Community-based scenario modelling and disaster risk assessment of urban rainstorm waterlogging

Abstract

Scenario modelling and the risk assessment of natural disasters is one of the hotspots in disaster research. However, up until now, urban natural disaster risk assessments lack common procedures and programmes. This paper selects rainstorm waterlogging as a disaster to research, which is one of the most frequently occurring hazards for most cities in China. As an example, we used a small-scale integrated methodology to assess risks relating to rainstorm waterlogging hazards in the Jing'an District of Shanghai. Based on the basic concept of disaster risk, this paper applies scenario modelling to express the risk of small-scale urban rainstorm waterlogging disasters in different return periods. Through this analysis of vulnerability and exposure, we simulate different disaster scenarios and propose a comprehensive analysis method and procedure for small-scale urban storm waterlogging disaster risk assessments. A grid-based Geographical Information System (GIS) approach, including an urban terrain model, an urban rainfall model and an urban drainage model, was applied to simulate inundation area and depth. Stage-damage curves for residential buildings and contents were then generated by the loss data of waterlogging from field surveys, which were further applied to analyse vulnerability, exposure and loss assessment. Finally, the exceedance probability curve for disaster damage was constructed using the damage of each simulated event and the respective exceedance probabilities. A framework was also developed for coupling the waterlogging risk with the risk planning and management through the exceedance probability curve and annual average waterlogging loss. This is a new exploration for small-scale urban natural disaster scenario simulation and risk assessment.

A review of advances in urban flood risk analysis over China

“…Although several urban rainfallrunoff models have been developed in China since the 1990s, their intrinsic shortcomings, such as poor availability of the models themselves, makes it difficult to apply them in different urban environments Wang et al 2011a). Combined with the distributed hydrologic model, the GIS-based 'water balance' method, which assumes the volume of waterlogging is equivalent to total runoff, has usually been used as a simplified way to determine the maximum inundation extent and depth for small and enclosed urban areas such as Longhu District of Shantou city, Longwan District of Wenzhou city, Jing'an District of Shanghai city and Tianjin Binhai New Area (Zhang 1995;Zhao et al 2004Zhao et al , 2010Yin et al 2011c;Hu et al 2012). Based on field survey, GIS point interpolation methods have occasionally been used to obtain the inundation extent and depth for some urban communities (Yin et al 2009;Li et al 2014).…”

“…Combined with the distributed hydrologic model, the GIS-based 'water balance' method, which assumes the volume of waterlogging is equivalent to total runoff, has usually been used as a simplified way to determine the maximum inundation extent and depth for small and enclosed urban areas such as Longhu District of Shantou city, Longwan District of Wenzhou city, Jing'an District of Shanghai city and Tianjin Binhai New Area (Zhang 1995;Zhao et al 2004Zhao et al , 2010Yin et al 2011c;Hu et al 2012). Based on field survey, GIS point interpolation methods have occasionally been used to obtain the inundation extent and depth for some urban communities (Yin et al 2009;Li et al 2014). A 2-dimensional (2D) hydrodynamic model (Urban Flood Dynamic Simulation Model -UFDSM) has been generated to simulate urban surface flow around 2000, and then it was improved to represent river/sewer flow in 1D and surface flow in 2D on the basis of unsteady flow theory and unstructured mesh (Qiu et al 2000;Xie et al 2005).…”

“…Furthermore, several different methods have been developed for the exposure analysis of urban flooding in China. A GIS-based approach developed by Yin et al (2011c) showed that the spatial exposure information for urban residential buildings can be simply extracted by overlaying the waterlogging extent map with the residential building codes; moreover, buildings' indoor contents exposure could further be obtained by subtracting the building ground level from the water level. In addition, a Waterlogging Exposure Index (WEI) for old-style residences has been designed to make a systematic comparison of waterlogging exposure among different districts in inner-city Shanghai (Shi et al 2010).…”

Effect of urban green space changes on the role of rainwater runoff reduction in Beijing, China

“…The United Nations (2012) reported that flooding has become the most frequent and significant hazard for 633 of the largest cities or urban agglomerations worldwide. Several highly urbanized areas in China, such as Beijing (Gu, Li, Zhou, & Wu, 2013;Li, 2012), Shanghai (Quan et al, 2010;Yin, Yin, Xu, & Wen, 2011), and Guangzhou (Guo & Deng, 2011;Zhang & Ouyang, 2011), have become increasingly prone to flooding in recent years as a result of short-term heavy rains. Thus, immense efforts are focused on improving conventional and innovative stormwater management practices to decrease the runoff volume associated with developed pervious and impervious land covers (Battiata, Collins, Hirschman, & Hoffmann, 2010).…”

Detecting Flood Variations in Shanghai over 1949–2009 with Mann-Kendall Tests and a Newspaper-Based Database

“…Shanghai's urban drainage system has three components: rivers-based drainage system, pipe system, and pumping stations. Up to the present, however, Shanghai's drainage system has only been able to withstand waterlogging by a one-year return period storm-rainfall in the city center and by a half-year return period storm-rainfall in the newly urbanized suburban areas [42,60]. The insufficient drainage system makes urban waterlogging a frequent disaster, which causes widespread damage and disruption to Shanghai [58].…”