基于干旱脆弱性的农户系统体制转换及其影响机制——以榆中县中连川乡为例

通过问卷调查和半结构式访谈获取数据,基于社会-生态系统多体制视角,对农户系统体制及状态进行辨识,并构建农户对干旱的脆弱性指数对其进行评价;采用多元logistic模型识别农户系统体制转换影响因素,并从客观动因、主观动因和决定动因三方面,探讨农户系统体制转换的影响机制。研究表明:①研究区农户系统体制从传统农业体制,向新型农业体制和非农型体制转换。农户由于自身转化力不同,转换结果存在差异。②自然环境和社会经济发展驱动系统体制发生转换,农户期望(教育支出和家庭责任)决定转换方向,农户转变生计方式的能力(行为认知、劳动力比重和社会网络)决定转换程度,在其作用下,农户体制和状态出现差异并最终导致脆弱性分异。     

Fringe explosions: risk and vulnerability in Canada's new in‐between urban landscape

This article argues that a new landscape of urbanization takes shape in Canadian cities. In‐between the old downtowns and the new suburbs of urban Canada, a hitherto underexposed and under‐researched mix of residential, commercial, industrial, educational, agricultural and ecologically protected areas and land uses has become the home and workplace, and increasingly also the playspace of most people in Canada. The article examines this new landscape through the lens of the specific risks and vulnerabilities experienced by its inhabitants and users. Using a propane gas explosion in Toronto in the summer of 2008 as an example, we demonstrate that the ‘in‐between city’ is a space of great complexity, which has grown haphazardly and in a contradictory fashion, where, in contrast to the archetype of inner city and suburb, no clear spatial imaginary has been guiding urban development. This leads to always uncomfortable and sometimes dangerous proximities between various and competing uses and social practices. This is nowhere as clear as it is in the splintered urban infrastructures that service this landscape or use the in‐between city's space to service other adjacent or distant purposes.     

Dry times: hard lessons from the Canadian drought of 2001 and 2002

Droughts are one of the world's most significant natural hazards. They have major impacts on the economy, environment, health and society. In 2001 and 2002, many regions within Canada experienced unprecedented drought conditions, or conditions unseen for at least 100 years in some regions. This article draws upon a national assessment of this drought with particular attention to its implications for the agriculture and water sectors, although some attention is also devoted to other sectors. The study's methodology involves a comprehensive inter-disciplinary, cause–effect integrated framework as a basis to explore the characteristics of drought and the associated biological and physical impacts and socio-economic consequences. Numerous primary and secondary sources of data were used, including public and semi-public sources such as Agriculture and Agri-Food Canada, Environment Canada, Statistics Canada, Crop Insurance Corporations and provincial governments, as well as phone interviews, focus groups, print media surveys and economic modelling. Evidence indicates that the risk of drought is increasing as demands for food and water relentlessly climb and the manifestations of climate change become more apparent. The key to better dealing with drought lies in taking the steps necessary to enhance our adaptive capacity and decrease vulnerability.     

ANTAEUS Project for the Regional Vulnerability Assessment of the Current Building Stock in Historical Centers

This article presents a methodology for the seismic vulnerability assessment of current buildings, suitable for the study of historical centers at the regional scale. The applicability is demonstrated with reference to four case studies: the historical center of the city of Foggia (Italy) and three other small towns of this province, for a total of 4519 housing units. Field data were collected by several teams of technicians by means of a survey form, provided in electronic format. The subsequent data processing and drawing of vulnerability maps was performed using geographical information system (GIS) technology. The collected data were used also for the validation of the algorithm, by comparing the results with those of the methodology used by the Gruppo Nazionale per la Difesa dai Terremoti (GNDT [Italian National Group for Defense Against Earthquakes]), which is widely adopted in Italy. The results of the research study and the application showed some critical points, related to the poor nature of the information collected and to the reliability of the final results. These issues are analyzed and discussed, proposing a strategy for improving the methodology.     

Seismic Vulnerability Assessment of the Urban Building Environment in Nablus,Palestine

ABSTRACT

This article describes a specifically developed framework to produce a seismic physical vulnerability model of residential buildings in Nablus (Palestine) within the European project SASPARM2.0. Based on the structural taxonomy of the territory, two different forms were defined to collect geometrical and structural data of buildings by different stakeholders (citizens and practitioners). This data was then employed to produce fragility curves using the mechanics-based procedure SP-BELA. To estimate seismic risk, the developed fragility model was combined with a hazard curve for the corresponding location. The described procedure is implemented in a WebGIS platform that allows to georeference and assess the surveyed buildings and define retrofitting strategies. Finally, the article carries out a comparison between the fragility curves of buildings in Nablus and the ones calculated for similar building typologies within a UNDP Jordan project aiming at the integrated risk assessment in Wadi Musa and surroundings.     

New Indices for the Existing City-Centers Streets Network Reliability and Availability Assessment in Earthquake Emergency

During earthquake emergencies in existing city-centers, streets network permits inhabitants to reach safe areas, and rescuers to access damaged zones and help population. However, the network can suffer from blocks due to debris of collapsed or heavily damaged buildings. Understanding urban fabric modifications and classifying elements vulnerability are fundamental steps while dealing with risk-assessment and risk-reduction strategies. This article offers a first quick approach for assessing seismic vulnerability of paths network by considering interferences with building heritage damages. Quick data about existing urban fabric (e.g., buildings typology; streets and buildings geometries) are combined for developing new vulnerability indices for streets network. The earthquake macroseismic intensity is introduced for evaluating probable street blockages and summarizing the overall rating of risks in critical network locations, thus intensity that is not included in other current quick methods for streets-building interference is here taken into account. Risk-reduction strategies based on the proposed indices could minimize the interventions on architectural heritage, maximizing the safety of evacuees. These new indices could be combined with traditional assessment of buildings vulnerability, and evaluations on pedestrians’ and vehicles evacuation flows, for evaluating management strategies.     

Assessing Seismic Social Vulnerability in Urban Centers — the Case-Study of Nablus,Palestine

ABSTRACT

Seismic risk depends on three factors: seismic hazard, exposure of assets and communities, and vulnerability—physical and social. Whereas hazard and exposure are harder to act upon, vulnerability can be significantly reduced, if properly characterized for each asset, population, or society in general. This article assesses the social vulnerability and resilience level of the city of Nablus, an important urban center in Palestine. The region, considerably exposed to seismic hazard, features, from the in-built view point, very recent or very old historical buildings, without seismic design provisions. On the socio-economic side, the well-known political conflicts and societal challenges are key vulnerability factors. The method employed was based on Social Vulnerability Indicators (SoVI) extracted from census data, integrated with the more recent SCORECARD approach, which was applied to the urban community of Nablus. The goal was both to obtain an overall vulnerability score for the city and to characterize internal differences among its main areas, connected to its historical urban expansion and patterns. The results show that both physical and social vulnerability can be related and that the city development patterns can mirror the relative social vulnerability.     

Seismic behavior of two Portuguese adobe buildings: Part I - in-plane cyclic testing of a full-scale adobe wall

This article addresses the laboratory testing of a full-scale double-T shaped adobe wall, under in-plane horizontal cyclic loading of increasing amplitude, with the aim of contributing to the understanding of the seismic behavior of adobe structures. The wall was built with lime adobes taken from an existing building and mortar with a traditional composition. The behavior of the wall was assessed in terms of: shear stress versus horizontal drift and moment versus rotation relationships; maximum lateral strength; drift and rotation at peak stress; evolution of stiffness, lateral displacements, dissipated energy, and natural frequency; and damage pattern. The wall exhibited brittle behavior and in-plane strength corresponding to 56% of the vertical load. Cracking was observed with an X-shaped pattern whereas no sliding occurred at its base. This research supported the subsequent development of a repair and retrofit solution and also of numerical models to simulate the seismic behavior of two adobe buildings.     

Measuring park visitation vulnerability to climate extremes in U.S. Rockies National Parks tourism

ABSTRACT

Changes in temperature and precipitation can affect tourist experiences. This study examines how summer park visitation has changed in response to temperature and precipitation extremes. The study goals were two-fold. The first is to introduce a framework and the second is to test it in a pilot region with four mountainous National Parks. The framework is designed to compare the vulnerability of seasonal park visitation to shifts in a combined indicator of temperature and precipitation. It uniquely considers needed measurements, and the data required to conduct an analysis. The second goal is to test it in four destinations in the U.S. Northern Rockies, including Glacier, Yellowstone, Grand Teton, and Rocky Mountain National Parks. The preliminary test reveals outlier cases of visitation under wet and dry extremes. The analysis connects time series climate and visitation data for the peak summer season from 1991–2012. Outlier analysis illustrates more change in extremely dry conditions, with four out of the six dry-year outliers resulting in a visitation decline. Whether this decline in park tourism is attributable to climate features, economic factors, or conscious management decisions, these drops have significant economic impacts: estimates of changes in visitor spending during dry years are between roughly 9 and 90 million USD. These differences may be connected to the popular activities in each park, and the extent they are dependent on weather conditions. This framework can be used to test the relationship between climate and tourism visitation in other regions, in various seasons and time frames. The work may inform the tourist sector in adjusting and planning for a range of conditions. We discuss opportunities and conclude with additional needs for understanding the mechanisms behind risk in mountain park tourism under climate extremes.     

SIGNIFICANT GROUND MOTION PARAMETERS FOR EVALUATION OF THE SEISMIC PERFORMANCE OF SLENDER MASONRY TOWERS

The evaluation of seismic risk of masonry monuments requires to study the combination of vulnerability and hazard. In the present work, the global seismic response of slender masonry towers has been studied by means of a specific 3-D fibre model. Accounting for the particular behaviour of such structures, the hazard should also be described by a suitable measure of intensity of the seismic action. A variety of different parameters relating with the ground acceleration recordings have been investigated for what regards their correlation with the damage indicators of the model. The combination of the peak ground velocity of the horizontal component and of the significant duration is an effective measure of intensity. This measure can be improved by considering the accord of the frequency content of the ground motion with the dynamical characteristics of the tower. Since in some cases the effect of the vertical component proved to be important, a further improvement can be obtained by taking into account also the vertical ground motion intensity.