1,721,008 research outputs found
Drought vulnerability and risk assessments: state of the art, persistent gaps, and research agenda
No full textReducing the social, environmental, and economic impacts of droughts and identifying pathways towards drought resilient societies remains a global priority. A common understanding of the drivers of drought risk and ways in which drought impacts materialize is crucial for improved assessments and for the identification and (spatial) planning of targeted drought risk reduction and adaptation options. Over the past two decades, we have witnessed an increase in drought risk assessments across spatial and temporal scales drawing on a multitude of conceptual foundations and methodological approaches. Recognizing the diversity of approaches in science and practice as well as the associated opportunities and challenges, we present the outcomes of a systematic literature review of the state of the art of people-centered drought vulnerability and risk conceptualization and assessments, and identify persisting gaps. Our analysis shows that, of the reviewed assessments, (i) more than 60% do not explicitly specify the type of drought hazard that is addressed, (ii) 42% do not provide a clear definition of drought risk, (iii) 62% apply static, index-based approaches, (iv) 57% of the indicator-based assessments do not specify their weighting methods, (v) only 11% conduct any form of validation, (vi) only ten percent develop future scenarios of drought risk, and (vii) only about 40% of the assessments establish a direct link to drought risk reduction or adaptation strategies, i.e. consider solutions. We discuss the challenges associated with these findings for both assessment and identification of drought risk reduction measures, and identify research needs to inform future research and policy agendas in order to advance the understanding of drought risk and support pathways towards more drought resilient societies.Bundesministerium für Bildung und Forschung https://doi.org/10.13039/50110000234
Characterizing and assessing drought risks for agricultural systems : Integrating socioecological approaches at global and national levels
Full text linkDroughts are complex, multifaceted hazards that affect many regions of the world. They cascade through socioecological systems at different scales and cause severe environmental and social impacts. Agriculture bears much of the impact and, in many countries, it is the most heavily affected sector. As agricultural systems are social-ecological systems characterised by close human-environmental interaction, drought risk assessments for agricultural systems should be based on a socioecological system's perspective. Despite this, comprehensive drought risk assessments that consider the complex interaction of drought hazards, exposure, and vulnerability factors with a social-ecological approach are still the exception. Addressing this gap, this thesis presents for the first time an integrated assessment of drought risk for both irrigated and rainfed agricultural systems at the global and national scales. At the global scale, composite hazard indicators were calculated for irrigated and rainfed systems separately using different drought indices based on historical climate conditions. Exposure was analysed for irrigated and non-irrigated crops. Vulnerability was assessed through a socioecological system (SES) perspective, using socioecological susceptibility and lack of coping-capacity indicators weighed by drought experts from around the world.
The findings of the global assessment show that drought risk of rainfed and irrigated agricultural systems displays a heterogeneous pattern at the global level, with higher risk for southeastern Europe as well as northern and southern Africa (e.g., South Africa and Zimbabwe). In fact, environmental and socioeconomic factors in South Africa's and Zimbabwe's agricultural systems have been affected by drought in the past, creating cascading pressures on the nation's agro-economic and water supply systems. To understand the key drivers of drought risk and to inform proactive drought risk management, a sub-national level drought risk assessment is also presented for both countries. This assessment pioneered national-level assessments for irrigated and rainfed systems that take into account the complex interaction between different risk components, using modelling and remote sensing approaches and involving national experts in selecting vulnerability indicators and providing information on human and natural drivers.
Recognising that global drought risk assessments have been conducted to highlight the regions or countries most at risk, and that their outcomes are deemed useful to inform adaptation finance decisions, this thesis also compares the outcomes of global and regional drought risk assessments for different clusters of countries of particular relevance to international climate and disaster risk policy. The findings highlight the importance of analysing risk at multiple spatial scales to ensure no country is "left behind" in global risk and adaptation finance decisions.
Finally, the thesis discusses a systemic perspective as a way forward to assess and manage drought risks effectively. A novel drought risk framework that highlights the systemic nature of drought risks is presented. This thesis highlights the need for solutions to tackle the growing drought risks that not only consider the underlying drivers of drought risks for different sectors, systems or regions but also require an understanding of sector/system interdependencies, feedback, dynamics, compounding and concurring hazards, as well as possible tipping points and globally and/or regionally networked risks.Dürren bergen komplexe, vielschichtige Gefahren (‚hazards‘), die viele Regionen der Welt betreffen. Sie wirken sich auf verschiedenen Ebenen von sozioökologische Systemen aus und verursachen schwerwiegende ökologische und soziale Folgen. Einen Großteil dieser Folgen trägt die Landwirtschaft. Diese ist in vielen Ländern auch der am stärksten betroffene Sektor. Bei landwirtschaftlichen Systemen handelt es sich um sozial-ökologische Systeme, die durch eine enge Interaktion zwischenMensch und Umwelt gekennzeichnet sind. Daher sollten auch Dürrerisikobewertungen für landwirtschaftliche Systeme eine sozio-ökologische Systemperspektive berücksichtigen. Trotzdem sind umfassende Dürrerisikobewertungen, die die komplexen Wechselwirkungen zwischen Gefahr (‚hazards‘) , Exposition (‚exposure‘) und Vulnerabilität (‚vulnerability‘)mit einem sozial-ökologischen Ansatz berücksichtigen, immer noch die Ausnahme. Um diese Lücke zu schließen, wird in dieser Arbeit zum ersten Mal eine integrierte Bewertung des Dürrerisikos sowohl für bewässerte als auch für regengespeiste landwirtschaftliche Systeme auf globaler und nationaler Ebene vorgestellt. Auf globaler Ebene wurden zusammengesetzte Gefahrenindikatoren für bewässerte und regengespeiste Systeme getrennt berechnet, wobei verschiedene Dürreindexe auf der Grundlage historischer Klimabedingungen verwendet wurden. Die Exposition wurde für bewässerte und unbewässerte Kulturpflanzen analysiert. Die Vulnerabilität wurde aus der Perspektive des sozio-ökologischen Systems (SES) bewertet, wobei Indikatoren für sozio-ökologische Vulnerabilität und fehlende Bewältigungskapazitäten verwendet wurden, die von Dürreexperten aus aller Welt gewichtet wurden.
Die Ergebnisse der globalen Bewertung zeigen, dass das Dürrerisiko von regengespeisten und bewässerten landwirtschaftlichen Systemen auf globaler Ebene ein heterogenes Muster aufweist, mit einem höheren Risiko für Südosteuropa sowie für das nördliche und südliche Afrika (z. B. Südafrika und Simbabwe). In der Tat waren die Umwelt- und sozioökonomischen Faktoren in den landwirtschaftlichen Systemen Südafrikas und Simbabwes in der Vergangenheit von Dürre betroffen, was zu einer kaskadierendenBelastung der agrarökonomischen und wasserwirtschaftlichen Systeme der Länder führte. Um die wichtigsten Faktoren für das Dürrerisiko zu verstehen und Informationen für ein proaktives Dürrerisikomanagement zu erhalten, wird für Südafrika und Simbabwe auch eine Bewertung des Dürrerisikos auf subnationaler Ebene vorgelegt. Mit dieser Bewertung wurde auf nationaler Ebene für bewässerte und regengespeiste Systeme Pionierarbeit geleistet, denn sie berücksichtigt die komplexen Wechselwirkungen zwischen verschiedenen Risikokomponenten, nutzt Modellierungs- und Fernerkundungsansätze und bezieht nationale Experten in die Auswahl von Vulnerabiliätsindikatoren und die Bereitstellung von Informationen über menschliche und natürliche Faktoren mit ein.
In Anerkennung der Tatsache, dass globale Dürrerisikobewertungen durchgeführt wurden, um die am stärksten gefährdeten Regionen oder Länder hervorzuheben, und deren Ergebnisse als nützlich erachtet werden, um Entscheidungen zur Anpassungsfinanzierung zu treffen, werden in dieser Arbeit auch die Ergebnisse globaler und regionaler Dürrerisikobewertungen für verschiedene Ländergruppen verglichen, die für die internationale Klima- und Katastrophenrisikopolitik von besonderer Bedeutung sind. Die Ergebnisse verdeutlichen, wie wichtig es ist, das Risiko auf mehreren räumlichen Ebenen zu analysieren, um sicherzustellen, dass kein Land bei globalen Risiko- und Anpassungsfinanzierungsentscheidungen "zurückgelassen" wird.
Abschließend wird in dieser Arbeit eine systemische Perspektive erörtert, die eine wirksame Bewertung und Bewältigung von Dürrerisiken ermöglichen soll. Es wird ein neues Rahmenwerk für Dürrerisiken vorgestellt, der den systemischen Charakter von Dürrerisiken hervorhebt. Diese These unterstreicht die Notwendigkeit von Lösungen zur Bewältigung der zunehmenden Dürrerisiken, die nicht nur die zugrunde liegenden Faktoren für Dürrerisiken in verschiedenen Sektoren, Systemen oder Regionen berücksichtigen, sondern auch ein Verständnis der gegenseitigen Abhängigkeiten von Sektoren/Systemen, Rückkopplungen, Dynamiken, sich verstärkenden und konkurrierenden Gefahren sowie möglicher Kipppunkte und global und/oder regional vernetzten Risiken erfordern
Sediment-associated cues for larval settlement of Polydora cornuta and Streblospio benedicti (Polychaeta, Spionidae)
Full text linkPatchy distribution of infaunal polychaetes may result from active site selection of larvae guided by sediment associated bacterial cues. This hypothesis was tested in still water laboratory settlement assays with and without choice option for larvae of two spionid polychaetes with indirect development: Polydora cornuta and Streblospio benedicti. Larvae were able to accept or reject attractive and unattractive sediment qualities in the assays in a species specific manner. Two out of 15 tested bacterial isolates significantly triggered settlement of P. cornuta and S. benedicti larvae in a cell density dependent manner. The heat labile sediment associated settlement cue was at least partially of bacterial origin but not related to a unique bacterial genus. Furthermore, the settlement of P. cornuta was influenced by gregarious behavior and the signal was mainly harboured in sediments formerly inhabited by conspecific adults
Assessment of land/catchment use and degradation
No full textAgricultural conversion of land and rapid urbanization are the primary drivers of land cover and land use change (LCLUC) globally, resulting in massive deforestation, drainage of wetlands, effects on the water cycle, alteration of sediment budgets, and acceleration of land degradation and desertification. This has taken place across various spatial and temporal scales. This chapter provides an overview of hydrological impact of land use change at these multiple scales. It also reviews the state of the art in analyzing LCLUC impacts on water quality outcomes and showcases where different techniques have been used to reveal the relationship between the two. Finally, the chapter addresses the impacts LCLUC generated within entire basins can have on delta landscapes, which constitute very dynamic and fragile environments with typically high economic activities and population densities
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Editorial: Knowledge gaps from the IPCC special report on the ocean and cryosphere in a changing climate and recent advances (volumes I and II)
Full text linkThis is the final version. Available from Frontiers Media via the DOI in this record. Natural Environment Research CouncilSwiss Agency for Development and CooperationSwiss Agency for Development and CooperationSwiss Academy of Science
What Mekong Delta Communities Can Teach Us About Access to Safe Water
No full textNo abstract available
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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