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© 2023. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Urban flooding is a major challenge for many megacities in low-elevation coastal zones (LECZs), especially in Southeast Asia. In these regions, the effects of environmental stressors overlap with rapid urbanization, which significantly aggravates the hazard potential. Ho Chi Minh City (HCMC) in southern Vietnam is a prime example of this set of problems and therefore a suitable case study to apply the concept of low-regret disaster risk adaptation as defined by the Intergovernmental Panel on Climate Change (IPCC). In order to explore and evaluate potential options of hazard mitigation, a hydro-numerical model was employed to scrutinize the effectiveness of two adaptation strategies: (1) a classic flood protection scheme including a large-scale ring dike as currently constructed in HCMC and (2) the widespread installation of small-scale rainwater detention as envisioned in the framework of the Chinese Sponge City Program (SCP). A third adaptation scenario (3) assesses the combination of both approaches (1) and (2).

From a hydrological point of view, the reduction in various flood intensity proxies that were computed within this study suggests that large-scale flood protection is comparable but slightly more effective than small-scale rainwater storage: for instance, the two adaptation options could reduce the normalized flood severity index (INFS), which is a measure combining flood depth and duration, by 17.9 % and 17.7 %, respectively. The number of flood-prone manufacturing firms that would be protected after adaptation, in turn, is nearly 2 times higher for the ring dike than for the Sponge City approach. However, the numerical results also reveal that both response options can be implemented in parallel, not only without reducing their individual effectiveness but also complementarily with considerable added value. Additionally, from a governance perspective, decentralized rainwater storage conforms ideally to the low-regret paradigm: while the existing large-scale ring dike depends on a binary commitment (to build or not to build), decentralized small- and micro-scale solutions can be implemented gradually (for example through targeted subsidies) and add technical redundancy to the overall system. In the end, both strategies are highly complementary in their spatial and temporal reduction in flood intensity. Local decision-makers may hence specifically seek combined strategies, adding to singular approaches, and design multi-faceted adaptation pathways in order to successfully prepare for a deeply uncertain future.

Details

Title
Low-regret climate change adaptation in coastal megacities – evaluating large-scale flood protection and small-scale rainwater detention measures for Ho Chi Minh City, Vietnam
Author
Scheiber, Leon 1   VIAFID ORCID Logo  ; David, Christoph Gabriel 2   VIAFID ORCID Logo  ; Mazen Hoballah Jalloul 1 ; Visscher, Jan 1 ; Hong Quan Nguyen 3 ; Leitold, Roxana 4 ; Javier Revilla Diez 4   VIAFID ORCID Logo  ; Schlurmann, Torsten 1 

 Ludwig-Franzius-Institute for Hydraulics, Estuarine and Coastal Engineering, Leibniz University Hannover, 30167 Hanover, Germany 
 Division of Hydromechanics, Coastal and Ocean Engineering, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, 38106 Braunschweig, Germany; Junior Research Group “Future Urban Coastlines”, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, 38106 Braunschweig, Germany 
 Institute for Circular Economy Development, Vietnam National University Ho Chi Minh City, 700000 Ho Chi Minh City, Vietnam; Institute for Environment and Resources, Vietnam National University Ho Chi Minh City, 700000 Ho Chi Minh City, Vietnam 
 Institute of Geography, University of Cologne, 50923 Cologne, Germany; Global South Studies Center, University of Cologne, 50923 Cologne, Germany 
Pages
2333-2347
Publication year
2023
Publication date
2023
Publisher
Copernicus GmbH
ISSN
15618633
e-ISSN
16849981
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2829375244
Copyright
© 2023. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.