Building Asset Value Mapping in Support of Flood Risk Assessments: A Case Study of Shanghai, China

Jidong Wu,Mengqi Ye,Xu Wang,Elco Koks

doi:10.3390/su11040971

Jidong Wu, Mengqi Ye + Show 2 more

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https://doi.org/10.3390/su11040971

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Abstract

Exposure is an integral part of any natural disaster risk assessment, and damage to buildings is one of the most important consequence of flood disasters. As such, estimates of the building stock and the values at risk can assist in flood risk management, including determining the damage extent and severity. Unfortunately, little information about building asset value, and especially its spatial distributions, is readily available in most countries. This is certainly true in China, given that the statistical data on building floor area (BFA) is collected by administrative entities (i.e. census level). To bridge the gap between census-level BFA data and geo-coded building asset value data, this article introduces a method for building asset value mapping, using Shanghai as an example. This method consists of a census-level BFA disaggregation (downscaling) by means of a building footprint map extracted from high-resolution remote sensing data, combined with LandScan population density grid data and a financial appraisal of building asset values. Validation with statistical data and field survey data confirms that the method can produce good results, but largely constrained by the resolution of the population density grid used. However, compared with other models with no disaggregation in flood exposure assessment that involves Shanghai, the building asset value mapping method used in this study has a comparative advantage, and it will provide a quick way to produce a building asset value map for regional flood risk assessments. We argue that a sound flood risk assessment should be based on a high-resolution—individual building-based—building asset value map because of the high spatial heterogeneity of flood hazards.

Highlights

IntroductionFlood risk is a combination of hazard (i.e., the probability of occurrence), exposure (i.e., the elements at risk) and vulnerability (i.e., the susceptibility of those elements to damage) [1,2,3]
Flood risk is a combination of hazard, exposure and vulnerability [1,2,3]
Given the existence of a mismatch between high spatial resolution hazard modelling and coarse exposure data in flood risk assessment, this paper proposes a method to disaggregate census building floor area to the regular grid cell level by using ancillary data, and transforms this into a building asset value map via the construction cost per square meter of BFA

Summary

Introduction

Flood risk is a combination of hazard (i.e., the probability of occurrence), exposure (i.e., the elements at risk) and vulnerability (i.e., the susceptibility of those elements to damage) [1,2,3]. Exposure can be defined as the depreciated or replacement value of the tangible physical assets in hazard-prone areas [3,4]. Flood risk under climate change and socioeconomic change is a great challenge for flood risk management [5,6,7,8,9,10]. Considering flood frequency, inundation depth, and depth-damage functions, Oubennaceur and colleagues [12] assessed the expected annual damage to each individual building due to river flooding in a reach of the Richelieu River, Quebec, Canada

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