Multi Hazard Urban Risk Assessment

Abstract

Urban areas are generally characterized by rapid urbanization, urban poverty, haphazard development, inefficient landuse practices, poor governance and deteriorating physical living environment As a result urban people face immense urban risks ranging from ‘every day risk’ to impact of huge ‘disasters’. As urban areas concentrate risks, therefore disasters have greater economical implications. About 1.5% of the total world’s land is estimated to produce about 50% of the world Gross Domestic Product (GDP), which are primarily in urban areas. Thus Disasters cause major disruptions, especially in both low- and middle-income countries, often wiping away decades of development in moments. As per UNDP, “In the first half of 2011 alone, 108 natural disasters occurred, killing over 23 thousand people, affecting nearly 44 million others and causing more than 253 billion US dollars of economic damages”. They further note that “disaster risk is configured over time through a complex interaction between different development processes.” Thus there is a strong need for urban risk management and urban disaster reduction strategies which will help in identifying this complex relationship between disasters and development, which is also primarily influenced by regional characteristics. The mainstreaming of this risk assessment in urban development process will help in achieving resilient and sustainable development. It has been observed that, with complex urban systems and increased urban vulnerabilities, most of the cities in the present context are being subjected to multiple hazards. Thus, the multi hazard phenomenon is a more prominent feature in cities. The mortalities and economic losses due to multiple disasters have been increasing in the last decades due to increased urban vulnerabilities and rapidly degrading ecosystems. As this is a relatively new field, not much research has been taken up on multi hazard risk assessments. As one of the major gaps of multi hazard risk assessment studies, it is noted that not all the combinations of multiple hazards have been taken up for studies till now, and secondly, the selection of indicators of these selected specific hazards are mainly influenced by local conditions of the study area. As a result there are no standardized models and the research is still in its evolution stage. Therefore there is a strong need for in-depth study in this area, taking into consideration, the different combination of multiple hazards, in order to evolve standardised general models of risk assessments. The city of Dehradun, which is the newly formed state capital of Uttarakhand, is geographically located in a multi hazard zone and secondly due to its new status of state capital, rapid urbanization is causing more and more vulnerability, thus this is most appropriately taken up for multi hazard risk assessment. It is primarily impacted by four major hazards, viz., Urban Flood, Urban Fire, Landslides and Earthquake. With respect to Urban Flood risk, the city of Dehradun being located in Doon Valley is mainly affected by water-logging on streets during monsoons, and washing away of river banks by seasonal rivers. The Urban Fire risk is increasingly high due to unplanned urbanization especially with the inflow population after Dehradun city became state capital in the year 2000. Dehradun like other developing cities is no exception to increasing fire incidents. over the years, some major fire accidents iv are primarily noted in high density residential areas, and most commercial areas. Thus an evaluation of the fire risk is necessary to identify those causes which propagate the unnatural risk like urban fire. There is a very high probability of Earthquake risk in Dehradun as the city lies in Zone IV of seismic vulnerability map of India, and it is highly susceptible to the earthquake risk. Though there is some work done to evaluate the earthquake risk, but the major gap is seen in the holistic risk assessment as not all the aspects of risk assessment are considered and evaluated. Himalayas are highly prone to landslides due to earthquake and rainfall induced instability. The northern part of Dehradun due to its location on foothills of Himalayas is highly vulnerable to such landslides and results in slope failure incidences during monsoons/ due to some major earthquake activity. This led to a study on multi hazard urban risk assessment for Dehradun city with the aim to evolve a multi hazard risk assessment model towards Urban Risk Management (URM) for achieving resilient sustainable urban development. This has been achieved through seven objectives which include, evolving methodology and analytical framework for urban risk Assessment; identifying the significant hazards, assessing their risk profile and evaluating the present scenario of urban risks in the selected study area, which is Dehradun. Also other objectives include, generating database for conducting urban vulnerability and multi hazard risk assessment in GIS environment using the ward level data ; thus, identifying risk indicators for conducting assessment at different levels; evaluating Urban Vulnerability Index by integrated analysis of its components’ indices (Social Vulnerability Index, Economic Vulnerability Index, Physical Vulnerability Index, Urban Infrastructure and Services Accessibility Index and Urban Governance Index) and primarily evaluating multi hazard risk index based on integrated analysis of hazards’ risk indices (urban flood risk index, urban fire risk index, earthquake risk index and landslide risk index). Thus final outcome of the thesis resulted in evolution of a model for multi hazard risk assessment, an approach towards Urban Risk Assessment. As next step, an analytical framework is developed for conducting the research. As a part of this, the integrated multi hazard risk assessment integrates the four identified hazards. Thus, a conceptual framework is developed for each of the hazards to evaluate their respective indices from the data collected by a combination of secondary sources, physical survey (primary and visual) and GIS mapping techniques, on elements of risk, hazard and vulnerability. The framework for conducting primary survey includes identifying indicators, framing of survey questionnaires and sampling the population for survey. After data collection, base data preparation is next step where a framework is developed for sorting, documenting the data records for further application of different models. The application of, tools and techniques may vary as applicable in respective situations. The commonly used tools and techniques are the hierarchization of indicators, use of Analytical Hierarchy Process (AHP) for weightage and rank assignment, z- score standardization for normalizing data, along with other statistical tools in MS Excel. Some of the specific tools which are specific to individual hazards' have been discussed in their respective risk assessment sections. v The present study has been carried out in two primary sections- first, assessing the urban vulnerability and arriving at urban vulnerability index and second is accessing multi hazard risk based on integrated risk assessment of four hazards viz., Urban Flooding, Urban Fire, Landslide and Earthquake; to derive multi hazard risk index for 60 wards of the city. The urban vulnerability assessment has been carried out to identify the vulnerable areas of the city, based on their social structure, economic vulnerability, physical (structural) vulnerability, urban services and infrastructure accessibility and governance. The indicator based approach is used to determine the urban vulnerability index. Information on indicators of vulnerability is difficult to obtain and primary data is mainly used. For data collection both - detailed field studies, visual survey is conducted, and/ or census data, have been used in the process. In reality, the lack of sufficient data is a main constraint, especially in absence of any base data, and lack of cooperation at different levels by people. This was observed to be primarily because of safety issues in light of increasing crimes. In the other section, the multi hazard risk assessment is done which is based on the risk assessment of the four identified hazard viz., Urban Flood, Urban Fire, Earthquake, and Landslide. The risk assessment of each of these is based on the concept of PAR, and an indicator based approach is flowed to construct the risk indices viz., Urban Flood Risk Index, Urban Fire Risk Index, Earthquake Risk Index and Landslide risk Index. These indices are integrated to obtain multi hazard risk index by using risk matrix. Results, of the comprehensive evaluation, of weighted components of urban vulnerability, are used to arrive at the Urban Vulnerability Index (UVI) values. Based on these values, it has been concluded, that the wards in the southern and south eastern part of the city are in the range of ‘high’ to ‘very high’ vulnerability. The Urban vulnerability assessment indicates that 12 wards (20.0 %) are at very high risk, 15 wards (25.0 %) are at high risk, 18 wards (30.0 %) are at medium risk and 15 wards (25.0 %) are at low risk. The multi hazard risk assessment is done and Multi Hazard Risk Index (MHRI) is evaluated using RISK MATRIX, where its component indices are weighted, ranked and evaluated based on the two components of Risk Matrix, that is, frequency of occurance and risk serverity. The MHRI is classified into four risk zones- “very high”, “high”, “medium” and “low”. The multi hazard risk assessment indicates that 9 wards (15.0 %) are at very high risk, 13 wards (21.67%) are at high risk, 22 wards (36.67%) are at medium risk and 16 wards (26.66 %) are at low risk. Based on these results, from the two sections- two types of recommendations are made; one set of recommendations based on results of risk assessment, which highlight the policy level interventions needed for urban risk management and the other set of recommendations highlight the interventions required at the risk assessment level. Thus these recommendations allow in improving the multi hazard risk assessment methodology and framework as well as shall become the basis for implementation of (risk measurement based) integrated risk mitigation measures. The delineated spatial zones based on the multi hazard risk assessment results are significant in urban risk management and risk sensitive landuse planning . This research contributes two folds. First it enables us to identify the multi hazard risk zones for the city of Dehradun which is prone to multiple disasters. The identified zones allow framing of vi appropriate mitigation measures and will allow risk sensitive landuse zoning for efficient disaster management and increased urban resilience of the city. Secondly, this study contributes to the research body by development of a methodological model for multi hazard urban risk assessment. This model is developed using indicator based approach and is flexible in terms of addition and removal of number of hazards. This model helps us to identify the linkages and process involved in the multi hazard risk assessment. It represents the holistic process of multi hazard risk assessment for urban areas. There is a tremendous scope for future research in this study, which may be further taken up as smaller studies or an improvement in this study itself.