| 08 Oct 2026
An emergency-oriented risk assessment method for typhoon storm surge disasters
Abstract. Typhoon storm surge disaster (TSSD) is one of the most severe marine disasters affecting China's coastal areas, and risk assessment plays a crucial role in disaster prevention and mitigation. Existing studies primarily focus on risk zoning and long-term disaster reduction strategies, whereas risk assessment for an imminent TSSD, which is essential for pre-disaster emergency response, remains insufficient. The main challenges lie in quantifying hazard uncertainty and in representing the multiple dimensions of vulnerability. To address these challenges, this study develops an emergency-oriented risk assessment method for an imminent TSSD that integrates ensemble forecasting into a complete risk assessment framework. For hazard assessment, ensemble forecasting techniques are employed to address hazard uncertainty. A controlled scenario is generated by integrating multi-source forecast data, and perturbed scenarios are derived based on historical forecast errors. These scenarios form an ensemble of 15 scenarios for hydrodynamic simulations, with the mean and maximum water depths characterizing the hazard intensity grade. For vulnerability assessment, land use types and densely populated facilities are selected as two categories of vulnerability. The water depth-loss relative grade relationship for 11 land use types is established, and Point of Interest (POI) density is introduced to represent potential casualty vulnerability. Comprehensive risk is calculated by combining the results of hazard and vulnerability assessments. The method is validated through a case study of the Hato TSSD (2017) in Zhuhai, with the forecast initialization time set at approximately 24 hours before landfall. The proposed method can be re-executed to provide dynamic risk assessment updates as forecast data evolve, providing timely support for emergency decision-making.
The authors use MIKE21 to simulate storm surge hazard, and apply land use based loss functions to calculate economic damage from storms. They also apply this to specific urban centers to develop a proxy for casualties. They then combine these into a mixed metric. The storm surge simulations use variance between simulations from different agencies to estimate an uncertainty in typhoon tracks.
They propose this as a way to quickly estimate spatial risk a day or two before landfall. This is a potentially useful and novel contribution.
My main confusion about the paper is what the various hazard/risk/vulnerability levels I-V mean. These seem to be defined based on water levels, but it is not clear how this relates to risk or vulnerability. Also, it is not clear if these are levels defined here for the first time, or if they are in reference to more common values for hazard levels used elsewhere. This should be clarified. I am also confused by the use of the terms hazard, vulnerability, and risk here. Hazard is water depth, which makes sense. Usually vulnerability will mean the depth-damage function itself, while risk is the integral of hazard x vulnerability (if assuming 100% exposure) over all hazard periods. A clearer definition of each of these terms is needed here in order to understand what the authors are doing.
Line 208. Since you neglect waves, you should justify that by stating in what situations the presence of waves is not important. That will be important to determine where your method is applicable and where it should not be applied.
Table 2. Is this something you made up? Or do the hazard intensities reference an existing scale? This is not clear. Also, is this mean or max water depth?
Fig 5 and Table 4. Does "other construction land" mean "other developed land"?
Table 5. Are these loss grades referenced from somewhere? Or your invention?
Line 376. Would be helpful to have a bit more info about the MIKE21 global tide model. Please at least refer to papers or reports that are publicly available and explain it.
Line 377. Again, state where it is reasonable to neglect waves, and where the result of your simulation does not apply due to this assumption of negligible wave setup and other effects.
Fig 10. There seems to be an offset in the astronomical tide of about 4 hours. Is this due to a time zone problem in the data used in the tidal model? Or is it due to complicated shallow water tide behavior.
Line 439. You state that model performance is consistent with Du, 2020. If you state this, you need to back this up with a figure or data.
Fig 15. The inset map does not appear to show any useful information, as it is identical to the main map. You can delete the inset in this case. Fig 16 also.