Suchergebnisse

Currently, concerns are increasing that climate change may intensify natural disasters, like droughts, floods and storms which pose risks to human society, especially at the coastal urban area. This thesis studies climate change, water shortage and flood risks as well as human response measures in the highly urbanized Pearl River Delta (PRD) area in South China. Analysis on climate change in the PRD area is based on existing datasets and model projections, with an integration of literature results. Findings indicate significant climate change in both the past and future of the area, with a trend of increasing mean temperature, fluctuating precipitation, rising sea level and increasing typhoon intensity as well as the frequency of extreme weather events. In particular, the annual mean temperature in the PRD area is likely to rise by around 3℃ and precipitation to increase slightly but with greater fluctuations by 2100, while the sea level is projected to rise with an annual rate of 0.33cm to 1cm in this century. Climate change is likely to increase rainfall variability, drought intensity and duration, and damages on water-related infrastructure by extreme weather events, which all increasingly threaten the local freshwater availability. The water supply situation is becoming more complicated along with the population growth, economic development and difficulties in response/management. Hence, ensuring sufficient freshwater availability is one of the major water management challenges for all the PRD cities. Taking Hong Kong as a case study, this thesis highlights six interrelated risks within the context of climate change, namely: drought, rainstorm/flood events, sea-level rise, water pollution, social management and policy gaps. It suggests that for a sustainable future, Hong Kong needs to invest in improving water self-sufficiency, diversify water sources and conduct aggressive public awareness to increase individual adaptation to predicted climate change impacts. Flood implications of climate change trends are pronounced in most of the cities in PRD as well. The frequency and intensity of extreme weather and climate events have assumed significant change, together with continuing development in flood-prone areas, which increase both the scale and degree of urban flood risk. Further estimation was made on the flood risk in the 11 cities of PRD area from both aspects of the probability of a flood occurrence and the vulnerability of the cities. The results suggest that the exposure and sensitivity of Hong Kong, Macao, Shenzhen and Guangzhou are very high because of highly exposed populations and assets located in lowland areas. However, the potential vulnerability and risk is low due to high adaptive capacities in both hard and soft flood-control measures. A novel framework on flood responses is proposed to identify vulnerable links and response strategies in different phases of a flood event. It further suggests that the flood risks can be reduced by developing an integrated climate response strategy, releasing accurate early warning and action guidance, sharing flood related information to the public and applying the advantages of social network analysis. Further, an agent-based model is developed as an instrument to simulate the process by which individual households optimize benefits through flood response investment and damage control. The model implements a subjective response framework in which households appraise inundation scenarios according to warnings, and decide whether to invest in mitigation measures to reduce potential inundation damages. Households may have variant flood response preferences and activities but they all require investments which are consequently considered as part of the final flood losses. A case study was carried out in the Ng Tung River basin, an urbanized watershed in Northern Hong Kong. First results underline that in-time, accurate and wide-covered flood warning plays a significant role in reducing flood losses. And earlier investments in responding measures are more efficient than late activities. This dynamic agent-based modeling approach finally demonstrates its capacity to analyze the interactions between flood inundation and households responses. Overall, findings of this study help understand the level of climate change impacts and vulnerability in water domain, which are vital to gauge the cities' risks and corresponding responses and therefore inform decisions about how best to deal with emerging climate-related water risks like drought and flood. ; Es wird zunehmend befürchtet, dass der Klimawandel Naturkatastrophen (wie Dürren oder Stürme) intensivieren könnte. Dies stellt ein Risiko für menschliche Gesellschaften da, insbesondere in urbanen Küstengebieten. Die vorliegende Dissertation beschäftigt sich mit dem Zusammenhang von Klimawandel, Wasserknappheiten und Flutrisiken sowie menschlichen Reaktionen auf diese Veränderungen im stark urbanisierten Perlfluss Delta (PRD) in Südchina. Eine Analyse auf Basis des existierenden Datensatzes sowie verschiedene Modellprojektionen werden mit der Ergebnissen der ausgewerteten Literatur kombiniert, welche signifikante Klimaveränderungen für das PRD in Vergangenheit und Zukunft diagnostizieren. Der Klimawandel schreitet in dieser Region voran, was sich in höheren Durchschnittstemperaturen, Niederschlagsfluktuationen, einem Anstieg des Meeresspiegels, höherer Taifun-Intensität sowie dem gehäuften Auftreten von Extremwetterereignissen äußert. Insbesondere die Durchschnittstemperatur im PRD wird sich bis 2100 um ca. 3°C erhöhen, während die Niederschläge zwar leicht zunehmen, aber auch stärkere Schwankungen aufweisen werden. Der Meeresspiegel wird in diesem Jahrhundert laut aktueller Prognosen um 0,33 bis 1cm pro Jahr steigen. Der Klimawandel wird somit wahrscheinlich die Niederschlagsvariabilität, die Intensität und Dauer von Dürren und die Beschädigung der Wasserinfrastruktur durch Extremwetterereignisse beeinflussen. Diese Veränderungen gefährden die lokale Verfügbarkeit von Trinkwasser. Probleme bei der Bereitstellung von Wasser gehen mit Bevölkerungswachstum, ökonomischer Entwicklung und Problemen im Management bzw. bei der Problembearbeitung einher. Die Bereitstellung von Trinkwasser in ausreichenden Mengen ist daher eine der wesentlichen Herausforderungen für das Wassermanagement aller Städte im PRD. Bezogen auf den Fall Hongkong arbeitet die vorliegende Dissertation sechs miteinander verknüpften Risiken im Kontext des Klimawandel heraus: Dürren, Extremniederschläge/Überflutungen, Anstieg der Meeresspiegels, Wasserverschmutzung, soziales Management and lückenhafte politische Regulierung. Um einer nachhaltigen Zukunft entgegenzusteuern muss Hongkong in eine verbesserte Selbstversorgung mit Wasser investieren, seine Wasserquellen diversifizieren und offensive Aufklärungskampagnen durchführen, um die individuelle Anpassung an die prognostizierten Klimawandelfolgen zu erhöhen. Aktuelle klimatische Trends haben ausgeprägte Implikationen für das Flutrisiko in den meisten Städten des PRD. Die Frequenz und Intensität extremer Wetterereignisse wird sich signifikant verändern. Zusammen mit der kontinuierlichen urbanen Entwicklung in für Überflutungen anfälligen Gebieten steigt somit das Risiko für Überflutungen in städtischen Räumen. Daher wurde eine Abschätzung des Überflutungsrisikos für die 11 Städte im PRD bezüglich der Aspekte Wahrscheinlichkeit von Überflutungen und Verwundbarkeit der Städte vorgenommen. Die Ergebnisse zeigen, dass die Gefährdung (exposure) und Sensitivität zentraler Städte (Hongkong, Macao, Shenzhen und Guangzhou) auf Grund ihrer stark gefährdeten Bevölkerungen und der Konzentration von Aktiva in tiefliegenden Gebieten besonders hoch ist. Allerdings können die potenzielle Vulnerabilität und das Risiko im Falle ausgeprägter Anpassungskapazitäten (durch harte und weiche Maßnahmen der Flutkontrolle) gering sein. Ein innovativer Rahmen zur Reaktion auf Flutereignisse wird vorgeschlagen, welcher verwundbare Links und Handlungsmaßnahmen in den verschiedenen Phasen eines Flutereignisses identifiziert. Das Flutrisiko kann verhindert werden, wenn integrierte Handlungsstrategien für Klimaveränderungen entwickelt, akkurate Frühwarnungen und Handlungsanweisungen herausgegeben, überflutungsbezogene Informationen mit der Öffentlichkeit geteilt und die Vorteile der sozialen Netzwerkanalyse genutzt werden. Darüber hinaus wird ein agentenbasiertes Modell entwickelt. Dieses dient der Simulation der Prozesse, durch welche einzelne Haushalte ihre überflutungsbezogenen Handlungs- und Schadenskontrollmaßnahmen optimieren. Das Modell implementiert einen auf subjektive Reaktionen abzielenden theoretischen Rahmen, in welchem Haushalte Flutszenarien auf Grund bestehender Warnungen entwickeln und entscheiden, ob sie in Verhinderungsmaßnahmen investieren, um potenzielle Schäden durch Überflutungen zu reduzieren. Haushalte können verschiedene Präferenzen und Handlungsstrategien bezüglich Überflutungen besitzen, aber sie alle implizieren Investitionen, die daher als Teil der Verluste durch Überflutungen betrachtet werden. Eine Fallstudie wurde im Ng Tung-Becken, einem stark urbanisierten Wassereinzugsgebiet im nördlichen Hongkong, durchgeführt. Erste Ergebnisse zeigen, dass rechtzeitige, genaue und flächendeckende Flutwarnungen eine signifikante Rolle für die Reduzierungen von Verlusten durch Überflutungen spielen. Zudem sind frühzeitige Investitionen in Handlungsmaßnahmen effizienter als erst spät durchgeführte Aktivitäten. Dieser dynamische, auf einem agentenbasierten Modell beruhende Ansatz demonstriert somit seine Kapazität zur Analyse von Überflutungsrisiken und die Effekte der Handlungsmaßnahmen einzelner Haushalte. Insgesamt verbessern die Ergebnisse dieser Studie unser Verständnis von Klimawandelauswirkungen und Vulnerabilitäten im Wassersektor. Dies ist entscheidend, um das Risiko für Städte und sich daraus ergebende Handlungsmaßnahmen abschätzen, und um informierte Entscheidungen bezüglicher sich abzeichnender klimabezogener Wasserrisiken wie Dürren oder Überflutungen treffen zu können.

Free trade between the United States and Mexico is credited with having developed one of the largest bilateral trading relationships in the world. Yet Mexico-United States trade has been significant for more than a century. Our objective is to show how bilateral trade increased independently of the trade agreement that took effect in 1994, and to specify the other reasons why trade grew. We measure trade flows from the 1880s to the present and estimate a gravity model for the period 1948-2006. The gravity model shows that the fundamental characteristics of Mexico and the United States explain the volume of trade independently of the trade agreement. The trade agreement reduced uncertainty which likely had a positive effect on trade flows. Our analysis does not estimate the quantitative impact of reduced uncertainty but shows that proximity and size of the market were more significant that the trade agreement.

This open access book discusses socio-environmental interactions in the middle to late Holocene, covering specific areas along the ancient Silk Road regions. Over twenty chapters provide insight into this topic from various disciplinary angles and perspectives, ranging from archaeology, paleoclimatology, antiquity, historical geography, agriculture, carving art and literacy. The Silk Road is a modern concept for an ancient network of trade routes that for centuries facilitated and intensified processes of cultural interaction and goods exchange between West China, Central Asia, the Middle East, and the Mediterranean. Coherent patterns and synchronous events in history suggest possible links between social upheaval, resource utilization and climate or environment forces along the Silk Road and in a broader area. Post-graduates in studying will benefit from this work, as well as it will stimulate young researchers to further explore the role played by the environment in long-term socio-cultural changes.

Abstract. Private flood precautionary measures have proven to
reduce flood damage effectively. Integration of these measures into flood
response systems can improve flood risk management in high-risk areas such
as Ho Chi Minh City (HCMC). Since uptake of such measures is voluntary, it
is important to know what drives householders to implement precautionary
measures. In this study, we developed a framework representing the uptake of private precautionary measures based on protection motivation theory and
the transtheoretical model. Using empirical survey data collected from 1000
flood-prone households in HCMC, we implemented lasso and elastic-net
regression to identify the drivers of private precaution. The measures were
classified into structural measures and non-structural measures based on
whether structural changes to the building were required. The households
were classified into proactive and reactive households based on whether
their decision to reduce risk (i.e. uptake of precautionary measures) was
preceded by experiencing a flood. The data-driven model revealed that the
household's level of education, the degree of belief in the government to
implement regional flood protection measures and the degree of belief that
in case of flooding one has to deal with the consequences of flooding by
themselves positively influence the proactive uptake of non-structural
measures. Among the households that experienced flooding before implementing
the measures, the uptake was found to be driven by the severity of the
experienced damage. For the same group of households, perceiving a high
severity of future flood impacts was found to negatively influence the
uptake of structural flood precautionary measures. These results highlight
that efforts to improve the implementation of private precautionary measures
should consider the socio-economic characteristics of the members of the household, their
past flood experience and their perception of flood risk management for
communicating flood risk and incentivizing private precautionary measures.

Private flood precautionary measures have proven to reduce flood damage effectively. Integration of these measures into flood response systems can improve flood risk management in highly vulnerable areas such as Ho Chi Minh City (HCMC). Since uptake of such measures is voluntary, it is important to know what drives householders to implement precautionary measures. Protection Motivation Theory in combination with the Transtheoretical Model was applied to survey data collected from 1000 flood prone households in HCMC. Data analyses by ridge and elastic net regression revealed that, education, degree of belief that the government will implement effective flood protection measures and degree of belief that one has to deal with the consequences of flooding by themselves positively influence the proactive implementation of non-structural flood precautionary measures. Experienced increasing flood damage leads to reactive implementation of measures. But when the perceived severity of flood damage in the future was high, it discouraged implementation of structural flood precautionary measures even after experiencing a serious flood event. These important aspects should be considered when developing risk communication or incentive campaigns to promote proactive implementation of private flood precaution in HCMC.

Spanning the Yangtze River of China, the Three Gorges Dam (TGD) has received considerable concern worldwide with its potential impacts on the downstream side of the dam. This work investigated the spatio-temporal variations of suspended sediment concentration (SSC) at the downstream section of Yichang-to-Chenglingji from 2002 to 2015. A random forest model was developed to estimate SSC using MODIS ground reflectance products, and the spatio-temporal distributions of SSC were retrieved with this model to investigate the characteristics of water-silt variation. Our results revealed that, relatively, SSC before 2003 was evenly distributed in the downstream Yangtze River, while this spatial distribution pattern changed ce 2003 when the dam started storing water. Temporally, the SSC demonstrated a W-shaped curve of seasonal variation as one peak occurred in September and two troughs in March and November, and showed a significantly decreasing trend after three-stage impoundment. After official operation of the TGD in 2009, the SSC was reduced by over 40% than before 2003. Spatially, the most significant changes occurred in the upper Jingjiang section, where the SSC dropped by 45%. During all stages of impoundment, the water impoundment to 135 m in 2003 had the most significant impact on suspended sediment. The decreased SSC has led to emerging risks of bank failure, aggravated erosion of water front and aggressive down-cutting erosion along the downstream of the dam, as well as other ecological and environmental issues that require urgent attention by the government.