Clustering of seasonal events: A simulation study using circular methods

ABSTRACT

In a changing climate, changes in timing of seasonal events such as floods and flowering should be assessed using circular methods. Six different methods for clustering on a circle and one linear method are compared across different locations, spreads, and sample sizes. Best results are obtained when clusters are well separated and the number of observations in each cluster is approximately equal. Simulations of flood-like distributions are used to assess and explore clustering methods. Generally, k-means provides results that are close to the expected results, some other methods perform well under specific conditions, but no single method is exemplary.     

A Review of Risk Perceptions and Other Factors that Influence Flood Mitigation Behavior

In flood risk management, a shift can be observed toward more integrated approaches that increasingly address the role of private households in implementing flood damage mitigation measures. This has resulted in a growing number of studies into the supposed positive relationship between individual flood risk perceptions and mitigation behavior. Our literature review shows, however, that, actually, this relationship is hardly observed in empirical studies. Two arguments are provided as an explanation. First, on the basis of protection motivation theory, a theoretical framework is discussed suggesting that individuals’ high‐risk perceptions need to be accompanied by coping appraisal to result in a protective response. Second, it is pointed out that possible feedback from already‐adopted mitigation measures on risk perceptions has hardly been considered by current studies. In addition, we also provide a review of factors that drive precautionary behavior other than risk perceptions. It is found that factors such as coping appraisal are consistently related to mitigation behavior. We conclude, therefore, that the current focus on risk perceptions as a means to explain and promote private flood mitigation behavior is not supported on either theoretical or empirical grounds.     

Households' Perceived Personal Risk and Responses in a Multihazard Environment

This study proposed and tested a multistage model of household response to three hazards—flood, hurricane, and toxic chemical release—in Harris County Texas. The model, which extends Lindell and Perry's (1992, 2004) Protective Action Decision Model, proposed a basic causal chain from hazard proximity through hazard experience and perceived personal risk to expectations of continued residence in the home and adoption of household hazard adjustments. Data from 321 households generally supported the model, but the mediating effects of hazard experience and perceived personal risk were partial rather than complete. In addition, the data suggested that four demographic variables—gender, age, income, and ethnicity—affect the basic causal chain at different points.     

东汉水灾及其救助措施

东汉水灾发生次数多,灾区面积大,灾情严重。在大灾面前,人们奋起抗争,采取了形式多样的救灾措施,效果显著。但救灾过程中也有不和谐因素存在,当为后世之鉴。     

苗族创世神话：洪水故事与兄妹结婚

洪水故事与兄妹结婚,是苗族人民流行最广最古老最庄严的民族民间故事。据专家考证,中国史籍记载之伏羲与女娲,源于苗族的洪水故事与兄妹结婚。本文运用民族人类学的田野材料和历史学的文献材料,综合考察苗族这一古老的经典神话传说。彰显苗族悠久的历史与文化。     

Structured Coupling of Probability Loss Distributions: Assessing Joint Flood Risk in Multiple River Basins

Losses due to natural hazard events can be extraordinarily high and difficult to cope with. Therefore, there is considerable interest to estimate the potential impact of current and future extreme events at all scales in as much detail as possible. As hazards typically spread over wider areas, risk assessment must take into account interrelations between regions. Neglecting such interdependencies can lead to a severe underestimation of potential losses, especially for extreme events. This underestimation of extreme risk can lead to the failure of riskmanagement strategies when they are most needed, namely, in times of unprecedented events. In this article, we suggest a methodology to incorporate such interdependencies in risk via the use of copulas. We demonstrate that by coupling losses, dependencies can be incorporated in risk analysis, avoiding the underestimation of risk. Based on maximum discharge data of river basins and stream networks, we present and discuss different ways to couple loss distributions of basins while explicitly incorporating tail dependencies. We distinguish between coupling methods that require river structure data for the analysis and those that do not. For the later approach we propose a minimax algorithm to choose coupled basin pairs so that the underestimation of risk is avoided and the use of river structure data is not needed. The proposed methodology is especially useful for large‐scale analysis and we motivate and apply our method using the case of Romania. The approach can be easily extended to other countries and natural hazards.     

Stakeholder Views on Flood Risk Management in Hungary''s Upper Tisza Basin

With escalating costs of flood mitigation and relief, a challenge for the Hungarian government is to develop a flood mitigation and insurance/relief system that is viewed as efficient and fair by the many stakeholders involved. To aid policymakers in this task, this article reports on a recent study to elicit stakeholder views on flood risk management in the Upper Tisza Basin, including views on appropriate means of reducing losses and for transferring the residual losses from the direct victims to taxpayers or an insurance pool. This study is part of a project to develop an integrated approach to flood risk management coordinated by the International Institute of Applied Systems Analysis (IIASA) in collaboration with Swedish and Hungarian researchers. The discussion begins by describing the background of flood risk management problems in the Upper Tisza Basin. The results of interviews carried out with selected key stakeholders and the results of a public survey eliciting views on flood risk management are reported. The final section draws conclusions on incorporating stakeholder views into a flood risk management model, which will be used to illustrate policy paths at an upcoming stakeholder workshop. The conclusions are also of direct interest to Hungarian policymakers.     

论魏晋南北朝时期的水灾与救助

魏晋南北朝时期是我国历史上的水灾多发期。水灾主要集中在5、6、7、8月和长江、黄河流域。水灾的频繁发生,给社会经济和广大人民的生命财产带来了巨大损失。各封建王朝的统治者对救灾工作高度重视,及时采取实物救助、调粟赈民、减免租调、借贷及兴修水利等一系救助措施,对于减轻灾害,维护社会稳定,保障民生及促进社会经济的恢复与发展起到了一定的积极作用。     

The Right to Aid: Perceptions and Practices of Justice in a Flood-Hazard Context in Jakarta,Indonesia

Regular floods impact negatively on the health and wellbeing of slum dwellers in Jakarta and it is understandable that the victims seek access to justice. Fieldwork in one of Jakarta's most flood-prone neighbourhoods, Bantaran Kali, reveals that riverbank settlers there access what they perceive to be justice by engaging in a number of different social networks that are neither formal nor informal—they feature in between civil society and the state. In this article I explore the network ties that are used by individual slum dwellers to access justice. I will show that in the context of extreme flood risk and related uncertainty, this form of social capital makes a significant difference to the community and to households, and with respect to individuals' resilience. By exploring this particular avenue of access to justice, I show that a sense of justice is achieved not through the formal agencies of government but by means of social networks in a space that fits uneasily in the dichotomy of state and non-state.