Coastal vulnerability assessment for Chennai, east coast of India using geospatial techniques

The study area is 56-km coastal zone of Chennai district of the Tamil Nadu state, southeast coast of India. The coastline, which includes tourist resorts, ports, hotels, fishing villages, and towns, has experienced threats from many disasters such as storms, cyclones, floods, tsunami, and erosion. This was one of the worst affected area during 2004 Indian Ocean tsunami and during 2008 Nisha cyclone. The present study aims to develop a Coastal Vulnerability Index for the Chennai coast using eight relative risk variables to know the high and low vulnerable areas, areas of inundation due to future SLR, and land loss due to coastal erosion. Both conventional and remotely sensed data were used and analyzed with the aid of the remote sensing and geographic information system tools. Zones of vulnerability to coastal natural hazards of different magnitude (high, medium, and low) are identified and shown on a map. Coastal regional elevation, near-shore bathymetry, and socio-economic conditions have been considered as additional important variables. This study revealed that 11.01?km of the coastline has low vulnerability, 16.66?km has medium vulnerability, and 27.79?km is highly vulnerable in the study area, showing the majority of coastline is prone to erosion. The map prepared for the Chennai coast can be used by the state and district administration involved in the disaster mitigation and management plan and also as a tool in planning a new facility and for insurance purpose.     

Coastal erosion hazard and vulnerability assessment for southern coastal Tamil Nadu of India by using remote sensing and GIS

The measurement and recording of the height and spatial extent reached by coastal storm surges is fundamental to scientific progress in understanding these phenomena. Such information is required for better prediction and for risk assessment. Model-based evaluation of increasing delta vulnerability, for example, cannot be tested without long-term, consistent, and sustained observation of actual events. Also, storm surges occur within the temporal context of tidal variation, which must first be characterized through observation. Present standard approaches for measuring storm surges are not optimum. Thus, tidal gauges provide information at one point, whereas the heights reached by surges vary spatially. Also, post-surge ground surveys are expensive, laborious, and commonly lack comparison to similar data obtained for previous surges or for high tides. The advent of moderate spatial resolution, high temporal resolution remote sensing initiated by the launch of the two NASA MODIS sensors greatly reduces these constraints. For over a decade, daily coverage of most coastal land areas, though restricted by cloud cover, has systematically captured the maximum extents reached by both high tides and by storm surges. Automated water classification algorithms are now transforming the incoming image data into GIS water boundary files, again at daily or near-daily time steps. This paper provides a retrospective view of sample storm surges as mapped via these sensors and describes: (a) the present, MODIS-based surface water surveillance system, (b) the mapping enhancement to be provided by frequent-repeat, wide-swath satellite radar imaging, and (c) the emerging prospects for routine global surveillance of storm surge events. Such will be necessary if long-term trends are to be recognized, characterized, and understood, along coastal zones now being affected by both increasing subsidence and rising sea level.     

Demystifying vulnerability assessment of agriculture communities in the Himalayas: a systematic review

Agriculture communities in the Himalayas are disproportionately vulnerable due to the emerging challenges from climatic and non-climatic stressors. In this study, we systematically review peer-reviewed literature focused on vulnerability assessment of agriculture communities (n = 26) in the five Himalayan countries (Bhutan, China, India, Nepal, and Pakistan). We examine the yearly distribution, geographical scale, methodological approach, stress in consideration, indicators used, and assessment communication methods of the reviewed papers. Our findings indicate that vulnerability assessment of agriculture communities in the Himalayas is a recent practice, as all of the reviewed articles were published after 2007. About 62% of the assessments were conducted at local (household, community, and village) level, and few assessments at sub-national (19%) and basin (12%) levels. Indicator-based methods using primary quantitative data were most common (54%). Further, 90% of the studies addressed vulnerability to a single stressor with 50% of papers dealing with the vulnerability of agriculture communities to climate change and/or climate variability. From the analysis of the literature, it was found that multi-level, multi-stress, and comprehensive socio-ecological assessments were seldom attempted. Mostly the studies were done in isolated pockets and failed to identify the patterns of vulnerability. We advocate that to holistically understand the vulnerability-creating and differentiating mechanisms in agriculture communities, vulnerability assessment should adopt a multi-level approach by integrating both social and ecological determinants, firstly to identify the hotspots of vulnerability and then to deeply understand the root causes in the identified hotspots through integrated analysis.     

Physical vulnerability assessment of buildings exposed to landslides in India

Natural Hazards - Safe structures are the backbone of human coping capacity towards healthy living that can contribute significantly in reducing risk during hazards. However, due to various natural...     

潮滩脆弱性评估方法研究综述

由于潮滩组成要素不稳定、地理区位特殊以及人为因素的制约,导致潮滩极易受外在和内在因素的影响,发生自然系统脆弱性(包括固有脆弱性和特殊脆弱性)。在总结国内外关于潮滩脆弱性评估方法(诸如综合指数法、层次分析法等综合评估方法以及主成分分析法、高程面积法等单一影响评价法)基础上,根据潮滩脆弱性评估的选择原则,构建了潮滩脆弱性评估指标体系,以期为沿海地区的可持续发展提供理论和技术支撑。     

Coastal vulnerability assessment: a case study on erosion and coastal change along Tuticorin,Gulf of Mannar

Natural Hazards - Assessment of vulnerability is essential for identifying and recognizing the coastal livelihood, socio-economic and ecological security status. However, coastal vulnerability...     

Coastal sensitivity assessment for Thiruvananthapuram,west coast of India

The densely populated coastline of Thiruvananthapuram district of Kerala, along the southwest coast of India, is sensitive to sea surge and severe coastal erosion. The December 2004 Indian Ocean Tsunami had inundated several parts of this coastal zone, indicating nature of sensitivity. The present study is an attempt to develop a coastal sensitivity index (CSI) for Thiruvananthapuram coast within the framework of coastal sediment cells. Seven variables, namely (a) coastal slope, (b) geomorphology, (c) shoreline change, (d) mean sea-level rise, (e) nearshore slope, (f) significant wave height and (g) mean tide range, were adopted in calculation of CSI (the square root of the product of the ranked variables divided by the number of variables). Remote sensing data, topographic maps supported by field work and data from numerical models are used in geographic information system environment to generate CS index for each kilometer segment of this 76-km coastline. This study reveals that 72 % of the Thiruvananthapuram coastline falls in the high sensitive category. This exercise, first of its kind for Kerala coast will be useful for disaster mitigation and management.     

Scales as a challenge for vulnerability assessment

The aim of this paper is to introduce scale as a basic tool for improving the conceptual structure of vulnerability assessments. The terminology useful for vulnerability assessments and the current use of scale issues in theoretical vulnerability frameworks will be discussed briefly. Two case studies working on sub-national and on local level will demonstrate problems as well as benefits resulting from scale implications. Both assessments analyse vulnerability in context to river floods in Germany. In order to develop a spatial comparison and to integrate topics like environment and society, vulnerability assessments need to be aware of scale implications. The main point is that a scale debate on a broader spectrum than just in technical spatial terms is missing in vulnerability and risk conceptualisations so far. Vulnerability assessments and scale are highly intertwined, not only in technical application but also in conceptualisation, which needs more scientific development.     

地下水污染脆弱性评价方法

地下水污染脆弱性是指污染物自顶部含水层以上某一位置到达地下水系统中某一特定位置的趋势和可能性,进一步分为固有脆弱性和特殊脆弱性.地下水污染脆弱性受地下水流系统和地球化学系统的影响和控制.其主要评价方法有主观分级评价法、统计或基于过程的评价法和综合评价法三大类.中国地下水污染脆弱性评价已有很好的工作基础,评价工作中应以地下水系统为单元,以饮用水井、集中供水水源地、区域含水层系统的补给区为重点保护目标,评价方法应综合区域地下水流系统的过程分析和指数评价方法,并利用已有的区域水质资料进行检验,增强评价结论的科学性和可靠性.     

A review of recent urban geographic studies in India

This paper reviews the changing nature of the growing specialized trends of urban geography in India since independence, with a particular emphasis to the 1980s and early 1990s. Urban geography has emerged as a major academic sub-field in India with active researchers at its frontier. The 1980s and early 1990s are characterized by a diversified and growing trend of specialization both in inter-urban and intra-urban research in urban geography. This diversification is most clear and pronounced in intra-urban studies where the emphasis is directed towards socio-cultural aspects of the city. Conversely, inter-urban research is concerned both with analysis of patterns and trends of macro level urbanization and the processes. Although model building is in its infancy, a few static, deterministic, probabilistic and dynamic models have been constructed. There has been severe limitations in the use of computers in India, particularly the large-frame ones, so the researcher there cannot use the large scale data on national level.     

Seismic vulnerability assessment of earthquake-prone mega-city Shillong,India using geophysical mapping and remote sensing

ABSTRACT

The concept of seismic vulnerability is a yard-stick of damage estimation from a probable earthquake considering physical cum social dimension and enables a basis for decision-makers to develop preparedness and mitigation strategies. We aim at vulnerability assessment of the typical urban system of capital city Shillong situated on hilly terrain. High-resolution satellite imagery of Shillong facilitates analysis of building footprints, communication network, and open ground. Different building typologies are identified taking into account the building’s structural configuration assessed through a rapid visual survey of more than 15% of total residential households. Slope map demarcates the landslide-prone area through discrete elevation modelling. A methodology incorporating several parameters e.g. building typology, slope angle, shear wave velocity characteristics, geomorphology, and the number of occupants in correlation with a physical measurement of vulnerability is presented and is applied to estimate the dimension of vulnerability. Additionally, MASW survey indicates lithology up to 30?m deep along with the existence of stiff soil and rocks at different depths whereas resonant frequency is identified to be in the range of 6–8?Hz through H/V ratio. Integrating all, it is observed that more than 60% of Shillong city falls under moderate to higher vulnerability and the rest is less vulnerable.     

Coastal vulnerability assessment based on multi-hazards and bio-geophysical parameters. case study - northwestern coastline of Guinea-Bissau

Natural Hazards - Guinea-Bissau's coasts are considered highly vulnerable to coastal hazards, and this vulnerability is expected to increase under future climate change scenarios. Multi-hazards...     

Social vulnerability indices: a comparative assessment using uncertainty and sensitivity analysis

Social vulnerability indices have emerged over the past decade as quantitative measures of the social dimensions of natural hazards vulnerability. But how reliable are the index rankings? Validation of indices with external reference data has posed a persistent challenge in large part because social vulnerability is multidimensional and not directly observable. This article applies global sensitivity analyses to internally validate the methods used in the most common social vulnerability index designs: deductive, hierarchical, and inductive. Uncertainty analysis is performed to assess the robustness of index ranks when reasonable alternative index configurations are modeled. The hierarchical design was found to be the most accurate, while the inductive model was the most precise. Sensitivity analysis is employed to understand which decisions in the vulnerability index construction process have the greatest influence on the stability of output rankings. The deductive index ranks are found to be the most sensitive to the choice of transformation method, hierarchical models to the selection of weighting scheme, and inductive indices to the indicator set and scale of analysis. Specific recommendations for each stage of index construction are provided so that the next generation of social vulnerability indices can be developed with a greater degree of transparency, robustness, and reliability.     

Contextualizing vulnerability assessment: a support to geo-risk management in central Africa

European Union directives as well as national legislation are placing great emphasis on the inclusion of stakeholder perspectives in the governance of risks from natural hazards. This should help decision makers formulate better policies. However, to date, there is little information on stakeholders’ perspectives with respect to landslide risk governance. This paper addresses the gap by reporting on research in Nocera Inferiore, Italy. The research is based on a documentary analysis, 43 semi-structured interviews and a survey submitted to 373 residents. The political instability, the unfairness of national funding allocation across municipalities and the residents’ lack of knowledge about risk assessment and emergency planning are some of the main barriers to effective risk governance. Moreover, there are divergent, sometimes even opposite, stakeholders’ views on several issues, such as the relevance of illegal development in risky areas. The results highlight the importance of addressing these divergent views and including the plurality of voices as a prerequisite for inclusive risk governance. The research provided essential background information for a participatory process, which was designed to support decisions on landslide risk mitigation measures in Nocera Inferiore (Linnerooth-Bayer et al. this issue). The methodology will be of more general interest to researchers and policymakers intent upon including stakeholder perspectives in natural risk governance.     

地下水污染脆弱性评价方法

地下水污染脆弱性是指污染物自顶部含水层以上某一位置到达地下水系统中某一特定位置的趋势和可能性,进一步分为固有脆弱性和特殊脆弱性。地下水污染脆弱性受地下水流系统和地球化学系统的影响和控制。其主要评价方法有主观分级评价法、统计或基于过程的评价法和综合评价法三大类。中国地下水污染脆弱性评价已有很好的工作基础,评价工作中应以地下水系统为单元,以饮用水井、集中供水水源地、区域含水层系统的补给区为重点保护目标,评价方法应综合区域地下水流系统的过程分析和指数评价方法,并利用已有的区域水质资料进行检验,增强评价结论的科学性和可靠性。     

Seismic vulnerability assessment for Montreal

In Canada, Montreal is the second city with the highest seismic risk. This is due to its relatively high seismic hazard, old infrastructures and high population density. The region is characterised by moderate seismic activity with no recent record of a major earthquake. The lack of historical strong ground motion records for the region contributes to large uncertainties in the estimation of hazards. Among the sources of uncertainty, the attenuation function is the main contributor and its effect on estimates of risks is investigated. Epistemic uncertainty was considered by obtaining damage estimates for three attenuation functions that were developed for Eastern North America. The results indicate that loss estimates are highly sensitive to the choice of the attenuation function and suggest that epistemic uncertainty should be considered both for the definition of the hazard function and in loss estimation methodologies. Seismic loss estimates are performed for a 2% in 50 years seismic threat, which corresponds to the design level earthquake in the national building code of Canada, using HAZUS-MH4 for the Montreal region over 522 census tracts. The study estimated that for the average scenario roughly 5% of the building stock would be damaged with direct economic losses evaluated at 1.4 billion dollars for such a scenario. The maximum number of casualties would result in approximately 500 people being injured or dead at a calculated time of occurrence of 2?pm.