No description available.

Flood risk analysis is now fundamental to ood management decision making. It relies on the use of computer models to estimate ood depths for given hydrological conditions. The correct calculation of risks associated with di erent management options requires that the uncertainty in the computer model output is carefully estimated. There are several sources of uncertainty in flood models, including structural uncertainties in the model representation of reality, uncertainty in model parameters, and observation errors. We refer to the rst of these as "model inadequacy". The work described in this thesis concerns the calibration of computer models to describe fluvial flooding, taking into account model inadequacy and paying particular attention to the requirements of risk analysis calculations. A methodology which has had some success in other application areas is Bayesian model calibration, using Gaussian process representation both for the error arising from model inadequacy, and to emulate the computer model output. The e ectiveness of this methodology is demonstrated for steady state flood models, both of a series of laboratory experiments, and of a historical ood using a satellite image of flood outline for calibration. Extension of the methodology to calibration of dynamic models using gauged data is not straightforward, but is achieved for flood models by means of an emulator, which replaces the computationally expensive hydrodynamic model with a time-dependent transfer function. This permits calibrated prediction of floods using historical gauged data, both in the existing channel and after modelling potential modi cations to the channel. It is shown that calibration without inclusion of a model inadequacy function cannot match measured data. Finally, application of the methodology is demonstrated in the context of a calculation of probability of inundation in the channel, both with and without modi cation.

This thesis investigates the nature of grant-aided flood management strategies for watercourses approved in England and Scotland between 1994 and 2004. A database of 595 grant-aided fluvial flood management strategies was established to classify the character of practice over this period. The presence or absence of 119 distinct measures of practice were placed in 10 Groups (e. g. Walls, Attenuation or Non- Structural), and used with cluster analysis to identify three types of practice: those relating to structural barriers, pumping stations and modifications to the channel. Structural measures dominated the database. Multivariate statistical analyses (principal components analysis, chi-squared tests and discriminant analysis) were used to quantify the main operational drivers upon practice. New associations were found between the presence or absence of Groups of practices and the nature of existing flood management activities, environmental designations, standard of protection, operating authority type and, most significantly, catchment characteristics. Catchment slope, size, urbanisation, base flow and wetness characteristics were found by discriminant analysis to be able to correctly predict the type of strategy in nearly 60% of cases, illustrating the degree of influence exerted by physical factors. Spatial and temporal patterns were examined. Regional patterns in flood management practice were influenced by catchment characteristics and the type of operating authority responsible. Strategies in Scotland were designed to a higher standard of protection and were proportionally more likely to involve Attenuation or Adaptation measures than their English counterparts. Invasive techniques such as those to increase conveyance, or those involving inchannel construction, decreased in frequency of implementation. Non-Structural measures and those deemed as Adaptation saw an increase in adoption over the 10- year period. Through investigation of a small sample of rejected alternatives, a rise in the appraisal of land use modifications was observed. These results illustrate a shift away from structural dominance, in line with calls for sustainable flood management.

Using the Conservation of Resources model by Hobfoll (1989,1998) and the Cognitive- Appraisal theory by Lazarus and Folkman (1984) this research sought to understand what role resources and appraisal had in a participant's experience of loss and coping in Northamptonshire or Yorkshire due to being flood affected. Samples from two UK floods, the Easter 1998 and Autumn 2000 events, were selected and twenty-four in-depth interviews, one case study and two focus groups were conducted using a qualitative methodological approach and one semi-qualitative questionnaire was developed and distributed to 250 properties. The research aimed to establish which authors work was more appropriate towards understanding an individual's experience of flooding and any subsequent loss or was it better to combine the two. Then to understand if a single resource could contain both an objective and a subjective component that could be lost as a result of a flood. If this last aim was supported, then two further objectives were to be investigated; If a single resource contained dual components, did the objective or subjective element of the loss have the greater impact upon the individual. Finally, if a single resource contained dual components, how did the individual cope with loss of the objective element compared to loss of the subjective element? This research concluded that it was more appropriate to combine both theories to provide a comprehensive understanding of flooding. The five resources categories, object, condition, personal characteristic, energy and social support all demonstrated to varying degrees a duality of loss, in that one resource could have both an objective and subjective element that could be lost. Both types of loss had an impact but subjective losses appeared to affect participants longer. Participants used problem-solving, emotion-focused and disengagement-focused coping activities but there was a weak pattern of loss to coping employed.

The urbanisation process in Malaysia is growing rapidly as in most of the developing countries in the world. Urbanisation is the key engine that generates economic and social advancement: therefore efficient and productive cities or towns are necessary for national economic growth and welfare. The on-going rapid urbanisation process in Malaysia, however, has exacerbated processes of environmental degradation and has contributed to problems of flooding. This study discusses the contemporary academic debates in the fields of social vulnerability, social capital and adaptation, and hazard management with a focus on flood risk management in low-income settlements in Kuala Lumpur. These are some of the key issues for the city as the management of urban environment in Malaysia must be able to guarantee not only good development and planning practice but also needs to ensure that the necessary precautions and disaster strategies are in place for any eventualities. The study attempts to highlight the affected communities’ vulnerability to environmental hazards, flood risk communication and management, all of which represent critical urban management issues in the rapidly expanding city. Respondents participating in this study include several low-income squatter communities in Kuala Lumpur, officials from government agencies involved in flood risk management as well as community leaders and politicians. The study examines how the affected communities understand their vulnerability and their responses, and investigates the strategies adopted by the government agencies in addressing flood issues and in dealing with the victims of the recurring floodings.

Despite 'modern' construction and management techniques, flood embankment and embankment dam failures occur almost routinely around the world. The need to understand, predict and prevent the breaching process remains a high priority for owners and flood risk managers alike. This research provides new understanding and improved methods for predicting breach initiation and growth through earth flood embankments or dams. The improvement of breach model accuracy has made slow progress over the past 20 years, with confusion around breaching processes arising from a lack of appreciation of soil mechanics interacting with hydraulics and structural behaviour. The prediction of different breach processes requires the integration of techniques from all three disciplines. This thesis makes advances from earlier work (Mohamed, 2002) to produce a predictive breach model intended for industry application. The research develops improved approaches for flow calculation, sediment erosion and structural response for predicting breach initiation and growth and uses field data, including video footage, from the EU IMP ACT project and large scale test and case study data from collaboration with the International Dam Safety Interest Group breach modelling project.

Coastal Partnerships (CPs) have emerged since the early 1990s as a local and regional response to the national coastal management policy vacuum in the United Kingdom (UK). CPs are voluntary groupings of stakeholders aspiring to improved coastal resource use through integrated coastal management (ICM). CPs use the rationale of deliberative consensus building to develop and implement multi-sectoral coastal management strategies to deliver ICM. Despite the significance of CPs, there has been a lack of research into their effectiveness in securing meaningful representation of stakeholder views in decision-making. Poor stakeholder representation has the potential to undermine the credibility, legitimacy, accountability and democratic basis of CP management outputs. Through a telephone interview schedule with CP officers in the UK, the procedures and safeguards in place to accommodate stakeholder representation were evaluated. Results indicated that CPs have restrictive and variable membership criteria and unclear decision making procedures. These limitations exposed CPs to poor inclusivity and served to maintain existing power relations amongs stakeholders. It was also apparent that CPs had little information concerning the legitimacy of those representing stakeholder constituencies, potentially risking exposure to misrepresentattion. In order to examine these issues further, four case study CPs were selected and a personal interview schedule undertaken with stakeholder representatives. It was found that representatives were, in general the legitimate representative of their constituency, that most held a trustee relationship with their constituency, but generally had limited accountability - both individually and collectively. Representatives perceived the decision-making process of CPs to favour already powerful groups, which served to limit the credibility of the CP amongst the membership. The concept of secure representation was developed to describe circumstances in which stakeholder representation could be assured. It was determined that secure representation occurred when representatives were responsive to their constituency, when CPs had an inclusive membership and when decision-making was fair to all involved. Specific internal and external management measures to deliver secure representation were defined. This facilitated the development of a conceptual model that mapped secure representation against specific management measures. The model allowed particular routes to be identified for CPs to enhance their secure representation. It was concluded that both the procedures and safeguards within CPs and the management measures within stakeholder constituencies required reform. Central to this reform was the need for CPs to extend their sphere of influence to enhance the representation of stakeholder constituencies within coastal decision-making

Die Broschüre vermittelt anschaulich, was von Gemeinden, Grundeigentümern, Bewirtschaftern und anderen Betroffenen auf lokaler Ebene unternommen werden kann, um Schäden durch Hochwasser vorzubeugen. Diskutiert werden Maßnahmen wie Flächenentsiegelung, angepasste Landwirtschaft, der Ausbau von Rückhaltebecken oder verbesserte Teichnutzungen. Erfolgreiche Beispiele aus der Praxis runden die Handlungsempfehlungen ab.

Wald weist gegenüber anderen Landnutzungen meist die günstigeren Wasserrückhalteigenschaften auf. Diese sind jedoch begrenzt. Ob zusätzlicher Wald in einem Einzugsgebiet zur Reduktion eines Hochwassers führt, hängt ab von der Vorwitterung, den Eigenschaften des Bodens, auf dem die Aufforstung etabliert wurde, Dauer und Intensität des hochwasserauslösenden Niederschlagsereignisses und Lage und Größe der Aufforstungsfläche im betrachteten Einzugsgebiet. Weiterhin spielt das Waldmanagement, welches in dieser Arbeit nur am Rande diskutiert wurde, eine bedeutende Rolle. Bei der Umwandlung einer anderen Landnutzung in Wald sind noch nicht alle Prozesse, die den Wasserrückhalt betreffen, ausreichend untersucht und beschrieben. Dies gilt besonders für die Änderungen in der hydraulischen Architektur der Böden. Es wurde dargestellt, dass aufwachsende Wälder schon nach wenigen Jahren die Porenverteilung besonders in den oberen Bodenhorizonten verändern. Obwohl experimentelle Felduntersuchungen besonders durch die Suche nach geeigneten Teststandorten schwierig sind, wären weitere Messergebnisse von anderen Böden mit anderen Baumarten hier wünschenswert. Eine modellhafte Beschreibung einer Landnutzungsänderung hin zu Wald in Bezug auf den Hochwasserrückhalt ist demnach mit hohen Unsicherheiten behaftet. Modelle bleiben dennoch die einzige Möglichkeit, Auswirkungen von Landnutzungsänderungen mit vertretbarem Aufwand quantifizierend abzuschätzen. Allgemein gilt bei der Anwendung hydrologischer Modelle zur Prognose von Auswirkungen veränderter Landnutzungen, dass bislang wenig quantitativ verwertbares Wissen über Änderungen im Boden besteht. Weder der Zielzustand noch der Verlauf der Transformation können hier sicher prognostiziert werden. Vernachlässigt man aber solche Prozesse, dürfen bei einer Ergebnisdiskussion auch nur die berücksichtigten Prozesse angeführt werden. Die Weiterentwicklung der Modelle mit gezielter paralleler Datenerhebung ist hier unabdingbar. Die zunehmenden Fragestellungen hinsichtlich veränderter Landnutzungssysteme erfordern auch innovative Formen der Parametrisierung und Kalibrierung der Modelle. Der zunehmende Grad an Prozessabbildungen in den Modellen darf die Parametrisierbarkeit nicht unmöglich machen. Eine adäquate Prozessabbildung ist jedoch der Schlüssel für die szenarienfähige Modellierung. Die Kommunikation der Ergebnisse muss deshalb eine hohe Transparenz mit der Benennung aller bekannten Unsicherheiten aufweisen, da Entscheidungen in der Landnutzung Konsequenzen über sehr lange Zeiträume hinweg nach sich ziehen. Die qualifizierte Prognose von Landnutzungsänderungen ist eine disziplinübergreifende Aufgabe. Hier wirken soziologische, ökonomische und ökologische Prozesse zusammen, deren Resultat die zukünftige Landnutzung ist. Eine weitere wichtige Schlussfolgerung der vorliegenden Arbeit ist daher, dass für die Umsetzung von Maßnahmen, zur Erhöhung des Wasserrückhaltes, wie hier der Aufforstung, ein breiter wissenschaftlicher und gesellschaftlicher Konsens herrschen muss. Es braucht integrierte Ansätze zur disziplinübergreifenden Beschreibung von Auswirkungen veränderter Landnutzung. Trotz aller Unsicherheiten bei der wissenschaftlichen Beweisführung wird erwartet, dass bis zur Umsetzung der Hochwasserrisiko-Managementpläne „nachhaltige Flächennutzungen“ zur „Verbesserung des Wasserrückhaltes“ definiert sind. Besonders für die politischen Entscheidungsträger ist zur Entwicklung geeigneter Steuerelemente festzuhalten, das Hochwasserschutzmaßnahmen in der Fläche ihre hauptsächliche Wirkung nicht am Punkt der Implementierung entfalten, sondern erst weiter flussabwärts. Daher sind die bisherigen Förderinstrumente der EU-Agrarflächenförderung für den Hochwasserschutz in der Fläche nahezu nicht anwendbar. Es gilt hier sektorales Denken zu überwinden. Unterschiedliche Ansprüche an Landnutzungssysteme sind durch Lösungsansätze auszubalancieren, die die unterschiedlichen Landschaftsfunktionen berücksichtigen, von denen Wasserrückhalt ein Teil sein kann. Andere Schutzziele wie Naturschutz, Bodenschutz, Ziele der Wasserrahmenrichtlinie, Fragen eines ästhetischen Landschaftsbildes und nicht zuletzt Fragen der wirtschaftlichen Ansprüche an die einzelnen Flächen spielen hier eine wichtige Rolle. Bei der Entwicklung begründeter Zukunftsszenarien ist diese transdisziplinäre Herangehensweise unbedingt zu empfehlen. Hochwasserschutz kann aber nicht die Aufgabe haben, Hochwasserereignisse vollkommen auszuschließen. Schon heute ist bekannt, dass das Ausbleiben kleiner und mittlerer Hochwässer ökologische Konsequenzen hat. Vielmehr könnte in Gebieten, wie dem hier untersuchten, eine Erhöhung des Waldanteils dazu beitragen, die anthropogenen Störungen zu reduzieren und den Wasserrückhalt dahingehend zu erhöhen, dass hochwasserverschärfende Eingriffe in den Einzugsgebieten zurückgebaut werden.:Inhalt Erklärung des Promovenden 3 Danksagung 4 1 Einführung 6 1.1 Hintergrund und Motivation 6 1.2 Zielsetzung 8 1.3 Struktur 9 2 Zusammenfassende Darstellung der Publikationsinhalte 11 2.1 Vorstellung des Modells AKWA-M® 11 2.2 Einfluss des Waldes auf bodenhydraulische Eigenschaften 12 2.3 Bildung begründeter Waldmehrungsszenarien 13 2.4 Exkurs: Politischer Vollzug in sächsischen Hochwasserentstehungsgebieten 14 2.5 Synthese 15 3 Schlussfolgerungen 16 4 Literatur 18 Anhänge: Anhang 1: WAHREN A., SCHWÄRZEL K., FEGER K.H., MÜNCH A., DITTRICH I. (2007): Identification and model based assessment of the potential water retention caused by land-use changes, Advances in Geosciences 11: 49–56. Anhang 2: WAHREN A., SCHWÄRZEL K., FEGER K.H., MÜNCH A. (2009): Land-use effects on flood generation – considering soil hydraulic measurements in modelling, Advances in Geosciences 21: 99–107. Anhang 3: WAHREN A., FEGER K.H. (2010): Model-Based Assessment of Forest Land Management on Water Dynamics at Various Hydrological Scales – A Case Study, in: Bredemeier, M.; Cohen, S.; Godbold, D.L.; Lode, E.; Pichler, V.; Schleppi, P. (Eds.): Forest Management and the Water Cycle - An Ecosystem-Based Approach, Ecological Studies 212, Springer: 453-469 Anhang 4: WAHREN A., FRANK S., WALTHER P., SCHMIDT W., FEGER K.H. (2011): Erstellung eines Leitfadens für Ausgleichsmaßnahmen auf landwirtschaftlich genutzten Flächen in den Hochwasserentstehungsgebieten Sachsens, Hydrologie und Wasserbewirtschaftung 55: 155-165. Anhang 5: WAHREN A., SCHWÄRZEL K., FEGER K.H. (2012): Potentials and limitations of natural flood retention by forested land in headwater catchments: evidence from experimental and model studies, J. Flood Risk Management 5, 321–335. / Forests show, compared to other land uses, in many cases good water retention potential. This is however limited. Whether additional forest area in a catchment leads to a reduction of flooding depends on the pre-event atmospheric conditions, the soil characteristics at the afforested site, the duration and intensity of the rain storm event, and location and size of the afforested area. Further, the forest management, which is only briefly discussed in this thesis, plays an important role. Many water retention related processes occurring during the transformation of a landuse into forest are not yet sufficiently investigated an described. This applies especially to the changes in the hydraulic architecture of the soil. It was shown that after a few years growing forests have already changed the pore distribution, especially in the upper soil horizons. However, further research under different soil and tree type would be desirable. Therefore, a model-based description of land use change towards forest with regard to flood retention comprises uncertainties which should be taken into consideration. Nevertheless, models are the only possibility to assess land use change effects with justifiable expenditure. In general, the application of hydrological models comprised sparse useful information about changes in the soil due to a changed land use. Neither the target state nor the progression of the transformation can be predicted with certainty. Further development of models with parallel observations and data gathering is essential. With increasing number of questions regarding modified land use systems, a need arises for innovative forms of parameterisation and model calibration. The increasing degree of process mapping in models may make parameterability difficult, however, adequate process mapping is the key to scenario capable modelling. The communication of results must therefore include a high degree of transparency in the definition of all known uncertainties, because decisions have long lasting consequences. A qualified prediction of land use changes is a cross-disciplinary task. Ecological, economical, and sociological processes together form the future land use distribution. An important conclusion from this thesis is that the implementation of measures targeting increased water retention requires must result in a consensus with society and economics. Integrated approaches and transdisciplinary assessment of impacts of land use modifications are needed. Although, the uncertainties in model-based land use change assessment are high, there is a need for the definition of “sustainable land use” and “increase of water retention” for the flood risk management plans. Adapted land use as a component of integrated flood risk management has a major constraint: the benefits of water retention in the landscape are mostly not directly noticeable at the place where a measure is implemented. This is highly important for stakeholders and decision makers. However, given that most of the land available for afforestation is a private property, it may be necessary to provide subsidies to encourage landowners to increase the percentage of forested land. Competitive land use system requirements need to be balanced with approaches dealing with different landscape functions. Water retention is part of this functioning. Other protection aims like nature protection, soil protection, aims of the Water Framework Directive, aesthetic land use pattern but also the agrar-economic production play an important role. Well-founded future land use scenarios should use this transdisciplinary view. Finally, it is also important to keep in mind that floods belong to a healthy river runoff regime. Floods are an important part of the natural hydrological cycle, and therefore the goal of watershed management should not be to eliminate them entirely. Additional forest can help to re-establish the natural water retention potential in anthropogenically disturbed river basins and to decrease the human-made contribution to flood generation.:Inhalt Erklärung des Promovenden 3 Danksagung 4 1 Einführung 6 1.1 Hintergrund und Motivation 6 1.2 Zielsetzung 8 1.3 Struktur 9 2 Zusammenfassende Darstellung der Publikationsinhalte 11 2.1 Vorstellung des Modells AKWA-M® 11 2.2 Einfluss des Waldes auf bodenhydraulische Eigenschaften 12 2.3 Bildung begründeter Waldmehrungsszenarien 13 2.4 Exkurs: Politischer Vollzug in sächsischen Hochwasserentstehungsgebieten 14 2.5 Synthese 15 3 Schlussfolgerungen 16 4 Literatur 18 Anhänge: Anhang 1: WAHREN A., SCHWÄRZEL K., FEGER K.H., MÜNCH A., DITTRICH I. (2007): Identification and model based assessment of the potential water retention caused by land-use changes, Advances in Geosciences 11: 49–56. Anhang 2: WAHREN A., SCHWÄRZEL K., FEGER K.H., MÜNCH A. (2009): Land-use effects on flood generation – considering soil hydraulic measurements in modelling, Advances in Geosciences 21: 99–107. Anhang 3: WAHREN A., FEGER K.H. (2010): Model-Based Assessment of Forest Land Management on Water Dynamics at Various Hydrological Scales – A Case Study, in: Bredemeier, M.; Cohen, S.; Godbold, D.L.; Lode, E.; Pichler, V.; Schleppi, P. (Eds.): Forest Management and the Water Cycle - An Ecosystem-Based Approach, Ecological Studies 212, Springer: 453-469 Anhang 4: WAHREN A., FRANK S., WALTHER P., SCHMIDT W., FEGER K.H. (2011): Erstellung eines Leitfadens für Ausgleichsmaßnahmen auf landwirtschaftlich genutzten Flächen in den Hochwasserentstehungsgebieten Sachsens, Hydrologie und Wasserbewirtschaftung 55: 155-165. Anhang 5: WAHREN A., SCHWÄRZEL K., FEGER K.H. (2012): Potentials and limitations of natural flood retention by forested land in headwater catchments: evidence from experimental and model studies, J. Flood Risk Management 5, 321–335.

Die Broschüre vermittelt anschaulich, was von Gemeinden, Grundeigentümern, Bewirtschaftern und anderen Betroffenen auf lokaler Ebene unternommen werden kann, um Schäden durch Hochwasser vorzubeugen. Diskutiert werden Maßnahmen wie Flächenentsiegelung, angepasste Landwirtschaft, der Ausbau von Rückhaltebecken oder verbesserte Teichnutzungen. Erfolgreiche Beispiele aus der Praxis runden die Handlungsempfehlungen ab.