23 Dec 2021
 | 23 Dec 2021
Status: a revised version of this preprint is currently under review for the journal NHESS.

Assessment of building damages and adaptation options under extreme flood scenarios in Shanghai

Jiachang Tu, Jiahong Wen, Liang Emlyn Yang, Andrea Reimuth, Stephen S. Young, Min Zhang, Luyang Wang, and Matthias Garschagen

Abstract. Plenty of various measures have been taken to mitigate flood losses in Shanghai over thousands of years, including the construction of sea dikes and floodwalls. However, the combined effects of intensified rainstorms, sea-level rise, land subsidence, and rapid urbanization are exacerbating extreme flood risks and potential flood losses in the fast-developing coastal city. In light of these changes, this article presents an assessment of possible exposure and damage losses of buildings in Shanghai (including residential, commercial, workplace, and industrial buildings). Based on extreme flood scenarios caused by storm surges, precipitation, and fluvial floods, current flood-defence standards will soon be overtaken. Further analyses show that the inundation area could reach 9 %, 16 %, 24 %, and 49 % of Shanghai (excluding the area of islands) under the 1/200, 1/500, 1/1000, and 1/5000-year flooding scenarios, respectively. This study finds, in terms of the total building damage, the 1/5000-year flood scenario damage is more than ten times the 1/200-year flood scenario. Accordingly, the average annual loss (AAL) of residential, commercial, office, and industrial buildings are 13.9, 2.3, 5.3, and 3.9 million USD. Specifically, among the 15 (non-island) districts in Shanghai, Pudong has the highest exposure and AAL at all the four flood scenarios, while the inner city (including seven districts) is also subject to extreme AAL of up to 40 % of its total building values. This study further addresses the possibilities of these extreme flood scenarios, and adaptation options such as: strategic urban planning, advanced building protections, and systematic flood management. Conclusions of the study provide information for scenario-based decision making and cost-benefit analysis for extreme flood risk management in Shanghai and is applicable to other similar coastal megacities.

Jiachang Tu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2021-382', Anonymous Referee #1, 28 Jan 2022
    • AC1: 'Reply on RC1', Jiachang Tu, 26 Apr 2022
  • RC2: 'Comment on nhess-2021-382', Anonymous Referee #2, 04 Jun 2022
    • AC2: 'Reply on RC2', Jiachang Tu, 25 Jul 2022

Jiachang Tu et al.

Jiachang Tu et al.


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Short summary
The study finds the outcome of building damage and its vulnerable pattern under extreme flooding events, which is higher than the present protective level of seawalls and levees in Shanghai, based on the geography-spatial tool and high-resolution information. The study shows that residential building is the most vulnerably building due to the amount of number and asset value. The Wusongkou area has the highlight concerning due to the vulnerable hotspot area for the four types of buildings.