Abstract: Vulnerability, which quantifies the loss ratio under different hazard intensity, is an important feature of the natural disaster system. However, its estimation is hampered by the lack of loss data of actual cases. To investigate the building content loss due to Typhoon Fitow, we first introduced the concept of flood vulnerability curve and its secondary uncertainty analysis, designed and distributed the questionnaire and collected 386 valid responses, and then analyzed how the loss ratio increased with the water depth based on the survey data. Finally, we fitted eight flood vulnerability curves for building contents using the Logistic function, and quantified their secondary uncertainties using the Beta function. This study reveals that the lower-income households or commercial tenants are more vulnerable to the typhoon disasters. The mean damage ratio of the contents increases with the increasing water depth, which can be generally divided into three stages according to the growth rate. However, the uncertainty within the vulnerability curves arises from many sources. Thus, the secondary uncertainty distribution of the loss ratio which is more dispersed in the second stage varies in different segments of water depth. The correlation between loss ratio and flooding duration is not statistically significant in terms of this questionnaire survey data. The results can effectively describe the flood vulnerability for building contents in Yuyao city of Zhejiang Province so as to provide the input to post-disaster loss assessments and catastrophe modeling applications.

Key words: flood disaster, vulnerability, building content, uncertainty, questionnaire survey