Extreme Natural Events Research Articles

Effects of extreme natural events on the provision of ecosystem services in a mountain environment: The importance of trail design in delivering system resilience and ecosystem service co-benefits

A continued supply of ecosystem services (ES) from a system depends on the resilience of that system to withstand shocks and perturbations. In many parts of the world, climate change is leading to an increased frequency of extreme weather events, potentially influencing ES provision. Our study of the effects of an intense rainfall event in Gorce National Park, Poland, shows: (1) the intense rainfall event impacted heavily on the supply of ES by limiting potential recreation opportunities and reducing erosion prevention; (2) these negative impacts were not only restricted to the period of the extreme event but persisted for up to several years, depending on the pre-event trail conditions and post-event management activities; (3) to restore the pre-event supply of ES, economic investments were required in the form of active repairs to trails, which, in Gorce National Park, were an order of magnitude higher than the costs of normal trail maintenance; and (4) when recreational trails were left to natural restoration, loss of biodiversity was observed, and recovery rates of ES (recreation opportunities and soil erosion prevention) were reduced in comparison to their pre-event state. We conclude that proper trail design and construction provides a good solution to avoid some of the negative impacts of extreme events on recreation, as well as offering co-benefits in terms of protecting biodiversity and enhancing the supply of regulating services such as erosion prevention.

Drinking water vulnerability in rural coastal areas of Bangladesh during and after natural extreme events

The collapse of drinking water management systems is one of the most serious consequences of natural disasters. This article aims to analyze the vulnerability of drinking water management during and after a natural disaster in the rural and coastal areas of Bangladesh. We have considered the extreme event of cyclone ‘Aila’, which devastated the coastal district of Satkhira in 2009. In the study area, the collection of drinking water in normal situations is difficult mainly because of the spatially varied availability of drinking water sources (tube wells, ponds and rainwater harvesting units). In addition, the decreasing trend in pre-monsoon rainfall intensity as well as the increased salinity play a significant role in this regard. Due to the destruction of the coastal embankment during cyclone ‘Aila’, saltwater intruded into the locality and heavily damaged the drinking water sources. To analyze the associated vulnerability factors in the drinking water sector, we conducted a household-based structured questionnaire survey in three ‘mouza’ (revenue collection unit) of the Satkhira district. Using principal component analysis, we have identified six factors influencing drinking water vulnerability. The factors are related to warning dissemination, damage to water sources, damage to household’s water reserves, collection time, family composition, and frequency of water collection. We have used the factors to prepare an index for the comparative analysis of vulnerability among the three ‘mouza’. Considering the vulnerability issues, the article concludes by presenting the scope for a robust drinking water management plan for the coastal areas of Bangladesh.

Drivers and consequences of land use patterns in a developing country rural community

Deforestation has caused degradation of ecosystem services around the world, undermining soil stability, biodiversity, protection from natural extreme events, and long-term food security. The purpose of this study is to examine closely the interrelationships of these factors in a coastal area on the diversity-rich island of Mindoro, the Philippines, where poverty is both a driver and a result of complex ecological problems. Soil and vegetation assessments of sites with differing land use intensities were compared, and narrative interviews were conducted to augment the overview derived from the quantitative analyses. Forested and agricultural slopes have a history of exploitation by the indigenous minority and show distinct signs of erosion. Species diversity on intensely cultivated, degraded and Imperata cylindrica-dominated slash-and-burn fallow sites is low. Secondary forests with shallow soils are able to recover when left untouched for several years. Floodplain soils are productive and farmed extensively with rice and coconut by the growing Tagalog majority. Population pressure and a gradient of political and economic power between the dominant Tagalog and the indigenous (Mangyans) hinder efforts at poverty alleviation. The resulting economic needs drive illegal logging and intensification of agriculture which, if continued, will lead to further decline of forest and soil resources, endangering livelihood and biodiversity.

Speeding up the clock in remote sensing: identifying the ‘black spots’ in exposure dynamics by capitalizing on the full spectrum of joint high spatial and temporal resolution

Increasing human and monetary losses resulting from extreme natural events over the past decades have been documented in corresponding disaster data compilations such as the open-access EM-DAT, SHELDUS, and DesInventar or the private domain NatCatSERVICE (Munich Re) and Sigma (Swiss Re) databases. One of the most imminent questions in disaster risk research is therefore to identify the main root causes of those increasing impacts as a first step toward being able to address those aspects in mitigation planning. Statistical evidence about increase in frequency and intensity of hazardous extreme events depends on the quality and quantity of data available for probabilistic trend evaluation, and varies across regions and in particular for different types of events. The question is now what can remote sensing contribute to mapping exposure and more specifically elements at risk and their relevant characteristics that are needed for estimating potential losses and to initiate adequate mitigation strategies? It is clear that in a ‘static’ data environment characterized by temporal snapshots at regular intervals (i.e., as opposed to temporally continuous acquisition), as it has been common in high spatial resolution remote sensing, physical objects and structures can be well detected and characterized. Analyzing functional parameters or even relationships requires linking ancillary data to the remote sensing-based physical base Information. This article, however, focuses foremost on recent developments regarding remote sensing as a sole data source and just briefly concludes with a short outlook on associated integrative multisource data analysis.

Analyzing streamflow extremes in the upper Ürümqi River with the generalized Pareto distribution

The generalized Pareto distribution (GPD), as one of the most important distributions in statistical theory of extreme value, is often used to explain the probability of extreme events in nature, through setting up a model with the observation points exceeding the threshold. This paper uses GPD model to fit the distributions of the relatively large and small monthly average discharge of Urumqi River in Northwest China and gives the detailed steps of this method. Firstly, the Mean Excess, shape parameter and modified scale parameter plots are applied to determine the thresholds; then the parameters of GPD are estimated by the maximum likelihood method; next the models are diagnosed by the probability and quantile plots; finally the return levels and the corresponding 95 % confidence intervals of the discharge are calculated by the maximum likelihood and profile likelihood methods, respectively. The results show that the return levels of the maximum monthly average discharge with the return periods 10, 25, 50 and 100 years are 35.4, 39.9, 43.2 and 46.3 m3 s−1, respectively, and the return levels of the minimum monthly average discharge with the return periods 10, 25, 50 and 100 years are 0.60, 0.43, 0.30 and 0.18 m3 s−1, respectively. Some comparisons are also made between the generalized extreme value (GEV) and GPD models. The results of these two models are close to each other while the GPD model should be more reliable because it can make use of more information than the GEV model. This paper proposes a complete framework for modeling hydrological data by GPD model.

The impact of extreme weather conditions on long distance travel behaviour

This paper examines traveller attitudes and responses towards disruption from weather and natural events. An internet-based travel behaviour survey was conducted with more than 2000 respondents in London and Glasgow. Of these respondents, 740 reported information on over 1000 long distance trips affected by extreme weather and natural events over the previous three years. Results show respondents are generally cautious towards travelling during extreme weather events. For a slight majority in the case of air and public transport, and a greater one in the case of car, travellers did not considerably alter their travel plan following the disruption. This was explained not only by less disruptive weather conditions (with heavy snow and volcanic ash being the most disruptive) and impact, but also by the relative importance of their trips. Differences between transport modes were not substantial. Business trips sometimes appeared to give travellers more flexibility, some other times not. Origin and destination did have an impact on reaction, as well as the presence of children whilst travelling. Mixed results were obtained about socio-economic and attitudinal variables. Age in particular did not appear to have a significant effect. Whilst most respondents did acknowledge no external influence in their decision, results showed an important contribution of transport organisation staff, as well as home and mobile internet technology. A limited but still considerable number of respondents indicated their closest friends/relatives as the main influence of their decisions. The results will help planners deploy strategies to mitigate the negative effects of weather related disruptions.

Design and development of innovative passive valves for Nuclear Power Plant applications

The recent Fukushima accident has resulted in an increased need for passive safety systems in upcoming advanced reactors. In order to enhance the global contribution and acceptability of nuclear energy, proven evidence is required to show that it is not only green but also safe, in case of extreme natural events. To achieve and establish this fact, we need to design, demonstrate and incorporate reliable ‘passive safety systems’ in our advanced reactor designs.In Nuclear Power Plants (NPPs), the use of passive safety systems such as accumulators, condensing and evaporative heat exchangers and gravity driven cooling systems provide enhanced safety and reliability. In addition, they eliminate the huge costs associated with the installation, maintenance and operation of active safety systems that require multiple pumps with independent and redundant electric power supplies. As a result, passive safety systems are preferred for numerous advanced reactor concepts. In current NPPs, passive safety systems which are not participating in day to day operation, are kept isolated, and require a signal and external energy source to open the valve. It is proposed to replace these valves by passive components and devices such as self-acting valves, rupture disks, etc.Some of these innovative passive valves, which do not require external power, have been recently designed, developed and tested at rated conditions. These valves are proposed to be used for various passive safety systems of an upcoming Nuclear Power Plant being designed by India. For example, the Hot Shutdown Passive Valves (HSPV), developed for the decay heat removal system keep the main heat transport system under hot conditions by passively sensing and controlling the system pressure. Another crucial and important valve which has been successfully developed is the Poison Injection Passive Valve (PIPV) for the Passive Poison Injection System. It not only provides higher reliability, but also ensures safe shutdown of the reactor in case of insider threats or malevolent acts in disabling active shutdown system of the reactor.Recently, an innovative valve called the Accumulator Isolation Passive Valve (AIPV) has been developed for the Emergency Core Cooling System (ECCS), which is engineered to mitigate the consequences of Loss of Coolant Accident (LOCA). During normal operation of the reactor, the pressurized accumulators (55bar) are kept isolated from the reactor core (70bar) by means of AIPVs. In case of a LOCA, these passive valves open when the main heat transport system pressure falls to a desired value. For prolonged cooling of the core, these passive valves regulate the discharge in a desired manner. These are non-standard, high pressure and high temperature valves, which are unavailable commercially and hence have to be indigenously designed and developed.This paper primarily deals with the design, development and testing of Accumulator Isolation Passive Valves (AIPV) proposed to be used in the ECCS. A 25NB size AIPV has been designed and successfully tested at Integral Test Loop (ITL) under simulated reactor conditions. It is a self-acting, ANSI 600 rating valve, which requires no external energy (i.e., neither air nor electrical power). It not only provides passive isolation but also passively controls high pressure liquid discharge through it. The design concept of the valve, functional performance, in situ valve testing methodology and the test results at simulated conditions are discussed.

An overarching risk assessment process to evaluate the risks associated with infrastructure networks due to natural hazards

In Europe, extreme natural hazard events are not frequent but due to the complex interdependency of the infrastructure systems these events can have a devastating impact in any part of Europe. Protection against the impacts of natural hazards must be guaranteed for people to work and live in a secure and resilient environment. People who manage infrastructure have to handle these risks. The proposed overarching risk assessment process is constructed in a way so that computational support can be constructed in modules. Therefore, each module interacts with other modules by receiving and delivering information. The content of the modules depends on the established context of the risk assessment process. The use of the overarching risk assessment process is demonstrated by using it to evaluate infrastructure related risk due to natural hazards for an example region in Switzerland.

A Multi-Method Approach to Develop Extreme Storm Surge Events to Strengthen the Resilience of Highly Vulnerable Coastal Areas

The North Sea coast is seriously threatened by storm surges. Climate change and its consequences, such as rising sea level, will have a serious impact on the safety of people and economic assets in coastal areas. The uncertainties resulting from these consequences necessitate new concepts for coastal protection, together with new extreme storm surge scenarios under current and future climate conditions. Extensive knowledge about extreme storm surge events is essential to strengthen the resilience of highly vulnerable coastal areas. Based on the knowledge about extreme events safety standards for coastal regions could be newly defined, improved or re-defined. This helps to strengthen the resilience by taking into account the natural extreme events as well as the costs for measures of coastal defense. This paper focuses on the results of subproject la of the XtremRisK project with the aim to determine the relevant extreme events under today's conditions. Within the process in the XtremRisK project, these events were taken as a basis to assess extreme events under conditions reflecting the climate change scenarios. Within the scope of this project, methodical alternatives for the calculation of extreme events were evaluated. It turns out that empirical and numerical, as well as statistical approaches have different strengths as each possesses various restraints. In order to utilize the advantages and minimize the limitations, a multi-method approach was developed in which existing methods were exercised and brought together. The multi-method approach facilitates consideration of all storm surge components at their maximum value. Based on validation of the meteorology and consideration of the hydrodynamics, nonlinear effects between the storm surge components can be included. Examination of the storm surge curve is a special characteristic of the approach that enables consideration of the whole storm surge run. The basic concept was to regard results as ascertained only if they were proven by multiple currently valid methods. The extreme storm surges calculated in this way are statistically classified by subproject lb [see Wahl et al., 2015 in this journal] and used within the analysis of the failure mechanism of the existing flood defence structures by subproject 2 [see Naulin et al., 2015 in this journal].

Extreme probing of particle motions in turbulence

AbstractExtreme behaviour of fluid and material motions needs to be understood for engineering processes and the behaviour of clouds or plumes of pollution. Applications in the natural environment require scaling of turbulence behaviour and models beyond current computational or laboratory understanding. New computational studies of Biferale et al. (J. Fluid Mech., 2014, vol. 757, pp. 550–572) are probing new regimes of scaling of extreme random events in nature produced by turbulent fluctuations trending towards applications in environmental prediction.

Linking disaster resilience and urban sustainability: a glocal approach for future cities.

Resilience and sustainability will be two primary objectives of future cities. The violent consequences of extreme natural events and the environmental, social and economic burden of contemporary cities make the concepts of resilience and sustainability extremely relevant. In this paper we analyse the various definitions of resilience and sustainability applied to urban systems and propose a synthesis, based on similarities between the two concepts. According to the proposed approach, catastrophic events and the subsequent transformations occurring in urban systems represent a moment in the city life cycle to be seen in terms of the complex sustainability framework. Hence, resilience is seen as a requirement for urban system sustainability. In addition, resilience should be evaluated not only for single cities, with their physical and social systems, but also on a global scale, taking into account the complex and dynamic relationships connecting contemporary cities.

Development, global change and traditional food security in Pacific Island countries

While islands have been identified in numerous discourses as being highly vulnerable, food security was a cornerstone of many traditional Pacific Island societies from inland and coastal communities in large islands with considerable natural assets to those that occupied extremely small, low-lying atolls with little or no soil and limited water resources. This was sustained through agro-ecological biodiversity, the production of surpluses which enabled food preservation and storage to be practiced and underpinned networks of exchange and mutual support that were particularly important during times of hardship such as disruptive extreme natural events, the use of resilient crops and using ‘famine’ foods. Colonisation, the introduction of new religions, the spread of capitalism, most recently in the context of globalisation, has seen many of these practices decline (some have disappeared altogether) as crop diversity has been reduced (making way for export products such as copra), food storage and preservation are now rarely practised, resilient crops have been replaced, famine foods have lost their importance in the face of disaster relief, and many traditional networks have declined. Food imports have become critical, not only in the growing urban areas, but also in rural communities. The paper concludes by addressing key challenges facing Pacific Island countries in order to revitalise those traditional elements of food security in ways that are likely to find acceptance in contemporary society and enable them to adapt to the effects of climate change.

Mapping Natural Hazard Impacts on Road Infrastructure—The Extreme Precipitation in Baden-Württemberg, Germany, June 2013

Infrastructures in Europe have been affected by impacts of extreme natural events with increasing frequency over the past decades. One of the most recent examples is the flooding that affected parts of Germany in June 2013. Global warming is expected to change patterns of climate-related extreme events affecting infrastructure. This article presents an explanatory approach. Based on an observational design, causal connections between the occurrence and patterns of extreme events and related road infrastructure impacts are analyzed. The hazard mapping case study in the state of Baden-Wurttemberg combines traffic information and data on the June 2013 extreme precipitation in Germany. It examines the precipitation occurrence and road infrastructure impact characteristics in Baden-Wurttemberg and identifies spatiotemporal hazard patterns. The article suggests further research needs and fields of application for risk mapping in climate change adaptation research in Germany.

Predominant bacterial and fungal assemblages in agricultural soils during a record drought/heat wave and linkages to enzyme activities of biogeochemical cycling

Identification of microbial assemblages predominant under natural extreme climatic events will aid in our understanding of the resilience and resistance of microbial communities to climate change. From November 2010 to August 2011, the Southern High Plains (SHP) of Texas, USA, received only 39.6mm of precipitation (vs. the historical average of 373mm) and experienced the three hottest months (June–August 2011) since record keeping began in 1911. The objective of this study was to characterize soil bacterial (16 S rRNA gene) and fungal (internal transcribed spacer 1–4, ITS1-ITS4) species distribution and diversity via pyrosequencing during the peak of the drought/heat wave in July 2011 and when the Drought Index and temperatures were lower in March 2012. Samples were collected from two different soil types (loam and sandy loam) under two different dryland cropping histories (monoculture vs. rotation). Fungal Diversity Indexes were significantly higher after the drought/heat wave while Bacterial Indexes were similar. Bacterial phyla distribution in July 2011 was characterized by lower relative abundance of Acidobacteriaand Verrucomicrobia, and greater relative abundance of Proteobacteria, Chloroflexi, Actinobacteria and Nitrospirae than March 2012 samples. Further grouping of pyrosequencing data revealed approximately equal relative proportions of Gram positive (G+) and Gram negative (G−) bacteria in July 2011, while G− bacteria predominated in March 2012. Fungal class Dothideomycetes was approximately two times greater in July 2011 than in March 2012, while the class Sordariomycetes and a group of unidentified OTUs from Ascomycota increased from July 2011 to March 2012. Microbial community composition was less influenced by management history than by the difference in climatic conditions between the sampling times. Correspondence analysis identified assemblages of fungal and bacterial taxa associated with greater enzyme activities (EAs) of C, N, or P cycling found during the drought/heat wave. Microbial assemblages associated with arylsulfatase activity (key to S cycling), which increased after the drought/heat wave, were identified (Streptomyces parvisporogenes, Terrimonas ferruginea and Syntrophobacter sp.) regardless of the soil and management history. The distinct microbial composition found in July 2011 may represent assemblages essential to maintaining ecosystem function during extreme drought and intense heat waves in semiarid agroecosystems.

Linking Coastal Disasters and Migration: A Case Study of Kutubdia Island, Bangladesh

On 4 August 2012, the southeastern part of Kutubdia Island, Bangladesh, experienced coastal erosion and flooding associated with tidal waves, storms, and continuous heavy rainfall for two days. This provided a unique opportunity to study the relationship between rapid-onset disasters and migration decisions of individual households perpetually living under environmental risk. Using Kutubdia Island as a case study, this article examines the migration decisions of respondents in the immediate aftermath of two extreme natural events. Relevant data were primarily collected from a questionnaire survey conducted nearly two months after the occurrence of the event. The study's findings support the view that both environmental and nonenvironmental factors lead to migration. The article outlines several areas for further research on the links between migration and environmental stress.

Model of Assessing the Impact of Rare Events in Aviation Security Investments Projects

The problem of optimal dynamic allocation of resources in security should be built in such a manner to include the impact assessment of rare events, such as natural or asymmetric extreme events. This paper presents a model for the analysis of investment situations that involves real options with multiple sources of jump risk and identification of management solutions that increase the value of the investment opportunity using Wiener processes and Poisson distribution. The results are solutions for improved decision-making in aviation systems.

A two-step framework for over-threshold modelling of environmental extremes

Abstract. The evaluation of the probability of occurrence of extreme natural events is important for the protection of urban areas, industrial facilities and others. Traditionally, the extreme value theory (EVT) offers a valid theoretical framework on this topic. In an over-threshold modelling (OTM) approach, Pickands' theorem, (Pickands, 1975) states that, for a sample composed by independent and identically distributed (i.i.d.) values, the distribution of the data exceeding a given threshold converges through a generalized Pareto distribution (GPD). Following this theoretical result, the analysis of realizations of environmental variables exceeding a threshold spread widely in the literature. However, applying this theorem to an auto-correlated time series logically involves two successive and complementary steps: the first one is required to build a sample of i.i.d. values from the available information, as required by the EVT; the second to set the threshold for the optimal convergence toward the GPD. In the past, the same threshold was often employed both for sampling observations and for meeting the hypothesis of extreme value convergence. This confusion can lead to an erroneous understanding of methodologies and tools available in the literature. This paper aims at clarifying the conceptual framework involved in threshold selection, reviewing the available methods for the application of both steps and illustrating it with a double threshold approach.

Percepção das Populações Costeiras sobre os Efeitos dos Eventos Adversos no Extremo Sul de Santa Catarina − Brasil

This study addresses the extreme natural events occurring on the coast of Santa Catarina. These events affect rural and urban areas therefore the purpose of...

Special Section on Performance of Bridges under Critical Natural Hazards

In recent years, extreme monsoon events and devastating earthquakes have caused serious damage to infrastructure, including bridges. Failures of bridges not only result in threats to vehicles and people traveling on them at the time of the failure but also interrupt emergency evacuation and rescue traffic, increasing the severity of the disaster and adding to casualties and economic loss. Often, awareness of the need for design or retrofit code revisions is raised immediately following extreme hazard events. Bridges that fail during extreme natural hazards usually have complicated failure causes, including environmental system collapses and massive structural malfunctions. Forensic investigations and performance analyses for bridges suffering such natural hazard events can be more challenging than those for bridges that fail in general service condition. General investigation guidelines or specific observational methods for such forensic investigations are not an easy task. Thus, actual performance of bridges under critical natural hazards is of great interest to practicing engineers and researchers. This special section of the Journal of Performance ofConstructed Facilities (JPCF) was proposed in an effort to introduce the current state-of-the-art for forensic investigations of bridge failures in recent extreme natural hazard events and to provide insights of performance analysis for the behavior of bridges under such extreme natural hazards. Fortunately, we were able to invite professional experts who had personally been involved in forensic investigation, failure analysis, and performancemonitoring during recent extreme natural hazards including the 2011 Turkey Van Earthquake, the 2010–2011 New Zealand Christchurch Earthquakes, the 2011 Japan Tohoku Earthquake, the 2005 Hurricane Katrina in the United States, and the 2009 Typhoon Morakot that overran Taiwan. Case histories and performance data presented in these invited papers are invaluable to practicing engineers and researchers. This special section includes case histories of bridge performance involving more than 20 bridges suffering from a variety of natural hazards such as strong ground motions, soil liquefaction, tsunami, storm surge, extreme winds, scour, and debris impact. Whether the bridge was damaged, failed, or luckily survived, such performance information and analysis results are instrumental to bridge design and retrofit against critical natural hazards, including great earthquakes and massive storms. Results of the forensic investigations and analyses have deterministic influences on upgrading guidelines of risk assessment, hazard mitigation, structural design, and retrofit. Invited papers within this special section are generally divided into two major categories: bridge performance under seismic hazards and under storm hazards. The reported seismic hazards include strong ground motion in a recent Turkish earthquake and the Japan Tohoku Earthquake that caused severe damage to both highway and railroad bridges. These bridges were in locations that had undergone in-depth evaluations and design code revolutions in recent years. Very rare, yet devastating, failures caused by the tsunami accompanying the 2011 Japan Tohoku Earthquake are instructive not only to bridge engineers, but also to the general public. Studying these failures leads to a better understanding of the power of Mother Nature. A research team from the University of Canterbury at Christchurch, New Zealand, introduces valuable performance data from bridges suffering from soil liquefaction and describes useful investigation practices. Such soil liquefaction causing bridge damage was broadly observed in previous large earthquakes, yet less detailed forensic investigation works were previously reported. Both the 2005 Hurricane Katrina and the 2009 TyphoonMorakot are recognized as critical storm events. Both resulted in substantial damage to bridges and a large number of bridge failures. Invited papers contributed by the Bridge Technology Office of the U.S. Federal Highway Administration (FHWA) and by Taiwanese research groups provide valuable forensic investigation and failure analysis techniques. Study efforts described in these papers are applicable internationally including advanced field investigation technologies and innovative Fig. 1. Wei F. Lee, Ph.D., A.M.ASCE, Guest Editor

Status of Coastal Plantation in Chittagong Coastal Forest Division

The study was conducted to highlight the status and beneficial role of coastal plantation in Chittagong Coastal Forest Division. Mangrove, non-mangrove and strip plantation were raised in 70 beats under12 ranges in the Division. Among all the Ranges, mangroves were dominant and cover an area of 46367.94 ha plantations. Coastal plantations damages during natural calamities but mostly damages by manmade activities which makes coastal areas more vulnerable to natural disasters. Mangroves and coastal forests play an important role to reduce the damages and protect human lives by acting as protective shield during extreme natural events. Coastal plantation provides benefits in terms of disaster mitigation, protection of lives and resources, living standard and resource development and preservation of environment.