the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Compound flood impact of water level and rainfall during tropical cyclone period in a coastal city: The case of Shanghai
- 1Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, China
- 2School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- 3Department of Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, University of Technology, Delft, Netherlands
- 4Department of Geographical Sciences, University of Maryland, College Park, USA
- 5Deltares, Delft, Netherlands
- 6Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
- 7School of Atmospheric Sciences, and Key Laboratory of Tropical Atmosphere-Ocean System (Ministry of Education), Sun Yat-sen University, Zhuhai, China
- 8Department of Physics, Imperial College London, London, UK
- 1Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, China
- 2School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- 3Department of Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, University of Technology, Delft, Netherlands
- 4Department of Geographical Sciences, University of Maryland, College Park, USA
- 5Deltares, Delft, Netherlands
- 6Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
- 7School of Atmospheric Sciences, and Key Laboratory of Tropical Atmosphere-Ocean System (Ministry of Education), Sun Yat-sen University, Zhuhai, China
- 8Department of Physics, Imperial College London, London, UK
Abstract. Compound flooding is generated when two or more flood drivers occur simultaneously or in close succession. Multiple drivers can amplify each other and lead to greater impacts than when they occur in isolation. A better understanding of the interdependence between flood drivers will facilitate a more accurate assessment of compound flood risk in the coastal regions. This study employed the Delft3D-Flow Flexible Mesh model to simulate the peak coastal water level, consisting of storm surge, astronomical tide, and the relative sea level rise (RSLR) in Shanghai over 1961–2018. It then applies a copula-based methodology to calculate the joint probability of peak water level and rainfall during historical tropical cyclones (TCs) and to calculate the marginal contribution of each driver. The results indicate that the astronomic tide is the leading driver to peak water level, followed by the contribution of storm surge. In a longer term, the RSLR has significantly amplified the peak water level. This framework could be applied to other coastal cities which face the similar constraint of unavailable water level records.
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Hanqing Xu et al.
Status: closed
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RC1: 'Comment on nhess-2022-26', Anonymous Referee #1, 14 Feb 2022
Comment on “Compound flood impact of water level and rainfall during tropical cyclone period in a coastal city: The case of Shanghai” submitted to NHESS by Hanqing Xu et.al
General Comments
This paper is very interesting to work on compound flooding generated when two or more flood drivers occur simultaneously or in close succession. Multiple drivers including socioeconomic can non-lineally amplify each other and to cascade effect of impacts. This paper deals with the peak coastal water level consisting of storm surge and astronomical tide, and as well as the relative sea level rise (RSLR) in Shanghai during 1961-2018. Some novel findings can be presented in the context I recommend to publish this paper in subject to minor correction.
Specific comments:
1, please give more clarification on motivation of writing this paper, i.e. significant importance in Shanghai
2, Please add the discussion in the context to support your findings with references.
- AC1: 'Reply on RC1', Zhan Tian, 16 Mar 2022
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RC2: 'Comment on nhess-2022-26', Anonymous Referee #2, 18 Feb 2022
Review of “Compound flood impact of water level and rainfall during tropical cyclone period in a coastal city: The case of Shanghai” (nhess-2022-26)
This study presents a two-fold, i.e., physics-statistics based framework to understand compound flooding during tropical cyclone period in a coastal metropolis. The physics-based Delft3D-Flow Flexible Mesh was employed to simulate hydrodynamic processes over the coastal city and to simulated storm tides, astronomical tides, relative sea level rise in the adjacent ocean. The copula theory was employed to statistically quantify the interdependence among multiple drivers of compound flooding (here, rainfall and water level). The result of this study sheds light on ocean-land interactions particularly for metropolis, in this case Shanghai.
In my opinion, the framework and the work comprehensively presented here both have the potential for researches and are relevant for applications in a wider sense. From the perspective of climate change, ideally relatively longer investigation period of observations is required. However, this is normally not the case. On the other hand, this study applied the process-based Delft3D for over 50 years simulations, which offers the opportunity to overcome the difficulty in availability of long-term water levels records. Apart from that, such long-term dataset including typhon tracks could be useful in the community for further relevant studies and for saving computational efforts as well.
I would recommend that a minor revision is required to be accepted for publication in Natural Hazards and Earth System Sciences.
General Comments
The storyline of introduction can be improved for enhancing the readability. The significance of this work could be increased by discussing the results in a wider sense.
Specific Comments
L35-38: a relatively long sentence.
L43: what does GDP stand for?
L46-47: could the authors please provide a rough estimate of the damage due to each Typhoon in US dollars? (I saw such numbers in Section 2.1)
L48-49: Please double check the grammar of the sentence.
L106: greater -> higher
L125: costly -> severe
L230: I would expect one or two sentences for describing the results of Figure 5.
L239: What do the authors refer to with the traditional approach?
L254: account -> accounts
- AC2: 'Reply on RC2', Zhan Tian, 16 Mar 2022
Status: closed
-
RC1: 'Comment on nhess-2022-26', Anonymous Referee #1, 14 Feb 2022
Comment on “Compound flood impact of water level and rainfall during tropical cyclone period in a coastal city: The case of Shanghai” submitted to NHESS by Hanqing Xu et.al
General Comments
This paper is very interesting to work on compound flooding generated when two or more flood drivers occur simultaneously or in close succession. Multiple drivers including socioeconomic can non-lineally amplify each other and to cascade effect of impacts. This paper deals with the peak coastal water level consisting of storm surge and astronomical tide, and as well as the relative sea level rise (RSLR) in Shanghai during 1961-2018. Some novel findings can be presented in the context I recommend to publish this paper in subject to minor correction.
Specific comments:
1, please give more clarification on motivation of writing this paper, i.e. significant importance in Shanghai
2, Please add the discussion in the context to support your findings with references.
- AC1: 'Reply on RC1', Zhan Tian, 16 Mar 2022
-
RC2: 'Comment on nhess-2022-26', Anonymous Referee #2, 18 Feb 2022
Review of “Compound flood impact of water level and rainfall during tropical cyclone period in a coastal city: The case of Shanghai” (nhess-2022-26)
This study presents a two-fold, i.e., physics-statistics based framework to understand compound flooding during tropical cyclone period in a coastal metropolis. The physics-based Delft3D-Flow Flexible Mesh was employed to simulate hydrodynamic processes over the coastal city and to simulated storm tides, astronomical tides, relative sea level rise in the adjacent ocean. The copula theory was employed to statistically quantify the interdependence among multiple drivers of compound flooding (here, rainfall and water level). The result of this study sheds light on ocean-land interactions particularly for metropolis, in this case Shanghai.
In my opinion, the framework and the work comprehensively presented here both have the potential for researches and are relevant for applications in a wider sense. From the perspective of climate change, ideally relatively longer investigation period of observations is required. However, this is normally not the case. On the other hand, this study applied the process-based Delft3D for over 50 years simulations, which offers the opportunity to overcome the difficulty in availability of long-term water levels records. Apart from that, such long-term dataset including typhon tracks could be useful in the community for further relevant studies and for saving computational efforts as well.
I would recommend that a minor revision is required to be accepted for publication in Natural Hazards and Earth System Sciences.
General Comments
The storyline of introduction can be improved for enhancing the readability. The significance of this work could be increased by discussing the results in a wider sense.
Specific Comments
L35-38: a relatively long sentence.
L43: what does GDP stand for?
L46-47: could the authors please provide a rough estimate of the damage due to each Typhoon in US dollars? (I saw such numbers in Section 2.1)
L48-49: Please double check the grammar of the sentence.
L106: greater -> higher
L125: costly -> severe
L230: I would expect one or two sentences for describing the results of Figure 5.
L239: What do the authors refer to with the traditional approach?
L254: account -> accounts
- AC2: 'Reply on RC2', Zhan Tian, 16 Mar 2022
Hanqing Xu et al.
Hanqing Xu et al.
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