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Die Arbeit gibt einen Einblick in die Verständigungspraxen bei Stadtführungen mit (ehemaligen) Obdachlosen, die in ihrem Selbstverständnis auf die Herstellung von Verständnis, Toleranz und Anerkennung für von Obdachlosigkeit betroffene Personen zielen. Zunächst wird in den Diskurs des Slumtourismus eingeführt und, angesichts der Vielfalt der damit verbundenen Erscheinungsformen, Slumming als organisierte Begegnung mit sozialer Ungleichheit definiert. Die zentralen Diskurslinien und die darin eingewobenen moralischen Positionen werden nachvollzogen und im Rahmen der eigenommenen wissenssoziologischen Perspektive als Ausdruck einer per se polykontexturalen Praxis re-interpretiert. Slumming erscheint dann als eine organisierte Begegnung von Lebensformen, die sich in einer Weise fremd sind, als dass ein unmittelbares Verstehen unwahrscheinlich erscheint und genau aus diesem Grund auf der Basis von gängigen Interpretationen des Common Sense ausgehandelt werden muss. Vor diesem Hintergrund untersucht die vorliegende Arbeit, wie sich Teilnehmer und Stadtführer über die Erfahrung der Obdachlosigkeit praktisch verständigen und welcher Art das hierüber erzeugte Verständnis für die im öffentlichen Diskurs mit vielfältigen stigmatisierenden Zuschreibungen versehenen Obdachlosen ist. Dabei interessiert besonders, in Bezug auf welche Aspekte der Erfahrung von Obdachlosigkeit ein gemeinsames Verständnis möglich wird und an welchen Stellen dieses an Grenzen gerät. Dazu wurden die Gesprächsverläufe auf neun Stadtführungen mit (ehemaligen) obdachlosen Stadtführern unterschiedlicher Anbieter im deutschsprachigen Raum verschriftlicht und mit dem Verfahren der Dokumentarischen Methode ausgewertet. Die vergleichende Betrachtung der Verständigungspraxen eröffnet nicht zuletzt eine differenzierte Perspektive auf die in den Prozessen der Verständigung immer schon eingewobenen Anerkennungspraktiken. Mit Blick auf die moralische Debatte um organisierte Begegnungen mit sozialer Ungleichheit wird dadurch eine ethische Perspektive angeregt, in deren Zentrum Fragen zur Vermittlungsarbeit stehen.
High-mountain regions provide valuable ecosystem services, including food, water, and energy production, to more than 900 million people worldwide. Projections hold, that this population number will rapidly increase in the next decades, accompanied by a continued urbanisation of cities located in mountain valleys. One of the manifestations of this ongoing socio-economic change of mountain societies is a rise in settlement areas and transportation infrastructure while an increased power need fuels the construction of hydropower plants along rivers in the high-mountain regions of the world. However, physical processes governing the cryosphere of these regions are highly sensitive to changes in climate and a global warming will likely alter the conditions in the headwaters of high-mountain rivers. One of the potential implications of this change is an increase in frequency and magnitude of outburst floods – highly dynamic flows capable of carrying large amounts of water and sediments. Sudden outbursts from lakes formed behind natural dams are complex geomorphological processes and are often part of a hazard cascade. In contrast to other types of natural hazards in high-alpine areas, for example landslides or avalanches, outburst floods are highly infrequent. Therefore, observations and data describing for example the mode of outburst or the hydraulic properties of the downstream propagating flow are very limited, which is a major challenge in contemporary (glacial) lake outburst flood research. Although glacial lake outburst floods (GLOFs) and landslide-dammed lake outburst floods (LLOFs) are rare, a number of documented events caused high fatality counts and damage. The highest documented losses due to outburst floods since the start of the 20th century were induced by only a few high-discharge events. Thus, outburst floods can be a significant hazard to downvalley communities and infrastructure in high-mountain regions worldwide.
This thesis focuses on the Greater Himalayan region, a vast mountain belt stretching across 0.89 million km2. Although potentially hundreds of outburst floods have occurred there since the beginning of the 20th century, data on these events is still scarce. Projections of cryospheric change, including glacier-mass wastage and permafrost degradation, will likely result in an overall increase of the water volume stored in meltwater lakes as well as the destabilisation of mountain slopes in the Greater Himalayan region. Thus, the potential for outburst floods to affect the increasingly more densely populated valleys of this mountain belt is also likely to increase in the future. A prime example of one of these valleys is the Pokhara valley in Nepal, which is drained by the Seti Khola, a river crossing one of the steepest topographic gradients in the Himalayas. This valley is also home to Nepal’s second largest, rapidly growing city, Pokhara, which currently has a population of more than half a million people – some of which live in informal settlements within the floodplain of the Seti Khola. Although there is ample evidence for past outburst floods along this river in recent and historic times, these events have hardly been quantified.
The main motivation of my thesis is to address the data scarcity on past and potential future outburst floods in the Greater Himalayan region, both at a regional and at a local scale. For the former, I compiled an inventory of >3,000 moraine-dammed lakes, of which about 1% had a documented sudden failure in the past four decades. I used this data to test whether a number of predictors that have been widely applied in previous GLOF assessments are statistically relevant when estimating past GLOF susceptibility. For this, I set up four Bayesian multi-level logistic regression models, in which I explored the credibility of the predictors lake area, lake-area dynamics, lake elevation, parent-glacier-mass balance, and monsoonality. By using a hierarchical approach consisting of two levels, this probabilistic framework also allowed for spatial variability on GLOF susceptibility across the vast study area, which until now had not been considered in studies of this scale. The model results suggest that in the Nyainqentanglha and Eastern Himalayas – regions with strong negative glacier-mass balances – lakes have been more prone to release GLOFs than in regions with less negative or even stable glacier-mass balances. Similarly, larger lakes in larger catchments had, on average, a higher probability to have had a GLOF in the past four decades. Yet, monsoonality, lake elevation, and lake-area dynamics were more ambiguous. This challenges the credibility of a lake’s rapid growth in surface area as an indicator of a pending outburst; a metric that has been applied to regional GLOF assessments worldwide.
At a local scale, my thesis aims to overcome data scarcity concerning the flow characteristics of the catastrophic May 2012 flood along the Seti Khola, which caused 72 fatalities, as well as potentially much larger predecessors, which deposited >1 km³ of sediment in the Pokhara valley between the 12th and 14th century CE. To reconstruct peak discharges, flow depths, and flow velocities of the 2012 flood, I mapped the extents of flood sediments from RapidEye satellite imagery and used these as a proxy for inundation limits. To constrain the latter for the Mediaeval events, I utilised outcrops of slackwater deposits in the fills of tributary valleys. Using steady-state hydrodynamic modelling for a wide range of plausible scenarios, from meteorological (1,000 m³ s-1) to cataclysmic outburst floods (600,000 m³ s-1), I assessed the likely initial discharges of the recent and the Mediaeval floods based on the lowest mismatch between sedimentary evidence and simulated flood limits. One-dimensional HEC-RAS simulations suggest, that the 2012 flood most likely had a peak discharge of 3,700 m³ s-1 in the upper Seti Khola and attenuated to 500 m³ s-1 when arriving in Pokhara’s suburbs some 15 km downstream.
Simulations of flow in two-dimensions with orders of magnitude higher peak discharges in ANUGA show extensive backwater effects in the main tributary valleys. These backwater effects match the locations of slackwater deposits and, hence, attest for the flood character of Mediaeval sediment pulses. This thesis provides first quantitative proof for the hypothesis, that the latter were linked to earthquake-triggered outbursts of large former lakes in the headwaters of the Seti Khola – producing floods with peak discharges of >50,000 m³ s-1.
Building on this improved understanding of past floods along the Seti Khola, my thesis continues with an analysis of the impacts of potential future outburst floods on land cover, including built-up areas and infrastructure mapped from high-resolution satellite and OpenStreetMap data. HEC-RAS simulations of ten flood scenarios, with peak discharges ranging from 1,000 to 10,000 m³ s-1, show that the relative inundation hazard is highest in Pokhara’s north-western suburbs. There, the potential effects of hydraulic ponding upstream of narrow gorges might locally sustain higher flow depths. Yet, along this reach, informal settlements and gravel mining activities are close to the active channel. By tracing the construction dynamics in two of these potentially affected informal settlements on multi-temporal RapidEye, PlanetScope, and Google Earth imagery, I found that exposure increased locally between three- to twentyfold in just over a decade (2008 to 2021).
In conclusion, this thesis provides new quantitative insights into the past controls on the susceptibility of glacial lakes to sudden outburst at a regional scale and the flow dynamics of propagating flood waves released by past events at a local scale, which can aid future hazard assessments on transient scales in the Greater Himalayan region. My subsequent exploration of the impacts of potential future outburst floods to exposed infrastructure and (informal) settlements might provide valuable inputs to anticipatory assessments of multiple risks in the Pokhara valley.
Pokhara (ca. 850 m a.s.l.), Nepal's second-largest city, lies at the foot of the Higher Himalayas and has more than tripled its population in the past 3 decades. Construction materials are in high demand in rapidly expanding built-up areas, and several informal settlements cater to unregulated sand and gravel mining in the Pokhara Valley's main river, the Seti Khola. This river is fed by the Sabche glacier below Annapurna III (7555 m a.s.l.), some 35 km upstream of the city, and traverses one of the steepest topographic gradients in the Himalayas. In May 2012 a sudden flood caused >70 fatalities and intense damage along this river and rekindled concerns about flood risk management. We estimate the flow dynamics and inundation depths of flood scenarios using the hydrodynamic model HEC-RAS (Hydrologic Engineering Center’s River Analysis System). We simulate the potential impacts of peak discharges from 1000 to 10 000 m3 s−1 on land cover based on high-resolution Maxar satellite imagery and OpenStreetMap data (buildings and road network). We also trace the dynamics of two informal settlements near Kaseri and Yamdi with high potential flood impact from RapidEye, PlanetScope, and Google Earth imagery of the past 2 decades. Our hydrodynamic simulations highlight several sites of potential hydraulic ponding that would largely affect these informal settlements and sites of sand and gravel mining. These built-up areas grew between 3- and 20-fold, thus likely raising local flood exposure well beyond changes in flood hazard. Besides these drastic local changes, about 1 % of Pokhara's built-up urban area and essential rural road network is in the highest-hazard zones highlighted by our flood simulations. Our results stress the need to adapt early-warning strategies for locally differing hydrological and geomorphic conditions in this rapidly growing urban watershed.
Cosmic-ray neutron sensing (CRNS) is a non-invasive tool for measuring hydrogen pools such as soil moisture, snow or vegetation. The intrinsic integration over a radial hectare-scale footprint is a clear advantage for averaging out small-scale heterogeneity, but on the other hand the data may become hard to interpret in complex terrain with patchy land use.
This study presents a directional shielding approach to prevent neutrons from certain angles from being counted while counting neutrons entering the detector from other angles and explores its potential to gain a sharper horizontal view on the surrounding soil moisture distribution.
Using the Monte Carlo code URANOS (Ultra Rapid Neutron-Only Simulation), we modelled the effect of additional polyethylene shields on the horizontal field of view and assessed its impact on the epithermal count rate, propagated uncertainties and aggregation time.
The results demonstrate that directional CRNS measurements are strongly dominated by isotropic neutron transport, which dilutes the signal of the targeted direction especially from the far field. For typical count rates of customary CRNS stations, directional shielding of half-spaces could not lead to acceptable precision at a daily time resolution. However, the mere statistical distinction of two rates should be feasible.
Städte sind aufgrund ihrer Agglomeration von Bevölkerung, Sachwerten und Infrastrukturen in besonderem Maße von extremen Wetterereignissen wie Starkregen und Hitze betroffen. Zahlreiche Überflutungsereignisse infolge von Starkregen traten in den letzten Jahren in verschiedenen Regionen Deutschlands auf und führten nicht nur zu Schäden in zwei- bis dreistelliger Millionenhöhe, sondern auch zu Todesopfern. Und auch Hitzewellen, wie sie in den vergangenen Jahren vermehrt aufgetreten sind, bergen gesundheitliche Risiken, welche sich auch in verschiedenen Schätzungen zu Hitzetodesfällen wiederfinden.
Um diesen Risiken zu begegnen und Schäden infolge von Wetterextremen zu reduzieren, entwickeln viele Kommunen bereits Strategien und Konzepte im Kontext der Klimaanpassung und/oder setzen Anpassungsmaßnahmen um. Neben der Entwicklung und Umsetzung eigener Ideen orientieren sich Städte dabei u. a. an Leitfäden und Beispielen aus der Literatur, Erfahrungen aus anderen Städten oder an Ergebnissen aus Forschungsprojekten. Dieser Lern- und Transferprozess, der eine Übertragung von Maßnahmen oder Instrumenten der Klimaanpassung von einem Ort auf einen anderen beinhaltet, ist bislang noch unzureichend erforscht und verstanden.
Der vorliegende Bericht untersucht deshalb ebendiesen Lern- und Transferprozess zwischen sowie innerhalb von Städten sowie das Transferpotenzial konkreter Wissenstransfer-Medien, Instrumente und Maßnahmen. Damit wird das Ziel verfolgt, ein besseres Verständnis dieser Prozesse zu entwickeln und einen Beitrag zur Verbesserung des Transfers von kommunalen Klimaanpassungsaktivitäten zu leisten. Der vorliegende Inhalt baut dabei auf einer vorangegangenen Analyse des Forschungsstands zum Transfer von Policies durch Haupt et al. (2021) auf und versucht, den bereits generierten Wissensstand auf der Ebene von Policies nun um die Ebene konkreter Instrumente und Maßnahmen zu ergänzen sowie durch empirische Befunde zu ausgewählten Maßnahmen zu untermauern. Die Wissens- und Datengrundlage dieses Berichts umfasst einen Mix aus verschiedenen (Online)-Befragungen und Interviews mit Vertreter:innen relevanter Akteursgruppen, vor allem Vertreter:innen von Stadtverwaltungen, sowie den Erfahrungswerten der drei ExTrass-Fallstudienstädte Potsdam, Remscheid und Würzburg.
Nach einer Einleitung beschäftigt sich Kapitel 2 mit übergeordneten Faktoren der Übertragbarkeit bzw. des Transfers. Kapitel 2.1 bietet hierbei eine Zusammenfassung zum aktuellen Wissensstand hinsichtlich des Transfers von Policies im Bereich der städtischen Klimapolitik gemäß Haupt et al. (2021). Hier werden zentrale Kriterien für einen erfolgreichen Transfer herausgearbeitet, um einen Anknüpfungspunkt für die folgenden Inhalte und empirischen Befunde auf der Ebene konkreter Instrumente und Maßnahmen zu bieten. Kapitel 2.2 schließt hieran an und präsentiert Erkenntnisse aus einer weitreichenden Kommunalbefragung. Hierbei wurde untersucht ob und welche Klimaanpassungsmaßnahmen in den Städten bereits umgesetzt werden, welche fördernden und hemmenden Aspekte es dabei gibt und welche Erfahrungen beim Transfer von Wissen und Ideen bereits vorliegen.
Kapitel 3 untersucht die Rolle verschiedener Medien des Wissenstransfers und widmet sich dabei beispielhaft Leitfäden zur Klimaanpassung und Maßnahmensteckbriefen. Kapitel 3.1 beantwortet dabei Fragen nach der Relevanz und Zugänglichkeit von Leitfäden, deren Stärken und Schwächen, sowie konkreten Anforderungen vonseiten befragter Personen. Außerdem werden acht ausgewählte Leitfäden vorgestellt und komprimiert auf ihre Transferpotenziale hin eingeschätzt. Kapitel 3.2 betrachtet Maßnahmensteckbriefe als Medien des Wissenstransfers und arbeitet zentrale Aspekte für einen praxisrelevanten inhaltlichen Aufbau heraus, um basierend darauf einen Muster-Maßnahmensteckbrief für Klimaanpassungsmaßnahmen zu entwickeln und vorzuschlagen.
Kapitel 4 beschäftigt sich mit sehr konkreten kommunalen Erfahrungen rund um den Transfer von sieben ausgewählten Instrumenten und Maßnahmen und bietet zahlreiche empirische Befunde aus den Kommunen, basierend auf der Kommunalbefragung, verschiedenen Interviews und den Erfahrungen aus der Projektarbeit. Die folgenden sieben Instrumente und Maßnahmen wurden ausgewählt, um eine große Breite städtischer Klimaanpassungsaktivitäten zu betrachten: 1) Klimafunktionskarten (Stadtklimakarten), 2) Starkregengefahrenkarten, 3) Checklisten zur Klimaanpassung in der Bauleitplanung, 4) Verbot von Schottergärten in Bebauungsplänen, 5) Fassadenbegrünungen, 6) klimaangepasste Gestaltung von Grün- und Freiflächen sowie 7) Handlungsempfehlungen für Betreuungseinrichtungen zum Umgang mit Hitze und Starkregen. Für jede dieser Klimaanpassungsaktivitäten wird auf Ebene der Kommunen Ziel, Verbreitung und Erscheinungsformen, Umsetzung anhand konkreter Beispiele, fördernde und hemmende Faktoren sowievorliegende Erfahrungen zu und Hinweisen auf Transfer dargestellt.
Kapitel 5 schließt den vorliegenden Bericht ab, indem zentrale Transfer-Barrieren aus den gewonnenen Erkenntnissen aufgegriffen und entsprechende Empfehlungen an verschiedene Ebenen der Politik ausgesprochen werden. Diese Empfehlungen zur Verbesserung des Transfers von klimaanpassungsrelevanten Instrumenten, Strategien und Maßnahmen umfassen 1) die Verbesserung des Austauschs zwischen verschiedenen Städten, 2) die Verbesserung der Zugänglichkeit von Wissen und Erfahrungen, 3) die Schaffung von Vernetzungsstrukturen innerhalb von Städten sowie 4) bestehende Wissenslücken zu schließen.
Die Autor:innen des vorliegenden Berichts hoffen, durch die vielfältigen Untersuchungsaspekte einen Beitrag zum besseren Verständnis der Lern- und Transferprozesse und zur Verbesserung des Transfers kommunaler Klimaanpassungsaktivitäten zu leisten.
River floods are among the most devastating natural hazards worldwide. As their generation is highly dependent on climatic conditions, their magnitude and frequency are projected to be affected by future climate change. Therefore, it is crucial to study the ways in which a changing climate will, and already has, influenced flood generation, and thereby flood hazard. Additionally, it is important to understand how other human influences - specifically altered land cover - affect flood hazard at the catchment scale.
The ways in which flood generation is influenced by climatic and land cover conditions differ substantially in different regions. The spatial variability of these effects needs to be taken into account by using consistent datasets across large scales as well as applying methods that can reflect this heterogeneity. Therefore, in the first study of this cumulative thesis a complex network approach is used to find 10 clusters of similar flood behavior among 4390 catchments in the conterminous United States. By using a consistent set of 31 hydro-climatological and land cover variables, and training a separate Random Forest model for each of the clusters, the regional controls on flood magnitude trends between 1960-2010 are detected. It is shown that changes in rainfall are the most important drivers of these trends, while they are regionally controlled by land cover conditions.
While climate change is most commonly associated with flood magnitude trends, it has been shown to also influence flood timing. This can lead to trends in the size of the area across which floods occur simultaneously, the flood synchrony scale. The second study is an analysis of data from 3872 European streamflow gauges and shows that flood synchrony scales have increased in Western Europe and decreased in Eastern Europe. These changes are attributed to changes in flood generation, especially a decreasing relevance of snowmelt. Additionally, the analysis shows that both the absolute values and the trends of flood magnitudes and flood synchrony scales are positively correlated. If these trends persist in the future and are not accounted for, the combined increases of flood magnitudes and flood synchrony scales can exceed the capacities of disaster relief organizations and insurers.
Hazard cascades are an additional way through which climate change can influence different aspects of flood hazard. The 2019/2020 wildfires in Australia, which were preceded by an unprecedented drought and extinguished by extreme rainfall that led to local flooding, present an opportunity to study the effects of multiple preceding hazards on flood hazard. All these hazards are individually affected by climate change, additionally complicating the interactions within the cascade. By estimating and analyzing the burn severity, rainfall magnitude, soil erosion and stream turbidity in differently affected tributaries of the Manning River catchment, the third study shows that even low magnitude floods can pose a substantial hazard within a cascade.
This thesis shows that humanity is affecting flood hazard in multiple ways with spatially and temporarily varying consequences, many of which were previously neglected (e.g. flood synchrony scale, hazard cascades). To allow for informed decision making in risk management and climate change adaptation, it will be crucial to study these aspects across the globe and to project their trajectories into the future. The presented methods can depict the complex interactions of different flood drivers and their spatial variability, providing a basis for the assessment of future flood hazard changes. The role of land cover should be considered more in future flood risk modelling and management studies, while holistic, transferable frameworks for hazard cascade assessment will need to be designed.
Global heat adaptation among urban populations and its evolution under different climate futures
(2022)
Heat and increasing ambient temperatures under climate change represent a serious threat to human health in cities. Heat exposure has been studied extensively at a global scale. Studies comparing a defined temperature threshold with the future daytime temperature during a certain period of time, had concluded an increase in threat to human health. Such findings however do not explicitly account for possible changes in future human heat adaptation and might even overestimate heat exposure. Thus, heat adaptation and its development is still unclear. Human heat adaptation refers to the local temperature to which populations are adjusted to. It can be inferred from the lowest point of the U- or V-shaped heat-mortality relationship (HMR), the Minimum Mortality Temperature (MMT). While epidemiological studies inform on the MMT at the city scale for case studies, a general model applicable at the global scale to infer on temporal change in MMTs had not yet been realised. The conventional approach depends on data availability, their robustness, and on the access to daily mortality records at the city scale. Thorough analysis however must account for future changes in the MMT as heat adaptation happens partially passively. Human heat adaptation consists of two aspects: (1) the intensity of the heat hazard that is still tolerated by human populations, meaning the heat burden they can bear and (2) the wealth-induced technological, social and behavioural measures that can be employed to avoid heat exposure. The objective of this thesis is to investigate and quantify human heat adaptation among urban populations at a global scale under the current climate and to project future adaptation under climate change until the end of the century. To date, this has not yet been accomplished. The evaluation of global heat adaptation among urban populations and its evolution under climate change comprises three levels of analysis. First, using the example of Germany, the MMT is calculated at the city level by applying the conventional method. Second, this thesis compiles a data pool of 400 urban MMTs to develop and train a new model capable of estimating MMTs on the basis of physical and socio-economic city characteristics using multivariate non-linear multivariate regression. The MMT is successfully described as a function of the current climate, the topography and the socio-economic standard, independently of daily mortality data for cities around the world. The city-specific MMT estimates represents a measure of human heat adaptation among the urban population. In a final third analysis, the model to derive human heat adaptation was adjusted to be driven by projected climate and socio-economic variables for the future. This allowed for estimation of the MMT and its change for 3 820 cities worldwide for different combinations of climate trajectories and socio-economic pathways until 2100. The knowledge on the evolution of heat adaptation in the future is a novelty as mostly heat exposure and its future development had been researched. In this work, changes in heat adaptation and exposure were analysed jointly. A wide range of possible health-related outcomes up to 2100 was the result, of which two scenarios with the highest socio-economic developments but opposing strong warming levels were highlighted for comparison. Strong economic growth based upon fossil fuel exploitation is associated with a high gain in heat adaptation, but may not be able to compensate for the associated negative health effects due to increased heat exposure in 30% to 40% of the cities investigated caused by severe climate change. A slightly less strong, but sustainable growth brings moderate gains in heat adaptation but a lower heat exposure and exposure reductions in 80% to 84% of the cities in terms of frequency (number of days exceeding the MMT) and intensity (magnitude of the MMT exceedance) due to a milder global warming. Choosing a 2 ° C compatible development by 2100 would therefore lower the risk of heat-related mortality at the end of the century. In summary, this thesis makes diverse and multidisciplinary contributions to a deeper understanding of human adaptation to heat under the current and the future climate. It is one of the first studies to carry out a systematic and statistical analysis of urban characteristics which are useful as MMT drivers to establish a generalised model of human heat adaptation, applicable at the global level. A broad range of possible heat-related health options for various future scenarios was shown for the first time. This work is of relevance for the assessment of heat-health impacts in regions where mortality data are not accessible or missing. The results are useful for health care planning at the meso- and macro-level and to urban- and climate change adaptation planning. Lastly, beyond having met the posed objective, this thesis advances research towards a global future impact assessment of heat on human health by providing an alternative method of MMT estimation, that is spatially and temporally flexible in its application.
Die Gesellschaft befindet sich längst in einem digitalen Transformationsprozess. Alle gesellschaftlichen Bereiche verändern sich. Man spricht von einer Kultur der Digitalität, die den Leitmedienwechsel vom gedruckten Buch hin zum vernetzten digitalen Endgerät beschreibt. Auch die Institution „Schule“ muss sich diesem Wandel öffnen. Einen wesentlichen Schritt stellt das Strategiepapier der Kultusministerkonferenz „Bildung in der digitalen Welt“ aus dem Jahr 2017 dar. Darin legt sie die wesentlichen Handlungsfelder zu einem digitalen Wandel fest und erweitert den Bildungsauftrag um die „Kompetenzen in der digitalen Welt“.
Das sog. SAMR-Modell stellt dabei ein geeignetes Umsetzungs- und Reflektionswerkzeug für den Einsatz digitaler Medien dar. Es strukturiert den Einsatz auf vier Stufen. Die beiden unteren Stufen (Substitution und Augmentation) schreiben der Art und Weise, wie die digitalen Medien genutzt werden, eine Ersatz- oder Verbesserungsfunktion des analogen Lernwerkzeuges zu. Ziel des Modells ist es aber, mithilfe hinzugewonnener digitaler Möglichkeiten, Lernen neu zu gestalten. Da das Modell aus den USA stammt, weist es weder direkten Bezüge zum Strategiepapier der Kultusministerkonferenz noch zu den Bildungsstandards der Geographie auf.
Diese wissenschaftliche Arbeit stellt diese Bezüge her. Ziel ist es, auf der Grundlage des SAMR-Modells ein Handlungskonzept für Geographielehrkräfte zu entwickeln. Es zeigt auf, wie sie sowohl fachliche Kompetenzen als auch Kompetenzen in der digitalen Welt systematisch bei den Lernenden fördern können.
The study examined the potential future changes of drought characteristics in the Greater Lake Malawi Basin in Southeast Africa. This region strongly depends on water resources to generate electricity and food. Future projections (considering both moderate and high emission scenarios) of temperature and precipitation from an ensemble of 16 bias-corrected climate model combinations were blended with a scenario-neutral response surface approach to analyses changes in: (i) the meteorological conditions, (ii) the meteorological water balance, and (iii) selected drought characteristics such as drought intensity, drought months, and drought events, which were derived from the Standardized Precipitation and Evapotranspiration Index. Changes were analyzed for a near-term (2021–2050) and far-term period (2071–2100) with reference to 1976–2005. The effect of bias-correction (i.e., empirical quantile mapping) on the ability of the climate model ensemble to reproduce observed drought characteristics as compared to raw climate projections was also investigated. Results suggest that the bias-correction improves the climate models in terms of reproducing temperature and precipitation statistics but not drought characteristics. Still, despite the differences in the internal structures and uncertainties that exist among the climate models, they all agree on an increase of meteorological droughts in the future in terms of higher drought intensity and longer events. Drought intensity is projected to increase between +25 and +50% during 2021–2050 and between +131 and +388% during 2071–2100. This translates into +3 to +5, and +7 to +8 more drought months per year during both periods, respectively. With longer lasting drought events, the number of drought events decreases. Projected droughts based on the high emission scenario are 1.7 times more severe than droughts based on the moderate scenario. That means that droughts in this region will likely become more severe in the coming decades. Despite the inherent high uncertainties of climate projections, the results provide a basis in planning and (water-)managing activities for climate change adaptation measures in Malawi. This is of particular relevance for water management issues referring hydro power generation and food production, both for rain-fed and irrigated agriculture.
The estimation of financial losses is an integral part of flood risk assessment. The application of existing flood loss models on locations or events different from the ones used to train the models has led to low performance, showing that characteristics of the flood damaging process have not been sufficiently well represented yet. To improve flood loss model transferability, I explore various model structures aiming at incorporating different (inland water) flood types and pathways. That is based on a large survey dataset of approximately 6000 flood-affected households which addresses several aspects of the flood event, not only the hazard characteristics but also information on the affected building, socioeconomic factors, the household's preparedness level, early warning, and impacts. Moreover, the dataset reports the coincidence of different flood pathways. Whilst flood types are a classification of flood events reflecting their generating process (e.g. fluvial, pluvial), flood pathways represent the route the water takes to reach the receptors (e.g. buildings). In this work, the following flood pathways are considered: levee breaches, river floods, surface water floods, and groundwater floods.
The coincidence of several hazard processes at the same time and place characterises a compound event. In fact, many flood events develop through several pathways, such as the ones addressed in the survey dataset used. Earlier loss models, although developed with one or multiple predictor variables, commonly use loss data from a single flood event which is attributed to a single flood type, disregarding specific flood pathways or the coincidence of multiple pathways. This gap is addressed by this thesis through the following research questions: 1. In which aspects do flood pathways of the same (compound inland) flood event differ? 2. How much do factors which contribute to the overall flood loss in a building differ in various settings, specifically across different flood pathways? 3. How well can Bayesian loss models learn from different settings? 4. Do compound, that is, coinciding flood pathways result in higher losses than a single pathway, and what does the outcome imply for future loss modelling?
Statistical analysis has found that households affected by different flood pathways also show, in general, differing characteristics of the affected building, preparedness, and early warning, besides the hazard characteristics. Forecasting and early warning capabilities and the preparedness of the population are dominated by the general flood type, but characteristics of the hazard at the object-level, the impacts, and the recovery are more related to specific flood pathways, indicating that risk communication and loss models could benefit from the inclusion of flood-pathway-specific information.
For the development of the loss model, several potentially relevant predictors are analysed: water depth, duration, velocity, contamination, early warning lead time, perceived knowledge about self-protection, warning information, warning source, gap between warning and action, emergency measures, implementation of property-level precautionary measures (PLPMs), perceived efficacy of PLPMs, previous flood experience, awareness of flood risk, ownership, building type, number of flats, building quality, building value, house/flat area, building area, cellar, age, household size, number of children, number of elderly residents, income class, socioeconomic status, and insurance against floods. After a variable selection, descriptors of the hazard, building, and preparedness were deemed significant, namely: water depth, contamination, duration, velocity, building area, building quality, cellar, PLPMs, perceived efficacy of PLPMs, emergency measures, insurance, and previous flood experience. The inclusion of the indicators of preparedness is relevant, as they are rarely involved in loss datasets and in loss modelling, although previous studies have shown their potential in reducing losses. In addition, the linear model fit indicates that the explanatory factors are, in several cases, differently relevant across flood pathways.
Next, Bayesian multilevel models were trained, which intrinsically incorporate uncertainties and allow for partial pooling (i.e. different groups of data, such as households affected by different flood pathways, can learn from each other), increasing the statistical power of the model. A new variable selection was performed for this new model approach, reducing the number of predictors from twelve to seven variables but keeping factors of the hazard, building, and preparedness, namely: water depth, contamination, duration, building area, PLPMs, insurance, and previous flood experience. The new model was trained not only across flood pathways but also across regions of Germany, divided according to general socioeconomic factors and insurance policies, and across flood events. The distinction across regions and flood events did not improve loss modelling and led to a large overlap of regression coefficients, with no clear trend or pattern. The distinction of flood pathways showed credibly distinct regression coefficients, leading to a better understanding of flood loss modelling and indicating one potential reason why model transferability has been challenging.
Finally, new model structures were trained to include the possibility of compound inland floods (i.e. when multiple flood pathways coincide on the same affected asset). The dataset does not allow for verifying in which sequence the flood pathway waves occurred and predictor variables reflect only their mixed or combined outcome. Thus, two Bayesian models were trained: 1. a multi-membership model, a structure which learns the regression coefficients for multiple flood pathways at the same time, and 2. a multilevel model wherein the combination of coinciding flood pathways makes individual categories. The multi-membership model resulted in credibly different coefficients across flood pathways but did not improve model performance in comparison to the model assuming only a single dominant flood pathway. The model with combined categories signals an increase in impacts after compound floods, but due to the uncertainty in model coefficients and estimates, it is not possible to ascertain such an increase as credible. That is, with the current level of uncertainty in differentiating the flood pathways, the loss estimates are not credibly distinct from individual flood pathways.
To overcome the challenges faced, non-linear or mixed models could be explored in the future. Interactions, moderation, and mediation effects, as well as non-linear effects, should also be further studied. Loss data collection should regularly include preparedness indicators, and either data collection or hydraulic modelling should focus on the distinction of coinciding flood pathways, which could inform loss models and further improve estimates. Flood pathways show distinct (financial) impacts, and their inclusion in loss modelling proves relevant, for it helps in clarifying the different contribution of influencing factors to the final loss, improving understanding of the damaging process, and indicating future lines of research.