Multi-Hazard Risk Assessment of Two Hong Kong Districts
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Research Papers Issue RP0273 Multi-hazard risk assessment of two December 2015 Hong Kong districts Division: Economic analisys of Climate Impacts and Policy (ECIP) By Katie Johnson SUMMARY The assessment of multi-hazard risks in urban areas poses CMCC/ECIP [email protected] particular difficulties due to the different temporal and spatial scales of hazardous events in urban contexts, and the potential interactions between Yaella Depietri Urban Ecology single hazards and between hazards and different socio-economic Lab,Environmental Studies fragilities. Yet this exercise is important, as identifying the spatial distribution Program,The New School,New and concentration of risks in urban areas helps determine where and how York [email protected] preventive and corrective actions can reduce levels of vulnerability and exposure of urban populations. This article presents the results of a and Margaretha Breil CMCC/ECIP GIS-based assessment of present day risks to socio-natural hazards in two [email protected] districts of Hong Kong (PRC) by utilizing indicators to describe the hazards and vulnerabilities. Mapping composite indicators facilitates the communication of complex concepts like vulnerability and multi-hazard risk, allowing for the visual representation of concentrations of hazard intensities and vulnerabilities. Mapping indicators operationalizes the concept of vulnerability at the urban level, and supports the detection of potentially risk prone areas at the sub-urban scale. This approach has the potential of providing city planners and policy makers with visual guidance in focusing The research leading to and prioritizing risk management and adaptation actions with respect to these results has received funding from the current and future risks existing in specific parts of the city, taking into Italian Ministry of account more than one hazard at the time. Under a climate change Education,University and prospective, the assessment of the present day risk is relevant to highlight Research and the Italian Ministry of how the capacity of communities to cope with potentially intensifying Environment,Land and hazards could be strengthened. Sea under the GEMINA project. Keywords: Urban areas,Hazard,Vulnerability,Risk,Climate change,GIS, urban LiDAR data have been provided for use in this adaptation research project by the Hong Kong Civil Urban Adaptation Engineering and Development Department. We would like to thank Francesco Bosello for his revisions and suggestions on a first draft of this paper. CMCC Research Papers INTRODUCTION to heat waves, landslides, and storm surges in two socio-economically diverse districts of Natural hazards in the Asia-Pacific region af- Hong Kong Special Administrative Region of fected 6 billion people and caused over 2 million the People’s Republic of China (herein referred 02 casualties between 1970 and 2014 (ESCAP, to as Hong Kong). It addresses strategies that 2015). These fatalities and the number of per- can improve the knowledge needed for manag- sons affected represent a significant portion of ing and reducing disaster risks in urban areas, the worldwide totals: according to the Eco- with some consideration in the case of future nomic and Social Commission for Asia and the climates. Section 2 provides the state of the Pacific, 56.6 percent of deaths due to disasters art concepts, methods and background infor- and 87.6 percent of people affected by natural mation on risk assessment. Section 3 presents hazards are located in this region. While the the case study areas and the features of several total number of fatalities per disaster has actu- hazards for Hong Kong; section 4, the method- ally decreased over the past several decades, ology used; section 5, the results; section 6, the economic damages have increased (ESCAP, final discussion; and section 7 the conclusions. 2015). Disaster risk reduction activities have helped to lower the number of deaths, yet fac- tors including population growth, development RISK, VULNERABILITY, AND HAZARD: of cities in coastal areas, and climate change CONCEPTS AND METHODS contribute to increased exposure and damages. The term hazard refers to a potentially damag- Since 1980 the number of people exposed to ing physical event, phenomenon or human activ- hydro-meteorological hazards, like floods and ity that may cause the loss of life or injury, prop- storms (cyclones), has increased by 70 percent erty damage, social and economic disruption (UNISDR, 2015c), and this number is likely to or environmental degradation (UNISDR, 2015a, rise with population growth and climate change. p.19 emphasis made by the authors). Risk to Indeed, Asia’s urban population is projected to natural hazards is the combination of the prob- Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici increase from 2.06 billion in 2014 to 3.31 bil- ability or likelihood of a natural hazard to occur lion in 2050 (United Nations and Department and the vulnerability of the system potentially of Economic and Social Affairs, 2014) further affected (UNISDR, 2015a). In contrast to this increasing the number of people exposed to definition provided by the disaster risk reduc- natural hazards. Urban centres in the Asia- tion community, the climate change community Pacific region are often located in geographi- puts less emphasis on the likelihood aspects cally vulnerable areas, and development, es- and defines risk as the result of the interaction pecially of land occupied by the urban poor, of hazard, exposure, and vulnerability (Parry et is increasingly occurring in hazard-prone areas al., 2007). The traditional approach of natu- (ESCAP, 2015). A large portion of Asia’s ur- ral sciences (such as geophysics) to risk has ban population (238 million in 2000) lives less mainly been engineering based with the aim than 10 meters above sea level (Nicholls and of reducing the exposure of potentially affected Small, 2002; McGranahan et al., 2007; Nicholls communities to a seemingly unavoidable event and Cazenave, 2010; IPCC, 2014b), highly ex- (Cardona, 2004). Risk can concretise in a dis- posed to storm surges and sea level rise. aster1 when severe consequences and disrup- This paper proposes an indicator based ap- tion occurs. More recently, the disaster risk proach for the spatial assessment of the risk reduction community modified this perspective Multi-hazard risk assessment of two Hong Kong districts that focused mainly on the characteristics of the the “predisposition of elements at risk (social hazard, including the likelihood of occurrence, and ecological) to suffer harm;” and lack of re- to take increasingly into account the features of silience or coping capacity “determined by lim- the system exposed as key drivers of the en- itations in terms of access to and mobilization 03 tity of potential damages (Bankoff et al. 2004; of the resources of a community or a social- Birkmann, 2006; Wisner et al. 2004). The con- ecological system in responding to an identified cept that the fragilities of the exposed and even- hazard,” (Birkmann et al., 2013). In the long tually impacted social-ecological system also run, the capacity of the system to reduce risk contribute to risk is made evident, for instance, to hazards is called adaptive capacity, which in the case where one hazard unevenly impacts governs “the ability of systems, institutions, hu- distinct parts of the same city due to the socio- mans, and other organisms to adjust to poten- economic and governance failures or dispari- tial damage, to take advantage of opportuni- ties (Collins, 2010).This “vulnerability” perspec- ties, or to respond to consequences”, (Parry et tive in risk reduction originated from social sci- al., 2007). In this sense, adaptive capacity is ences. It takes into account the socio-economic an element modifying vulnerability for instance conditions of people, or their capacity to pre- by enhancing the capacity to cope or by re- vent and cope with a hazard (Cardona, 2004; ducing exposure to climate change impacts in Bankoff et al. 2004; Birkmann, 2006; Wisner the long term. As mentioned, the vulnerability et al. 2004). This perspective has extensively perspective presents hazards not as inevitable framed the concept and analysis of vulnerability events “naturally” affecting socio-ecologic sys- also in the climate change community (Fussel¨ tems, but as the result of the interaction be- and Klein, 2006; IPCC, 2014c; IPCC, 2012). tween the features of the affected system and In this area, vulnerability is generally defined the event. The interaction that takes place be- as the “propensity of exposed elements such tween the natural and the social systems, deter- as physical or capital assets, as well as hu- mining a particular configuration of risk, devel- man beings and their livelihoods, to experience ops not only on the characteristics of the hazard harm and suffer damage and loss when im- itself, but also on the conditions of the social- Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici pacted by single or compound hazard events” ecological system impacted. Some features of (Birkmann et al., 2013). The IPCC Glossary of the transformed social-ecological system can terms2 more simply defines vulnerability as the magnify the impacts of a hazard on the sys- “propensity or predisposition to be adversely tem itself and can therefore be addressed to affected”. It encompasses, further to the char- reduce the risk of damages. Further to haz- acter, magnitude, and rate of climate change ards with a mere natural