Decision-making under uncertainty in model-based water management : The science-practice interface

Balancing the different needs and demands of water users and managing the supply side under temporal and spatial variability and extremes has always been a challenging task for water managers. However, accelerated environmental and societal change aggravates water management as uncertainties increase even further. Decision-making in water management must integrate uncertainty information to base decisions on and be prepared for surprise and ambiguity. While it is often considered that decision-makers do not understand or – at least sometimes – ignore uncertainty analysis, this research shows that uncertainties do in fact matter for water managers and that they already cope with them and acknowledge them as an integral part of their planning. This doctoral research aims at improving the understanding of how scientific uncertainties find better integration into planning and decision-making processes in model-based water management. The thesis hereby follows the hypothesis that understanding and identifying the plurality of practitioners and the diversity of their approaches, perspectives, and reasoning are key aspects to close the science-practice gap. Extensive expert elicitation, a quantitative survey and qualitative system modelling present the applied methods to answer the research questions. The intensive engagement with practitioners plays a crucial role for the thesis to assess uncertainty perception and handling strategies of water managers. Even though the results are mainly demonstrated at the case of reservoir management under changing intra-annual and annual conditions, the findings can easily be transferred to other water-related management objectives. The main finding of this research is that water managers acknowledge uncertainties. However, the degree of acknowledgement and handling capacity varies per level of working experience, educational background, type of employer and affiliation to business unit. In close relation to their background, water managers have developed different strategies to handle uncertainties, approaches which may seem less obvious to scientists. Additionally, tacit knowledge plays a major role in handling uncertainties as well as the implicit handling of process uncertainties. A lack of transparency, regulations and constraints in a highly politicized decision-making environment present limitations of uncertainty integration. Thus, the use of uncertainty strategies and routines applied by the practitioners differs regarding group membership and time-frame of the management objective. In the course of this doctoral thesis, three major tools were developed to increase the transparency and integration of uncertainties: 1) a 2x2 uncertainty matrix, 2) an integration and analytical framework, and 3) a qualitative system model. This compilation has identified criteria, described prerequisites and provided a practical strategy to improve the integration of scientific uncertainties into planning and decision-making processes in model-based water management. It gives implications for increasing usability of uncertainty information and enables second or third loop learning for adaptive or transformative water management by fostering cross-communication within practice and between science and practice. This research also presents a theoretical construct to rethink uncertainty implications and their interrelations with respect to a plurality of perspectives, especially, regarding the diversity of practitioners. Furthermore, this research contributed to the science-practice gap research by emphasising the plurality of practitioners' uncertainty perception and handling. Acknowledging this plurality overcomes the thinking of a linear causal chain of information and makes room for a plurality of knowing and, hence, different ways to cope with and to integrate uncertainties into final decisions.Entscheidung unter Unsicherheit im Modell-basierten Wassermanagement : Die Wissenschaft-Praxis Schnittstelle Eine zentrale Herausforderung für das Wassermanagement ist, den Ausgleich zwischen verschiedenen Wassernutzern und ihren Bedürfnissen herzustellen, bei gleichzeitiger Berücksichtigung zeitlicher und räumlicher Variabilität sowie Extreme des Wasserdargebots. Zunehmende Unsicherheiten aufgrund des Umweltwandels und sozialen Wandels erschweren das Management dieser Ressourcen zusätzlich. Die Integration von Unsicherheiten in Entscheidungsprozesse im Wassermanagement ist daher von besonderer Bedeutung, um auf unerwartete Ereignisse und eine große Bandbreite an möglichen Zukunftsszenarien vorbereitet zu sein. Ziel der Arbeit ist es zum Verständnis beizutragen, wie wissenschaftliche Unsicherheiten besser in Planungs- und Entscheidungsprozesse des modell-basierten Wassermanagements integriert werden und die Qualität des Wassermanagements damit verbessert werden kann. Hierbei wird die Hypothese verfolgt, dass das Verständnis und die Identifikation der Pluralität von Akteuren und ihrer unterschiedlichen Ansätze, Perspektiven und Entscheidungsmuster einen Schlüsselaspekt darstellen, um einen Beitrag zur Überbrückung der Lücke zwischen Forschung und Praxis zu leisten. Hauptmethoden, um die Ziele dieser Arbeit zu erreichen, sind umfangreiche Experteninterviews, Umfragen und qualitative Systemmodellierung. Dabei ist die intensive Auseinandersetzung mit Praxisakteurinnen und -akteuren ein zentrales Element, um die Wahrnehmung und den Umgang mit Unsicherheiten von Wasserressourcenmanagerinnen und -managern einschätzen zu können. Während die Ergebnisse hauptsächlich am Beispiel des Talsperrenmanagements unter sich ändernden intra-annuellen und annuellen Rahmenbedingungen erläutert werden, können sie auch auf alle anderen wasserbezogenen Bereiche übertragen werden. Die zentrale Erkenntnis dieser Arbeit besteht darin, dass Wassermanagerinnen und -manager Unsicherheiten einen hohen Wert beimessen. Die Wahrnehmung und Berücksichtigung von Unsicherheiten und Handlungskapazitäten variieren jedoch in Abhängigkeit von der Erfahrungsstufe der Praxisakteurinnen und -akteure, ihres Bildungshintergrunds, ihres Arbeitgebers, sowie ihrer Zugehörigkeit zu bestimmten Geschäftsbereichen. In Anlehnung an ihr berufliches Umfeld haben diese Akteurinnen und Akteure verschiedene Strategien zum Umgang mit Unsicherheiten entwickelt, die auf den ersten Blick nur schwer von Wissenschaftlerinnen und Wissenschaftlern wahrgenommen werden. Zusätzlich spielt Erfahrungswissen im Umgang mit wissenschaftlichen Unsicherheiten und Prozessunsicherheiten eine große Rolle. Fehlende Transparenz, Normen und Regularien in einem hoch politisierten Umfeld erschweren die Integration von Unsicherheiten. Im Rahmen der Arbeit wurden drei Werkzeuge zur Verbesserung der Transparenz und Integration von Unsicherheiten entwickelt: 1) eine 2x2 Unsicherheitsmatrix, 2) ein Integrations- und Analysekonzept, sowie 3) ein qualitatives Systemmodel. Insgesamt wurden Kriterien identifiziert, Voraussetzungen erläutert sowie eine praktische Strategie entwickelt, wie die Integration von wissenschaftlichen Unsicherheiten in wasserbezogene Planungs- und Entscheidungsprozesse verbessert werden kann. Es werden Ansätze aufgezeigt, mit denen die Nutzbarkeit von Unsicherheitsinformationen erhöht werden kann und die einen vertieften Diskurs zwischen Praxisakteurinnen und -akteuren untereinander sowie zwischen Wissenschaft und Praxis ermöglichen. Der theoretische Beitrag dieser Arbeit hebt die Bedeutung der Interrelationen von Unsicherheiten und der Pluralität an Perspektiven und Strategien hervor. Indem diese Vielfalt hervorgehoben wird, wird die Forschung an der Schnittstelle Wissenschaft-Praxis bereichert, da sie alte Annahmen linear-kausaler Zusammenhänge von Informationen verwirft und Raum für eine Pluralität an Wissen sowie unterschiedliche Herangehensweisen hinsichtlich Unsicherheitsintegration in finale Entscheidungen eröffnet

The ancient forests of La Gomera, Canary Islands, and their sensitivity to environmental change

Garajonay National Park in La Gomera (Canary Islands) contains one of the largest remnant areas of a forest formation once widespread throughout Europe and North Africa. Here, we aim to address the long-term dynamics (the last 9600 cal. years) of the monteverde forest (laurel forest and Morella-Erica heath) located close to the summit of the National Park (1487 m a.s.l.) and determine past environmental and human impacts. 2. We used palaeoecological (fossil pollen, microscopic and macroscopic charcoal) and multivariate ecological techniques to identify compositional change in the monteverde forest in relation to potential climatic and human influences, based on the analysis of a core site at 1250-m elevation. 3. The regional mid-Holocene change towards drier conditions was matched in this system by a fairly rapid shift in representation of key forest elements, with declines in Canarian palm tree (Phoenix canariensis), Canarian willow (Salix canariensis) and certain laurel forest taxa and an increase in representation of the Morella–Erica woody heath. 4. Charcoal data suggest that humans arrived on the island between about 3000 and 1800 years ago, a period of minimal vegetation change. Levels of burning over the last 800 years are among the lowest of the entire 9600 years. 5. Synthesis. A rapid climatic-induced shift of forest taxa occurred 5500 years ago, with a decrease in hygrophilous species in the pollen record. In contrast, we found no evidence of a significant response to human colonization. These findings support the idea that Garajonay National Park is protecting a truly ancient relict, comprising a largely natural rather than cultural legacy

Overview of habitat history in subtropical oceanic island summit ecosystems

Summit ecosystems of oceanic islands constitute one of the most ephemeral and isolated ecosystems existing, harboring specific features that confer on their biota an outstanding distinctness. Summits are short-lived entities, being the last ecosystems to be constructed during the growth of the new oceanic island, and the first to vanish due either to island subsidence, island erosion, or both. Whereas their geological emergence/disappearance is controlled by the volcanic/erosion activity, Pleistocene glaciations in the past million years, by forcing the altitudinal shift of the timberline, have also likely created or destroyed summit ecosystems, enabling the appearance of alpine ecosystems during glacial maxima where they were not present in interglacial periods and vice versa. On the other hand, summit ecosystems constitute islands within islands, being more isolated from climatically similar ecosystems than the coastlines of the islands containing them. Thus summit biota, frequently displaying a high endemicity, may originate either through dispersal from other close summit ecosystems during peak periods, or from the colonization of the summits and later evolution to the new conditions from mid-altitude species of the same island. Conversely, if peak periods are absent, the disappearance of summit ecosystems implies the extinction or extirpation of their constitutive species. Current summit species have likely occupied a much larger area during glacial periods. Thus the summits may be classified as climatic refuges. This is especially the case if glacial periods were associated with much drier conditions on oceanic islands as is the case on continents

Newly discovered seed dispersal system of Juniperus cedrus questions the pristine nature of the high elevation scrub of El Teide (Tenerife, Canary Islands)

As a working hypothesis, we examined evidence for the former presence of a climacic woodland of Juniperus cedrus above the pine forest in the high elevation area of Tenerife (Canary Islands), which would indicate that the current dominant vegetation (endemic Spartocytisus supranubius scrub) may not be pristine. The main causes of the great regression of this woodland were caused by human activities (timber harvesting, herbivory by goats, and fires). The main support for this hypothesis is the survival of a presumably relict seed dispersal system of the endangered endemic J. cedrus, which relies mainly on the wintering thrush Turdus torquatus. The fact that genetic factors are directly involved in the control of bird migration routes strongly supports the idea that this interaction could be remnant of an older system, probably more widespread in the past. To test this hypothesis, we propose that a paleoecological approach could reconstruct the vegetation dynamics in the Teide National Park (Tenerife) and the past presence of this seed disperser migratory thrush. The analysis of plant microfossils in sediments (e.g., pollen, spores, phytoliths, coprolites, and charcoal) would allow us to evaluate whether the current vegetation is the same as that which naturally existed in the past, and assess the impact of the anthropogenic and natural factors to which it has been subjected during history. The results of these analyses will be useful for future management policies and practices aimed at restoring the pristine landscape and biotic interactions of the Teide National Park. To our knowledge, the case presented in this contribution, based on the high dependence of the seed dispersal of an endemic tree (J. cedrus) on a migratory bird, is the only reported in the context of oceanic islands.Ministerio de Ciencia e InnovaciónGobierno de las Islas CanariasOrganismo Autónomo de Parques Nacionale

Ein außergewöhnliches "periglaziales" Frostbodenvorkommen bei Bonn : mit 2 Tabellen im Text und 21 Tafel : aus den Geographischen Instituten der Universität Bonn

Peter Höllerman

Die rezenten Gletscher der Pyrenäen

No abstract available

Integration of uncertainties in water and flood risk management

Water management is challenged by hydrological and socio-economic change and hence often forced to make costly and enduring decisions under uncertainty. Thus, thinking beyond current acknowledged and known limits is important to consider these changes and the dynamic of socio-hydrological interactions. For example, reservoir management aiming at flood reduction and mitigation has to cope with many different aspects of uncertainty. The question is to what extent can, do and should these uncertainties have implications on planning and decision-making? If practice recognises uncertainties they frequently use risk based decision approaches to acknowledge and handle them by e.g. relating them to other decision relevant factors, while science is mostly preoccupied in reducing these uncertainties. Both views are of relevance and a risk focused approach is needed to bridge the different perspectives covering all significant aspects of uncertainty. Based on a review of various characteristics and perceptions of uncertainty, this paper proposes a new analytical framework where the various aspects of uncertainty are condensed and a risk perspective is added. It thus goes beyond a pure typology and provides an overview of neuralgic points and their location and appearance during the decision-making process. Moreover this paper supports a structured and evaluated knowledge assessment and knowledge transfer for informed decision-making and points out potential fields of action and uncertainty reduction. Reservoir management targeting at flood prevention is used as an illustration to present the analytical framework, which is also amended by the needs and demands of practitioners, using first results of expert interviews