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The topography of first-order catchments in a region of western Amazonia was found to exhibit distinctive, recurrent features: a steep, straight lower side slope, a flat or nearly flat terrace at an intermediate elevation between valley floor and interfluve, and an upper side slope connecting interfluve and intermediate terrace. A detailed survey of soil-saturated hydraulic conductivity (K sat)-depth relationships, involving 740 undisturbed soil cores, was conducted in a 0.75-ha first-order catchment. The sampling approach was stratified with respect to the above slope units. Exploratory data analysis suggested fourth-root transformation of batches from the 0–0.1 m depth interval, log transformation of batches from the subsequent 0.1 m depth increments, and the use of robust estimators of location and scale. The K sat of the steep lower side slope decreased from 46 to 0.1 mm/h over the overall sampling depth of 0.4 m. The corresponding decrease was from 46 to 0.1 mm/h on the intermediate terrace, from 335 to 0.01 mm/h on the upper side slope, and from 550 to 0.015 mm/h on the interfluve. A depthwise comparison of these slope units led to the formulation of several hypotheses concerning the link between K sat and topography.
Rainfall erosivities as defined by the R factor from the universal soil loss equation were determined for all events during a two-year period at the station La Cuenca in western Amazonia. Three methods based on a power relationship between rainfall amount and erosivity were then applied to estimate event and daily rainfall erosivities from the respective rainfall amounts. A test of the resulting regression equations against an independent data set proved all three methods equally adequate in predicting rainfall erosivity from daily rainfall amount. We recommend the Richardson model for testing in the Amazon Basin, and its use with the coefficient from La Cuenca in western Amazonia.
Throughfall measurements were made under primary terra firme rainforest in the Rio Pichis valley, in the Upper Amazon Basin of Peru. Based on 214 precipitation events over nearly 18 months, throughfall was estimated to be 83.1±8.8% of gross precipitation. Regression analysis of all events revealed that gross precipitation is the only significant explanatory variable; the use of one-burst events does not significantly improve the regression relationship. Gross precipitation is, however, a poor predictor of throughfall for small rainfall events. The two forest structure parameters, canopy capacity, S, and free throughfall coefficient, p, were determined to be 1.3±0.2 mm and 0.32±0.18 mm. Rainfall intensity was found to influence these parameters. New methods which attempt to minimize the influence of meteorologic variables are used to estimate the potential values of these canopy parameters.
Fast analysis of different species of molecules in soils is investigated by capillary electrophoresis (CE). Several CE techniques for the analysis of inorganic ions and carbohydrates have been tested. With regard to the intents of pedologists and the usually large number of soil analyses a bundle of CE systems is proposed, capable of effecting time-saving soil analyses. Adapted electrolyte systems recently published and new separation systems are described. Examples of the application of these methods to two different soil samples are presented.
Chemical fingerprints of hydrological compartments and flow paths at La Cuenca, western Amazonia
(1995)
A forested first-order catchment in western Amazonia was monitored for 2 years to determine the chemical fingerprints of precipitation, throughfall, overland flow, pipe flow, soil water, groundwater, and streamflow. We used five tracers (hydrogen, calcium, magnesium, potassium, and silica) to distinguish “fast” flow paths mainly influenced by the biological subsystem from “slow” flow paths in the geochemical subsystem. The former comprise throughfall, overland flow, and pipe flow and are characterized by a high potassium/silica ratio; the latter are represented by soil water and groundwater, which have a low potassium/silica ratio. Soil water and groundwater differ with respect to calcium and magnesium. The groundwater-controlled streamflow chemistry is strongly modified by contributions from fast flow paths during precipitation events. The high potassium/silica ratio of these flow paths suggests that the storm flow response at La Cuenca is dominated by event water.
Previous hydrometric studies demonstrated the prevalence of overland flow as a hydrological pathway in the tropical rain forest catchment of South Creek, northeast Queensland. The purpose of this study was to consider this information in a mixing analysis with the aim of identifying sources of, and of estimating their contribution to, storm flow during two events in February 1993. K and acid-neutralizing capacity (ANC) were used as tracers because they provided the best separation of the potential sources, saturation overland flow, soil water from depths of 0.3, 0.6, and 1.2 m, and hillslope groundwater in a two-dimensional mixing plot. It was necessary to distinguish between saturation overland flow, generated at the soil surface and following unchanneled pathways, and overland flow in incised pathways. This latter type of overland flow was a mixture of saturation overland flow (event water) with high concentrations of K and a low ANC, soil water (preevent water) with low concentrations of K and a low ANC, and groundwater (preevent water) with low concentrations of K and a high ANC. The same sources explained the streamwater chemistry during the two events with strongly differing rainfall and antecedent moisture conditions. The contribution of saturation overland flow dominated the storm flow during the first, high-intensity, 178-mm event, while the contribution of soil water reached 50% during peak flow of the second, low-intensity, 44-mm event 5 days later. This latter result is remarkably similar to soil water contributions to storm flow in mountainous forested catchments of the southeastern United States. In terms of event and preevent water the storm flow hydrograph of the high-intensity event is dominated by event water and that of the low-intensity event by preevent water. This study highlights the problems of applying mixing analyses to overland flow-dominated catchments and soil environments with a poorly developed vertical chemical zonation and emphasizes the need for independent hydrometric information for a complete characterization of watershed hydrology and chemistry.
Geographie in der Postmoderne? : zur Kritik postmodernen Denkens in Stadtforschung und Geographie
(1996)
Ethologie und Umweltbildung
(1998)
Arbeitsgruppe Multimedia
(1999)
Arbeitsgruppe Internet
(1999)
Umweltbildung im Cyberspace
(1999)
Entwicklung und Gestaltung von Erholungsgebieten in Bergbaufolgelandschaften der Niederlausitz
(1999)
Predictability of hydrologic response at the plot and catchment scales: Role of initial conditions
(2004)
This paper examines the effect of uncertain initial soil moisture on hydrologic response at the plot scale (1 m2) and the catchment scale (3.6 km2) in the presence of threshold transitions between matrix and preferential flow. We adopt the concepts of microstates and macrostates from statistical mechanics. The microstates are the detailed patterns of initial soil moisture that are inherently unknown, while the macrostates are specified by the statistical distributions of initial soil moisture that can be derived from the measurements typically available in field experiments. We use a physically based model and ensure that it closely represents the processes in the Weiherbach catchment, Germany. We then use the model to generate hydrologic response to hypothetical irrigation events and rainfall events for multiple realizations of initial soil moisture microstates that are all consistent with the same macrostate. As the measures of uncertainty at the plot scale we use the coefficient of variation and the scaled range of simulated vertical bromide transport distances between realizations. At the catchment scale we use similar statistics derived from simulated flood peak discharges. The simulations indicate that at both scales the predictability depends on the average initial soil moisture state and is at a minimum around the soil moisture value where the transition from matrix to macropore flow occurs. The predictability increases with rainfall intensity. The predictability increases with scale with maximum absolute errors of 90 and 32% at the plot scale and the catchment scale, respectively. It is argued that even if we assume perfect knowledge on the processes, the level of detail with which one can measure the initial conditions along with the nonlinearity of the system will set limits to the repeatability of experiments and limits to the predictability of models at the plot and catchment scales.
A fine-grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the Vorarlberg Alps, Austria. For that purpose intensive hydrometeorological, hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998–2001. Subsurface water dynamics at the creeping slope turned out to be dominated by a three-dimensional pressure system. The pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south-western part of the hillslope. The related pressure signal was shown to propagate further downhill, causing fast reactions of the piezometric head at 5Ð5 m depth on a daily time scale. The observed pressure reactions might belong to a temporary hillslope water body that extends further downhill. The related buoyancy forces could be one of the driving forces for the mass movement. A physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production. It was possible to reproduce surface runoff and observed pressure reactions in principle. However, as soil hydraulic functions were only estimated on pedotransfer functions, a quantitative comparison between observed and simulated subsurface dynamics is not feasible. Nevertheless, the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model. Copyright 2005 John Wiley & Sons, Ltd. KEY WORDS rainfall-induced landslides; soil creep; hydrological modelling; Vorarlberg; Austria; pressure propagation
Voraussetzung für die nachhaltige Bewirtschaftung von Tieflandflusseinzugsgebieten ist ein umfassendes Verständnis der Wasserhaushalts- und Stofftransportprozesse in der Flussaue. Das Ziel dieser Arbeit ist die Untersuchung der Wasserhaushaltsprozesse und Stofftransportvorgänge innerhalb der grundwassergeprägten Talauenlandschaften von Tieflandeinzugsgebieten am Beispiel der im Nordostdeutschen Tiefland gelegenen Havel. Die Arbeiten in verschieden skaligen Teileinzugsgebieten der Havel beschäftigen sich dabei zum einen mit der experimentellen Untersuchung und vorrangig qualitativen Beschreibung der Wasserhaushaltsdynamik, zum anderen mit der Entwicklung eines zur quantitativen Analyse von Wasserhaushalts- und Stofftransportprozessen geeigneten Modells und der anschließenden Modellsimulation von Wasserhaushalt und Stickstoffmetabolik im Grundwasser sowie der Simulation von Landnutzungs- und Gewässerstrukturszenarien.
Evaluation in der Praxis: : Aktuelle Beispiele aus der Stadt-, Regional- und Umweltentwicklung
(2005)
Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Problemstellung • Geoökologische Prozessforschung versucht für große Landschaftsausschnitte, die in der Natur ablaufenden und vom Menschen beeinflussten Prozesse mit Hilfe von Modellen nachzuvollziehen • exakte Erfassung der Ausstattung des Untersuchungsraumes ist wesentliche Voraussetzung für eine wirklichkeitsnahe Abbildung • Modelle derzeit weder in der Lage, alle ablaufenden Prozesse in die Betrachtung einzubeziehen, noch präzise Eingangsdaten bei der Beschreibung des Ausgangszustandes zu verarbeiten • häufig liegen Modelleingangsdaten nicht in der notwendigen Präzision vor • In Modellen wird Ausstattung eines Untersuchungsgebietes über den Boden, den Grundwassereinfluss und die Flächennutzung beschrieben • Flächennutzung besitzt weitgehend statische Elemente (Nutzungstypen Wald, Gewässer, Siedlung) und hochdynamische Elemente (jährlicher Wechsel der Fruchtart auf jedem Acker) • Bedarf nach detaillierter (lage- und zeitkonkreter) Eingabe der Verteilung der Ackerfrüchte im Modellzeitraum, da Landwirtschaft als eine der bedeutenden Quellen für diffusen Nährstoffeintrag ins Ökosystem angesehen wird Stand der Forschung • bei Erfassung von Kulturen der Landwirtschaft aus Fernerkundungsdaten hat sich multitemporale Klassifizierung als sinnvoll erwiesen, weil sich anhand einer Einzelaufnahme die verschiedenen Kulturen nicht sicher trennen lassen • Klassifizierung erfolgt mit überwachten Methoden unter Verwendung von Trainingsflächen im Datensatz, von denen die dort angebaute Frucht bekannt ist • in die Klassifizierung werden zusätzliche Informationen einbezogen (Fuzzy), die Auskunft über die Wahrscheinlichkeit des Auftretens der Frucht geben (Anbaueignung in Abhängigkeit von Hangneigung, Niederschlag, Höhenlage, Boden) Die Ergebnisse dieser Klassifikationen sind meist nicht auf andere Landschaftsausschnitte und Anbaujahre übertragbar, weil die Ausprägung der Spektralsignatur einer Kultur durch veränderte Boden- und Witterungsbedingungen variiert. Lösungsansatz • auf Basis von Satellitendaten und Anbauinformationen aus 15 aufeinander folgenden Jahren (35 Aufnahmetermine) sollten von Witterung und Boden unabhängige Jahreskurven der spektralen Charakteristik wichtiger Ackerkulturen gewonnen werden, die den Wachstumsverlauf der Pflanzen beschreiben • diese Kurven sollen anstelle von Trainingsgebieten zur multitemporalen Klassifizierung von Daten eines Anbaujahres herangezogen werden Schlussfolgerungen und Ausblick • Prinzipiell erscheint Vorgehen erfolgreich, jedoch in Abhängigkeit von der Brauchbarkeit der herangezogenen Szenen schwankt Güte des Ergebnisses noch • Verfahren stellt wesentlichen Fortschritt zu bisherigem Vorgehen auf Trainingsflächenbasis dar • ist zumindest im Untersuchungsgebiet immer wieder ohne weitere Kenntnis von Anbauinformationen anwendbar, lediglich exakte phänologische Datierung der dann verwendeten Aufnahmen erforderlich • für andere Gebiete (Variation in Niederschlag und Boden) ist Anpassung der phänologischen Datierung der Kurven erforderlich (Form ist weiter verwendbar) • optimale Bildkombination zur Trennung aller Kulturen ist: Anfang/Mitte April – Mitte Mai – Anfang Juli – Mitte August – Mitte September • Kombination sollte bei verbesserter Verfügbarkeit von Daten beschaffbar sein • problematisch scheinen Trockensituationen im Mai und Juni zu sein, so dass zu schnell reifende Wintergetreide nicht richtig erkannt werden, Bedarf Bodeninformationen einzubeziehen • Trennung von Hackfrüchten weiterhin problematisch (wie schon in bisherigen Verfahren), führt zu übermäßigen Anteilen im Ergebnis, in Abhängigkeit vom Anbauanteil besser vernachlässigen • Einbeziehung von Fuzzyinformationen erscheint sinnvoll • Zusammenhang von Bodengüte und Frucht (Anbaueignung eines Bodens für eine Frucht) • Wasserverfügbarkeit am Standort (in Abhängigkeit von Speichervermögen des Bodens, Grundwasseranschluss und Niederschlag) • Summe der Niederschläge bis zum Aufnahmezeitpunkt (Trockenheitsindex) <hr> Dokument 1: Foliensatz | Dokument 2: Abstract <hr> Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Entwicklung, Implementierung und Erprobung eines planetaren Informationssystems auf Basis von ArcGIS
(2007)
Mit der Entwicklung der modernen Raumfahrt Mitte der 60er-Jahre des zwanzigsten Jahrhunderts und der Eroberung des Weltraums brach eine neue Epoche der bis dato auf Beobachtungen mit dem Teleskop gestützten planetaren Forschung an. Während des Wettrennens um die technologische Führerschaft im All zur Zeit des Kalten Krieges war das erste Ziel die Entsendung von Satelliten zur Erdbeobachtung, denen aber schon bald Sonden zum Mond und den benachbarten Planeten folgten. Diese Missionen lieferten eine enorme Fülle von Informationen in Form von Bildern und Messergebnissen in unterschiedlichen Datenformaten. Diese galt und gilt es zu strukturieren, zu verwalten, zu aktualisieren und zu interpretieren. Für die Interpretation terrestrischer Daten werden geographische Informationssysteme (GIS) hinzugezogen, die jedoch für planetare Anwendungen aufgrund unterschiedlicher Voraussetzungen nicht ohne weiteres eingesetzt werden können. Daher wurde im Rahmen dieser Arbeit die für die Verwaltung von geographischen Daten der Erdfernerkundung kommerziell erhältliche Software ArcGIS Desktop 9.0 / 9.1 (ESRI) mit eigenen Programmen und Modulen für die Planetenforschung angepasst. Diese ermöglichen die Aufbereitung und den Import planetarer Bild- und Textinformation in die kommerzielle Software. Zusätzlich wurde eine planetare Datenbank zur Speicherung und zentralen Verwaltung der Informationen aufgebaut. Die im Rahmen dieser Arbeit entwickelten Softwarekomponenten ermöglichen die schnelle und benutzerfreundliche Aufbereitung der in der Datenbank gehaltenen Informationen und das Auslesen in Dateiformate, die für geographische Informationssysteme geeignet sind. Des Weiteren wurde eine „Werkzeugleiste“ für ArcGIS entwickelt, die das Arbeiten mit planetaren Datensätzen beträchtlich beschleunigt und vereinfacht. Sie beinhaltet auch Module zur wissenschaftlichen Interpretation der planetaren Informationen, wie beispielsweise der Berechnung der Oberflächenrauigkeit der Marsoberfläche inklusive der flächendeckenden Kalibrierung der Eingangs-Basisdaten. Exemplarisch konnte gezeigt werden, dass das Verfahren eine verbesserte Berechnung der Oberflächenrauigkeit ermöglicht, als bisher angewandte Ansätze. Zudem wurde eine auf ArcGIS basierende Prozesskette zur Berechnung von hierarchischen Flussnetzen entwickelt und erprobt. Das terrestrische Beispiel, die Analyse eines Abflusssystems auf Island, zeigte eine sehr große Übereinstimmung der errechneten Gewässernetze mit den morphologischen Gegebenheiten vor Ort. Daraus ließ sich eine hohe Genauigkeit der mit demselben Ansatz errechneten Gewässernetze auf dem Mars ableiten. Auf der Grundlage der in dieser Arbeit entwickelten Programme und Module lassen sich auch Daten zukünftiger Missionen aufbereiten und in ein solches System einbinden, um diese mit eigenen Ansätzen zu verwalten, zu aktualisieren und für neue wissenschaftliche Fragestellungen perfekt anzupassen, einzusetzen und zu präsentieren, um so neue wissenschaftliche Erkenntnisse in der Planetenforschung zu gewinnen.
Ziel dieser Arbeit war es, die Stickstoff- und Phosphorprozesse im nordostdeutschen Tiefland detailliert zu untersuchen und Handlungsoptionen hinsichtlich der Landnutzung zur nachhaltigen Steuerung der Stickstoff- und Phosphoreinträge in die Fließgewässer aufzuzeigen. Als Grundvoraussetzung für die Modellierung des Nährstoffhaushaltes mussten zunächst die hydrologischen Prozesse und die Abflüsse für die Einzugsgebiete validiert werden. Dafür wurde in dieser Arbeit das ökohydrologische Modell SWIM verwendet. Die Abflussmodellierung umfasste den Zeitraum 1991 - 2000. Die Ergebnisse dazu zeigen, dass SWIM in der Lage war, die hydrologischen Prozesse in den Untersuchungsgebieten adäquat wiederzugeben. Auf der Grundlage der Modellierung des Wasserhaushaltes wurden mit SWIM die Stoffumsatzprozesse für den Zeitraum 1996 - 2000 simuliert. Um dabei besonders das Prozessgeschehen im Tiefland zu berücksichtigen, war die Erweiterung von SWIM um einen Ammonium-Pool mit dessen Umsatzprozessen erforderlich. Außerdem wurde der Prozess der Nährstoffversickerung so ergänzt, dass neben Nitrat auch Ammonium und Phosphat durch das gesamte Bodenprofil verlagert und über die Abflusskomponenten zum Gebietsauslass transportiert werden können. Mit diesen Modellerweiterungen konnten die Stickstoff und Phosphorprozesse in den Untersuchungsgebieten gut abgebildet werden. Mit dem so validierten Modell wurden weitere Anwendungen ermöglicht. Nährstoffsimulationen für den Zeitraum 1981 bis 2000 dienten der Untersuchung des abnehmenden Trends in den Nährstoffkonzentrationen der Nuthe. Die Untersuchungsergebnisse lassen deutlich erkennen, dass sich die Konzentrationen nach 1990 hauptsächlich auf Grund der Reduzierung der Einträge aus punktförmigen Quellen und Rieselfeldern verringert haben. Weitere Modellrechnungen zur Herkunft der Nährstoffe haben ergeben, dass Nitrat überwiegend aus diffusen Quellen, Ammonium und Phosphat dagegen aus punktförmigen Quellen stammen. Als besonders sensitiv auf die Modellergebnisse haben sich die Parameter zu Landnutzung und -management und die Durchwurzelungstiefe der Pflanzen herausgestellt. Abschließend wurden verschiedene Landnutzungsszenarien angewendet. Die Ergebnisse zu den Szenariorechnungen zeigen, dass fast alle vorgegebenen Landnutzungsszenarien zu einer Verringerung der Stickstoff- bzw. Phosphoremissionen führten. Die Anwendung von Szenarien, die alle relevanten Zielvorgaben und Empfehlungen zum Ressourcenschutz berücksichtigen, zeigen die größten Veränderungen.
Forests are a key resource serving a multitude of functions such as providing income to forest owners, supplying industries with timber, protecting water resources, and maintaining biodiversity. Recently much attention has been given to the role of forests in the global carbon cycle and their management for increased carbon sequestration as a possible mitigation option against climate change. Furthermore, the use of harvested wood can contribute to the reduction of atmospheric carbon through (i) carbon sequestration in wood products, (ii) the substitution of non-wood products with wood products, and (iii) through the use of wood as a biofuel to replace fossil fuels. Forest resource managers are challenged by the task to balance these multiple while simultaneously meeting economic requirements and taking into consideration the demands of stakeholder groups. Additionally, risks and uncertainties with regard to uncontrollable external variables such as climate have to be considered in the decision making process. In this study a scientific stakeholder dialogue with forest-related stakeholder groups in the Federal State of Brandenburg was accomplished. The main results of this dialogue were the definition of major forest functions (carbon sequestration, groundwater recharge, biodiversity, and timber production) and priority setting among them by the stakeholders using the pair-wise comparison technique. The impact of different forest management strategies and climate change scenarios on the main functions of forest ecosystems were evaluated at the Kleinsee management unit in south-east Brandenburg. Forest management strategies were simulated over 100 years using the forest growth model 4C and a wood product model (WPM). A current climate scenario and two climate change scenarios based on global circulation models (GCMs) HadCM2 and ECHAM4 were applied. The climate change scenario positively influenced stand productivity, carbon sequestration, and income. The impact on the other forest functions was small. Furthermore, the overall utility of forest management strategies were compared under the priority settings of stakeholders by a multi-criteria analysis (MCA) method. Significant differences in priority setting and the choice of an adequate management strategy were found for the environmentalists on one side and the more economy-oriented forest managers of public and private owned forests on the other side. From an ecological perspective, a conservation strategy would be preferable under all climate scenarios, but the business as usual management would also fit the expectations under the current climate. In contrast, a forest manager in public-owned forests or a private forest owner would prefer a management strategy with an intermediate thinning intensity and a high share of pine stands to enhance income from timber production while maintaining the other forest functions. The analysis served as an example for the combined application of simulation tools and a MCA method for the evaluation of management strategies under multi-purpose and multi-user settings with changing climatic conditions. Another focus was set on quantifying the overall effect of forest management on carbon sequestration in the forest sector and the wood industry sector plus substitution effects. To achieve this objective, the carbon emission reduction potential of material and energy substitution (Smat and Sen) was estimated based on a literature review. On average, for each tonne of dry wood used in a wood product substituting a non-wood product, 0.71 fewer tonnes of fossil carbon are emitted into to the atmosphere. Based on Smat and Sen, the calculation of the carbon emission reduction through substitution was implemented in the WPM. Carbon sequestration and substitution effects of management strategies were simulated at three local scales using the WPM and the forest growth models 4C (management unit level) or EFISCEN (federal state of Brandenburg and Germany). An investigation was conducted on the influence of uncertainties in the initialisation of the WPM, Smat, and basic conditions of the wood product sector on carbon sequestration. Results showed that carbon sequestration in the wood industry sector plus substitution effects exceeded sequestration in the forest sector. In contrast to the carbon pools in the forest sector, which acted as sink or source, the substitution effects continually reduced carbon emission as long as forests are managed and timber is harvested. The main climate protection function was investigated for energy substitution which accounted for about half of the total carbon sequestration, followed by carbon storage in landfills. In Germany, the absolute annual carbon sequestration in the forest and wood industry sector plus substitution effects was 19.9 Mt C. Over 50 years the wood industry sector contributed 70% of the total carbon sequestration plus substitution effects.
This thesis aims to quantify the human impact on the natural resource water at the landscape scale. The drivers in the federal state of Brandenburg (Germany), the area under investigation, are land-use changes induced by policy decisions at European and federal state level. The water resources of the federal state are particularly sensitive to changes in land-use due to low precipitation rates in the summer combined with sandy soils and high evapotranspiration rates. Key elements in landscape hydrology are forests because of their unique capacity to transport water from the soil to the atmosphere. Given these circumstances, decisions made at any level of administration that may have effects on the forest sector in the state are critical in relation to the water cycle. It is therefore essential to evaluate any decision that may change forest area and structure in such a sensitive region. Thus, as a first step, it was necessary to develop and implement a model able to simulate possible interactions and feedbacks between forested surfaces and the hydrological cycle at the landscape scale. The result is a model for simulating the hydrological properties of forest stands based on a robust computation of the temporal and spatial LAI (leaf area index) dynamics. The approach allows the simulation of all relevant hydrological processes with a low parameter demand. It includes the interception of precipitation and transpiration of forest stands with and without groundwater in the rooting zone. The model also considers phenology, biomass allocation, as well as mortality and simple management practices. It has been implemented as a module in the eco-hydrological model SWIM (Soil and Water Integrated Model). This model has been tested in two pre-studies to verify the applicability of its hydrological process description for the hydrological conditions typical for the state. The newly implemented forest module has been tested for Scots Pine (Pinus sylvestris) and in parts for Common Oak (Quercus robur and Q. petraea) in Brandenburg. For Scots Pine the results demonstrate a good simulation of annual biomass increase and LAI in addition to the satisfactory simulation of litter production. A comparison of the simulated and measured data of the May sprout for Scots pine and leaf unfolding for Oak, as well as the evaluation against daily transpiration measurements for Scots Pine, does support the applicability of the approach. The interception of precipitation has also been simulated and compared with weekly observed data for a Scots Pine stand which displays satisfactory results in both the vegetation periods and annual sums. After the development and testing phase, the model is used to analyse the effects of two scenarios. The first scenario is an increase in forest area on abandoned agricultural land that is triggered by a decrease in European agricultural production support. The second one is a shift in species composition from predominant Scots Pine to Common Oak that is based on decisions of the regional forestry authority to support a more natural species composition. The scenario effects are modelled for the federal state of Brandenburg on a 50m grid utilising spatially explicit land-use patterns. The results, for the first scenario, suggest a negative impact of an increase in forest area (9.4% total state area) on the regional water balance, causing an increase in mean long-term annual evapotranspiration of 3.7% at 100% afforestation when compared to no afforestation. The relatively small annual change conceals a much more pronounced seasonal effect of a mean long-term evapotranspiration increase by 25.1% in the spring causing a pronounced reduction in groundwater recharge and runoff. The reduction causes a lag effect that aggravates the scarcity of water resources in the summer. In contrast, in the second scenario, a change in species composition in existing forests (29.2% total state area) from predominantly Scots Pine to Common Oak decreases the long-term annual mean evapotranspiration by 3.4%, accompanied by a much weaker, but apparent, seasonal pattern. Both scenarios exhibit a high spatial heterogeneity because of the distinct natural conditions in the different regions of the state. Areas with groundwater levels near the surface are particularly sensitive to changes in forest area and regions with relatively high proportion of forest respond strongly to the change in species composition. In both cases this regional response is masked by a smaller linear mean effect for the total state area. Two critical sources of uncertainty in the model results have been investigated. The first one originates from the model calibration parameters estimated in the pre-study for lowland regions, such as the federal state. The combined effect of the parameters, when changed within their physical meaningful limits, unveils an overestimation of the mean water balance by 1.6%. However, the distribution has a wide spread with 14.7% for the 90th percentile and -9.9% for the 10th percentile. The second source of uncertainty emerges from the parameterisation of the forest module. The analysis exhibits a standard deviation of 0.6 % over a ten year period in the mean of the simulated evapotranspiration as a result of variance in the key forest parameters. The analysis suggests that the combined uncertainty in the model results is dominated by the uncertainties of calibration parameters. Therefore, the effect of the first scenario might be underestimated because the calculated increase in evapotranspiration is too small. This may lead to an overestimation of the water balance towards runoff and groundwater recharge. The opposite can be assumed for the second scenario in which the decrease in evapotranspiration might be overestimated.
River reaches protected by dikes exhibit high damage potential due to strong value accumulation in the hinterland areas. While providing an efficient protection against low magnitude flood events, dikes may fail under the load of extreme water levels and long flood durations. Hazard and risk assessments for river reaches protected by dikes have not adequately considered the fluvial inundation processes up to now. Particularly, the processes of dike failures and their influence on the hinterland inundation and flood wave propagation lack comprehensive consideration. This study focuses on the development and application of a new modelling system which allows a comprehensive flood hazard assessment along diked river reaches under consideration of dike failures. The proposed Inundation Hazard Assessment Model (IHAM) represents a hybrid probabilistic-deterministic model. It comprises three models interactively coupled at runtime. These are: (1) 1D unsteady hydrodynamic model of river channel and floodplain flow between dikes, (2) probabilistic dike breach model which determines possible dike breach locations, breach widths and breach outflow discharges, and (3) 2D raster-based diffusion wave storage cell model of the hinterland areas behind the dikes. Due to the unsteady nature of the 1D and 2D coupled models, the dependence between hydraulic load at various locations along the reach is explicitly considered. The probabilistic dike breach model describes dike failures due to three failure mechanisms: overtopping, piping and slope instability caused by the seepage flow through the dike core (micro-instability). The 2D storage cell model driven by the breach outflow boundary conditions computes an extended spectrum of flood intensity indicators such as water depth, flow velocity, impulse, inundation duration and rate of water rise. IHAM is embedded in a Monte Carlo simulation in order to account for the natural variability of the flood generation processes reflected in the form of input hydrographs and for the randomness of dike failures given by breach locations, times and widths. The model was developed and tested on a ca. 91 km heavily diked river reach on the German part of the Elbe River between gauges Torgau and Vockerode. The reach is characterised by low slope and fairly flat extended hinterland areas. The scenario calculations for the developed synthetic input hydrographs for the main river and tributary were carried out for floods with return periods of T = 100, 200, 500, 1000 a. Based on the modelling results, probabilistic dike hazard maps could be generated that indicate the failure probability of each discretised dike section for every scenario magnitude. In the disaggregated display mode, the dike hazard maps indicate the failure probabilities for each considered breach mechanism. Besides the binary inundation patterns that indicate the probability of raster cells being inundated, IHAM generates probabilistic flood hazard maps. These maps display spatial patterns of the considered flood intensity indicators and their associated return periods. Finally, scenarios of polder deployment for the extreme floods with T = 200, 500, 1000 were simulated with IHAM. The developed IHAM simulation system represents a new scientific tool for studying fluvial inundation dynamics under extreme conditions incorporating effects of technical flood protection measures. With its major outputs in form of novel probabilistic inundation and dike hazard maps, the IHAM system has a high practical value for decision support in flood management.