Mekong Environmental Symposium | HCMC | 05-07 March 2013 Mekong Environmental Symposium | HCMC | 05-07 March 2013 1

Integrated flood risk assessment for the Mekong Delta

- combined assessment of flood hazard change and social

vulnerability

Heiko Apel1, Matthias Garschagen2, Jose Miguel Delgado1, Nguyen Viet Dung1,3, Vo Van Tuan4, Nguyen Thanh Binh4, Torsten Welle2, Tobias Blätgen2,

Joern Birkmann2, and Bruno Merz1

1 GFZ German Research Centre for Geoscience, Section 5.4 Hydrology, Potsdam, Germany 2 UN University, Institute for Environment and Human Security, Bonn, Germany

3 SIWRR Southern Institute of Water Resources Research, Ho Chi Minh City, Vietnam 4 Can Tho University, Mekong Delta Development Institute (MDI), Can Tho, Vietnam

Folie 2 Mekong Environmental Symposium | HCMC | 05-07 March 2013

Risk Definition

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Hazard- intensity- probability

Vulnerability- exposure

- susceptability

- coping capacity

- adaptation

Risk


Flood Hazard Analysis

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Current hazard

1. Flood frequency analysis for Kratie

2. For selected T generation of synthetic flood hydrographs

3. Hydraulic simulation of inundation of the Mekong Delta

Future hazard

1. Linking flood variability to monsoon variability

2. GCM scenarios for future monsoon variability

3. Estimation of future probabilities of floods



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Current hazard – flood frequency

• Bivariate: flood peak discharge (Q) and flood volume (V)

• Non-stationary: trends in flood regime of the Mekong

• Joint probability Q-V by copula Bivariate Q-V HQ100

Delgado et al. 2010



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Current hazard – hazard maps

• MC sampling of Q-V-pairs from copula

• Scaling of normalized characteristic flood hydrographs

• Hydraulic simulation of inundation



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Current hazard – hazard maps 2009

Median max inundation depth 95%-quantile map 5%-quantile map



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Future hazard – flood frequency 2050

• Exploiting the link of monsoon variability to flood variability non-stationary flood probability estimated by monsoon index

• Joint probability future Q-V by copula

• 14 GCMs, A1B emission scenario

• Sea level rise assumption MONRE: +34 cm in 2050



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Future hazard – hazard maps 2050 Median max depth Difference 2050 - 2009


Flood Exposure

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Flood Exposure

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Vietnam Risk Index: Concept and Architecture

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Indicators of the Vietnam Risk Index – Susceptibility

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Data sources: Population and Housing Census Household Living Standard Survey Statistical Yearbooks

Structure of Vietnam Risk Index


Susceptibility Sub-Index

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Conclusions

Integrative perspectives on hazard and vulnerability are essential to capture overall risk related to current and future flooding

Flood hazard in the Mekong Delta is determined by flood peak and volume need for joint probability assessment

Future flood hazard estimation is possible though climate-flood variability link GCM ensemble prediction of future hazard

Highest susceptibilities not (no longer) in the major flood zones. Are these already the effects of the ‚living with floods‘ policy since 2000?

Vulnerability index can be a helpful tool to capture hot spots of vulnerability and to guide the prioritisation of adaptation action and funding

Hazard modeling in combination with a dynamic element in vulnerability indices allows for the future development not only of hazard scenarios but of integrating risk scenarios focusing on risk pathways

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Thank you very much for your kind attention!

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[email protected] [email protected]

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Supplementary material for Q&A

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Integrated flood risk assessment for the Mekong Delta through the combined assessment of flood...

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