1,721,084 research outputs found
The effect of bed porosity on turbulent flow in gravel-bed rivers
No full textThis thesis presents the main findings from laboratory experiments that were specially designed to study the effect of gravel bed porosity on the surface flow characteristics. The thesis also contains five primary and two secondary research papers in which the results are discussed in detail.
In order to study the effect of porosity on flow resistance and near-bed turbulence, a non-porous counterpart of a water-worked gravel-bed surface was produced using a casting technique. The casting technique was also used to study the influence of gravel grain orientation on bulk flow resistance. The accuracy of the casting technique was evaluated, and the results indicated that the cast replicated the original surface accurately. The vertical distribution of porosity in the water-worked gravel-bed was also investigated. Hydraulic measurements were performed over three different bed types: water-worked gravel-bed, cast-bed and rotated cast-bed (cast tiles were rotated 180 degrees). The rotated cast-bed imposed larger flow resistance on the flow, thus the grain orientation played an important role determining the flow resistance. Moreover, differences in flow resistance and turbulence characteristics between porous water-worked gravel-bed and non-porous cast-bed are discussed. The porous water-worked gravel-bed imposed slightly larger resistance on the flow than the non-porous cast-bed. The analysis of turbulence flow characteristics between water-worked gravel-bed and cast-bed revealed that a higher momentum flux occurred over the water-worked gravel-bed. Moreover, the form-induced stresses were higher over the cast-bed than over the gravel-bed. This was associated with a strong recirculation of the fluid over the cast-bed as fluid cannot infiltrate. In contrast, fluid can infiltrate into the subsurface of the water-worked gravel-bed, causing less recirculation in the water-sediment interface
Riprap design on the downstream slopes of rockfill dams
No full textSammendrag:
Erosjonssikring av stein er mye brukt, blant annet for å sikre nedstrøms skråning på steinfyllingsdammer mot erosjon fra ulykkeslaster som overtopping eller gjennomstrømning. Denne avhandlingen fokuserer på stabiliteten og utformingen av erosjonssikring av stein lagt som rauset steinsikring eller plastring. Plastring ble bygd ved å sette stein i forband med god innbyrdes kontakt og med lengste akse hellende mot skråningen. Forsøkene ble utført på en skråning på 1:1,5 (vertikalt: horisontalt). Plastringsparametere, bruddmekanismer, hydrauliske parametere og eksisterende stabilitetsanalyser ble undersøkt for å optimalisere utforming av rauset steinsikring og plastring på bratte skråninger. Stabiliteten til erosionssikringen ble undersøkt med fysiske modellforsøk i ulike målestokk og uttrykt gjennom det kritiske steinbaserte Froudetallet.
For å kvantifisere kreftene som virker på en spesifisk stein, ble det nylig utviklete måleutstyret ’Smartstone’ testet. En Smartstone sonde ble montert i en plastringsstein for å måle akselerasjonen i øyeblikket når steinen ble erodert fra plastringen. Den aktuelle versjonen av Smartstone må imiderltid bli videre utviklet for å tillate den ønskede anvendelsen.
Fysiske modellforsøk og feltforsøk med storskala plastringsstein ble utført for å undersøke stabiliteten til rauset steinsikring og plastring. Felt- og modellforsøkene med rauset steinsikring viste god overensstemmelse i forhold til stabilitet, pakningstetthet og det visuelt observerte strømningsmønsteret. Forsøkene utført med plastring hadde bra overensstemmelse mellom felt og modell i forhold til strømningsmønster og overtoppingshøyde. Plastringene i modellforsøkene var imidlertid tettere pakket og mer stabile enn i felt. Forskyvinger i plastringslaget ble målt i modellforsøkene. Forskyvingene førte til en glipe i overgangen mellom den horisontale kronen og skråningen. Plastringen ble ustabil når glipen hadde blitt større enn omtrent en steinlengde. Akkumulerende forskyvinger ble dermed identifisert som bruddmekanisme for plastring på bratte skråninger. Siden forskyvingene utviklet seg gradvis, anbefales det å inkludere tidsdimensjonen i stabilitetsanalyser i tillegg til vannføring. Plastring hadde i gjennomsnitt sju ganger større kritisk steinrelatert Froudetall enn rauset steinsikring. Imidlertid kan rauset steinsikring være stabil nok for noen bruksområder, og plastring bør bare bli vurdert hvis økt stabilitet er nødvendig. For å oppnå optimal utforming av erosjonssikring av stein, må kravene til type erosjonssikring, steinstørrelse og plastringstetthet, samt de tilhørende konstnadene, avveises mot det ønskete stabilitetsnivået.Zusammenfassung:
Deckwerke aus Steinen sind eine weitverbreitete Massnahme gegen Erosion. Sie werden unter anderem auf den luftseitigen Hängen von Staudämmen erstellt, um diese in ausserordentlichen Lastfällen wie Über- oder Durchströmen vor Erosion zu schützen. Die vorliegende Dissertation fokussiert auf die Stabilität solcher Deckwerke, die entweder als Blockwurf oder Blocksatz ausgeführt werden. Bei einem Blockwurf werden die Steine willkürlich verteilt. Ein Blocksatz hingegen besteht aus Steinen, die ineinandergreifend gesetzt werden. Die Steine können zusätzlich mit ihrer längsten Achse gegen den Hang geneigt platziert werden. Für die Versuche hatten die Hänge ein Gefälle von 1:1.5 (horizontal: vertikal). Die Parameter von Deckwerken aus Steinen, Fehlermechanismen, hydraulische Parameter und bestehenden Stabilitätsanalysen wurden untersucht, um die Bauweise der Deckwerke zu optimieren. Die Deckwerksstabilität wurde mit Modellversuchen in verschiedenen Massstäben ermittelt und durch die kritische steinbezogene Froude-Zahl ausgedrückt.
Um die Kräfte, die auf einen spezifischen Stein wirken, zu messen, wurde das neulich entwickelt ’Smartstone’ Messgerät getestet. Eine Smartstonesonde wurde in einen Stein eingebaut werden, um die Beschleunigung zu messen, wenn der Stein aus dem Deckwerk erodiert wird. Die aktuelle Version der Smartstones muss jedoch weiterentwickelt werden, um die gewünschte Anwendung zuzulassen.
Physische Modellversuche und Feldversuche mit grossmassstäblichen Steinen wurden durchgeführt, um die Deckwerksstabilität zu untersuchen. Die Stabilität, Setzungsdichte und die visuell beobachteten Strömungsverhältnisse stimmten für Blockwurf zwischen den Feld- und Modellversuchen überein. Die Strömungsverhältnisse und die Überströmungswassertiefe waren für Blocksatz in den Feld- und Modellversuchen ähnlich. Die Blocksätze im Modell waren jedoch dichter gesetzt und stabiler. In den Modellversuchen wurden die Verschiebungen von ausgewählten Steinen im Deckwerk gemessen. Die Verschiebungen führten zu einer Lücke im Übergang von der Dammkrone zum luftseitigen Hang. Der Blocksatz wurde unstabil, als die Lücke die Grösse einer Steinlänge überstieg. Folglich wurden Verschiebungen als Fehlermechanismus für Blocksätze auf steilen Hängen identifiziert. Da die Verschiebungen sukzessive anwuchsen, sollte die zeitliche Dimension in Stabilitätsuntersuchungen zusätzlich zum Abfluss berücksichtigt werden. Die kritische steinbezogene Froude-Zahl war für Blocksatz im Durchschnitt siebenmal höher als die von Blockwurf. Jedoch kann die Stabilität von Blockwurf für gewisse Anwendungen ausreichen und Blocksatz sollte nur in Betracht gezogen werden, falls eine erhöhte Stabilität erforderlich ist. Um die Bauweise von Steindeckwerken zu optimieren, müssen die Anforderungen wie Art des Deckwerks, Steingrösse und Setzungsdichte im Deckwerk sowohl als auch die damit verbundenen Kosten bezüglich dem gewünschten Stabilitätsniveau abgewogen werden. Froude-Zahl war für Blocksatz im Durchschnitt siebenmal höher als die von Blockwurf. Jedoch kann die Stabilität von Blockwurf für gewisse Anwendungen ausreichen und Blocksatz sollte nur in Betracht gezogen werden, falls eine erhöhte Stabilität erforderlich ist. Um die Bauweise von Steindeckwerken zu optimieren, müssen die Anforderungen wie Art des Deckwerks, Steingrösse und Setzungsdichte im Deckwerk sowohl als auch die damit verbundenen Kosten bezüglich dem gewünschten Stabilitätsniveau abgewogen werden.Abstract:
Riprap is widely used as erosion protection. To prevent erosion in case of accidental overtopping or trough flow, the downstream slopes of rockfill dams can be secured with riprap. The present thesis focuses on the stability and design of dumped and placed riprap made of natural stone. Placed riprap for the tests was constructed by setting stones in an interlocking pattern, with their longest axes inclined towards a slope of 1:1.5 (vertical: horizontal). Riprap parameters, failure mechanisms, hydraulic parameters and existing stability approaches were addressed to optimize riprap design on steep slopes. Riprap stability was investigated with physical model tests in different scales and was expressed through the critical stone-related Froude number.
In order to quantify the forces acting on a specific stone, the novel ’Smartstone’ monitoring equipment was tested. A Smartstone probe was mounted in a riprap stone to measure the acceleration in the moment when the stone was eroded from the riprap. However, the current version of the Smartstone equipment needs further development to allow for the desired application.
Physical model tests and field tests with large-scale riprap stones were carried out to investigate riprap stability. For dumped riprap, similarity was found between the field and model tests in terms of riprap stability, packing density and visually observed flow pattern. The model tests and field tests with placed riprap showed good agreement with regard to flow pattern and overtopping height. However, the placed ripraps in the model had a higher packing density and were more stable. Displacements within the riprap layer were monitored during the model tests. The displacements lead to a gap at the transition between the horizontal crest and the downstream slope. The riprap became unstable when the gap exceeded approximately one stone length. Accumulating displacements were hence identified as failure mechanism for placed riprap on steep slopes. Due to the gradual development of the displacements, the dimension of time is recommended to be included in stability analyses in addition to discharge. Placed riprap had on average a seven times higher critical stone-related Froude number than dumped riprap. However, dumped riprap might provide sufficient stability for certain applications, and placed riprap should just be considered if increased stability is required. For an optimized riprap design, the requirements about riprap type, stone size and packing density as well as the corresponding costs have to be balanced with the desired level of stability
Parametrisation of aquatic vegetation in hydraulic and coastal research: The importance of plant biomechanics in the hydrodynamics of vegetated flows
Full text linkUnderstanding the complexity of the interactions between aquatic biological systems and their physical environment is a critical condition for the sustainable management of aquatic environments. In such ecosystems, aquatic vegetation holds a central place by influencing flow and turbulent processes, thus playing a major role both from an engineering and ecological point of view. However, the characterisation of the hydrodynamics of vegetated flows is facing several issues due to the complexity of the plant-flow interactions. In such a complex system, the plant's biomechanical properties are a key parameter governing the interplay between the living organism and its physical environment: a variation of the plant’s mechanics in time or space will generally imply changes in these regulation processes, which in turn can lead to major changes in the physical/ecological environment. The consideration of mechanical interactions, however, is fairly new to engineers, biologists and ecologists, as it defines an interface between engineering and ecology. As a consequence, this area of research has remained mostly unexplored and a lot of processes are to be discovered at the edge of the different disciplines.
This thesis deepened the level of the understanding of plant-flow mechanical interactions and of the plant structural properties, in order to improve the parametrisation of aquatic vegetation in hydraulic and coastal research. Measurement techniques and experimental protocols were developed to collect plant biomechanical properties and a methodology for the collection of such data was provided based on the flexibility of the plant elements. New methods to design plant surrogates for hydraulic experimentation were further investigated based on mechanical similarity. In parallel, this thesis reviewed the measurement techniques commonly used to measure drag forces on submerged plants, and developed a theoretical framework to estimate random wave and random wave-plus-current induced drag forces on submerged plants. This framework is based on the definition of a drag coefficient for a given type of plant. Moreover, the common drag coefficient formulations were discussed, identifying possibilities for a standardisation of the formulations for oscillatory and steady flows. Finally, in order to understand the effects of the development of a biological community at an interface fluid/solid, the example of marine biofouling was investigated through flow visualisation. The methodologies developed in this thesis are to be used in ongoing projects and will trigger new research activities at NTNU and elsewhere
Ecosystem restoration at Fundu Mare Island in the Inner Danube Delta near Braila (Romania) - Hydrodynamic optimisation
No full textWithin the last century, the extensive implementation of engineering measures in European rivers has caused significant changes in river hydrology, water quality and local ecology, inducing major impact on the environment of wetlands. As a result, degradation of habitat quality in combination with loss of biodiversity are the major consequences. Along the Romanian Danube River, large parts of former wetlands, lakes and braided river reaches have disappeared, with the wetland Fundu Mare Island representing one of its last remains. In recent years, a reduction of the water levels and willow encroachment into the aquatic zone were observed, affecting the high biological diversity of the island. In order to protect biodiversity, the implementation of restoration measures in Fundu Mare Island is investigated within the project Restoration of the aquatic and terrestrial ecosystems complex, from Fundu Mare Island, part of the Small Wetland of Brăila funded by EEA-grants. As part of the project, this work aims at the investigation of a number of restoration scenarios that allow conservation of biodiversity. The implementation of a two-dimensional numerical model was examined in Delft3D. Due to the time restrictions of the thesis and unforeseen problems during model calibration, a general investigation by the application of a simplified water balance approach was applied. Based on the results, it can be concluded that the water levels on the island can be positively influenced by the implementation of weirs. In order to meet the requirements regarding security, hydrological uncertainty, and ecological demands, the installation of the bag weir is recommended. The demands of fish in the area can be met by seasonal opening of the channels on the island to enhance water exchange and provide connectivity between Fundu Mare Island and the Danube. However, further research needs to be carried out to analyse the feasibility of the implementation with regard to the simplifications made in this approach
Ecosystem restoration at Fundu Mare Island in the Inner Danube Delta near Braila (Romania) - Hydrodynamic optimisation
Full text linkWithin the last century, the extensive implementation of engineering measures in European rivers has caused significant changes in river hydrology, water quality and local ecology, inducing major impact on the environment of wetlands. As a result, degradation of habitat quality in combination with loss of biodiversity are the major consequences. Along the Romanian Danube River, large parts of former wetlands, lakes and braided river reaches have disappeared, with the wetland Fundu Mare Island representing one of its last remains. In recent years, a reduction of the water levels and willow encroachment into the aquatic zone were observed, affecting the high biological diversity of the island. In order to protect biodiversity, the implementation of restoration measures in Fundu Mare Island is investigated within the project Restoration of the aquatic and terrestrial ecosystems complex, from Fundu Mare Island, part of the Small Wetland of Brăila funded by EEA-grants. As part of the project, this work aims at the investigation of a number of restoration scenarios that allow conservation of biodiversity. The implementation of a two-dimensional numerical model was examined in Delft3D. Due to the time restrictions of the thesis and unforeseen problems during model calibration, a general investigation by the application of a simplified water balance approach was applied. Based on the results, it can be concluded that the water levels on the island can be positively influenced by the implementation of weirs. In order to meet the requirements regarding security, hydrological uncertainty, and ecological demands, the installation of the bag weir is recommended. The demands of fish in the area can be met by seasonal opening of the channels on the island to enhance water exchange and provide connectivity between Fundu Mare Island and the Danube. However, further research needs to be carried out to analyse the feasibility of the implementation with regard to the simplifications made in this approach
Reservoir Sedimentation Study for the Bunakha Hydro-electric Project
No full textThis thesis presents a study on the sedimentation of the reservoir of the Bunakha Hydro-electric Project in Bhutan. Although the Detailed Project Report for this peaking reservoir scheme has already been completed, it has been used for further and additional investigations related to reservoir sedimentation. The sediment inflow into the reservoir was determined through two independent studies: i) Application of Pacific Southwest Interagency Committee (PSIAC) and Revised Universal Soil Loss Equation (RUSLE) approach integrated with Geographic Information System (GIS), ii) Data analysis of available suspended sediment data of Tamchu gauging station.
The application of the PSIAC approach taking into account three different boundary conditions related to catchment properties resulted in estimates of the average annual sedimentation rate for the Bunakha catchment/watershed at the location of gauging station as 0.4 mm/year, 0.18 mm/year, and 0.63 mm/year, respectively.
The determination of sedimentation rates based on the RUSLE approach was implemented in a GIS and estimated in two stages. First, the annual soil loss was determined using the RUSLE Model and in the second stage, the Sediment Delivery Ratio (SDR) was applied to estimate sediment yield. Using three different empirical SDR-equations, the estimated average annual sedimentation rate at the gauging station location using this approach was 0.303 mm/year, 0.203 mm/year, and 0.226 mm/year, respectively.
The sediment load to the reservoir was also estimated from available data for the period 2009-2015 employing two approaches. In the first approach, the measured suspended sediment load was combined with bed load transport rates estimated from various computational approaches. In the second approach, both the suspended and bed load were computed. The average annual sedimentation rate resulted from these approaches ranged from 0.13-1.22 mm/year and that of bed load calculated ranged from 10-25% of the suspended sediment load.
The comparison of the results from the different approaches showed that the estimated sedimentation rate ranged from 0.13-0.63 mm/year. For the subsequent prediction of the reservoir sedimentation, a mean value of 0.50 mm/year was used taking into consideration a safety factor of 1.3 to account for potential extreme events resulting from landslides due to glacier lake outbursts. New Zero-capacity Elevation (NZE) determined with the application of Empirical Area Reduction method for 30, 50 and 70 years are 1908 m, 1926 m and 1944 m respectively indicating that even after 70 years of reservoir operation, the sediment deposit level will be well below the Minimum Draw Down Level (MDDL) if there is no flushing of the sediments. However, the sediment will be flushed during monsoon season with low level spillway sluice that will be installed at 1915 m, whereby sediment will never rise beyond this level (DHPS, 2013). The perspective downstream impact due to reservoir sedimentation were studied through literature reviews
Ecosystem restoration at Fundu Mare Island in the Inner Danube Delta near Braila (Romania) - Hydrodynamic optimisation
Full text linkWithin the last century, the extensive implementation of engineering measures in European rivers has caused significant changes in river hydrology, water quality and local ecology, inducing major impact on the environment of wetlands. As a result, degradation of habitat quality in combination with loss of biodiversity are the major consequences. Along the Romanian Danube River, large parts of former wetlands, lakes and braided river reaches have disappeared, with the wetland Fundu Mare Island representing one of its last remains. In recent years, a reduction of the water levels and willow encroachment into the aquatic zone were observed, affecting the high biological diversity of the island. In order to protect biodiversity, the implementation of restoration measures in Fundu Mare Island is investigated within the project Restoration of the aquatic and terrestrial ecosystems complex, from Fundu Mare Island, part of the Small Wetland of Brăila funded by EEA-grants. As part of the project, this work aims at the investigation of a number of restoration scenarios that allow conservation of biodiversity. The implementation of a two-dimensional numerical model was examined in Delft3D. Due to the time restrictions of the thesis and unforeseen problems during model calibration, a general investigation by the application of a simplified water balance approach was applied. Based on the results, it can be concluded that the water levels on the island can be positively influenced by the implementation of weirs. In order to meet the requirements regarding security, hydrological uncertainty, and ecological demands, the installation of the bag weir is recommended. The demands of fish in the area can be met by seasonal opening of the channels on the island to enhance water exchange and provide connectivity between Fundu Mare Island and the Danube. However, further research needs to be carried out to analyse the feasibility of the implementation with regard to the simplifications made in this approach
Reservoir Sedimentation Study for the Bunakha Hydro-electric Project
Full text linkThis thesis presents a study on the sedimentation of the reservoir of the Bunakha Hydro-electric Project in Bhutan. Although the Detailed Project Report for this peaking reservoir scheme has already been completed, it has been used for further and additional investigations related to reservoir sedimentation. The sediment inflow into the reservoir was determined through two independent studies: i) Application of Pacific Southwest Interagency Committee (PSIAC) and Revised Universal Soil Loss Equation (RUSLE) approach integrated with Geographic Information System (GIS), ii) Data analysis of available suspended sediment data of Tamchu gauging station.
The application of the PSIAC approach taking into account three different boundary conditions related to catchment properties resulted in estimates of the average annual sedimentation rate for the Bunakha catchment/watershed at the location of gauging station as 0.4 mm/year, 0.18 mm/year, and 0.63 mm/year, respectively.
The determination of sedimentation rates based on the RUSLE approach was implemented in a GIS and estimated in two stages. First, the annual soil loss was determined using the RUSLE Model and in the second stage, the Sediment Delivery Ratio (SDR) was applied to estimate sediment yield. Using three different empirical SDR-equations, the estimated average annual sedimentation rate at the gauging station location using this approach was 0.303 mm/year, 0.203 mm/year, and 0.226 mm/year, respectively.
The sediment load to the reservoir was also estimated from available data for the period 2009-2015 employing two approaches. In the first approach, the measured suspended sediment load was combined with bed load transport rates estimated from various computational approaches. In the second approach, both the suspended and bed load were computed. The average annual sedimentation rate resulted from these approaches ranged from 0.13-1.22 mm/year and that of bed load calculated ranged from 10-25% of the suspended sediment load.
The comparison of the results from the different approaches showed that the estimated sedimentation rate ranged from 0.13-0.63 mm/year. For the subsequent prediction of the reservoir sedimentation, a mean value of 0.50 mm/year was used taking into consideration a safety factor of 1.3 to account for potential extreme events resulting from landslides due to glacier lake outbursts. New Zero-capacity Elevation (NZE) determined with the application of Empirical Area Reduction method for 30, 50 and 70 years are 1908 m, 1926 m and 1944 m respectively indicating that even after 70 years of reservoir operation, the sediment deposit level will be well below the Minimum Draw Down Level (MDDL) if there is no flushing of the sediments. However, the sediment will be flushed during monsoon season with low level spillway sluice that will be installed at 1915 m, whereby sediment will never rise beyond this level (DHPS, 2013). The perspective downstream impact due to reservoir sedimentation were studied through literature reviews
Morphologische Entwicklung von mäandrierenden Flüssen bei unterschiedlichen Abflussregimes
Full text linkThis PhD thesis investigates the effects of changing discharge regimes on the morphological development of meandering rivers. The reduction of discharge causes bed morphology and planform changes in alluvial rivers with erodible banks, and restoring the discharge may alter the existing morphology, leading to a new (so far unpredictable) river course. The present thesis explores the capability of the open-source software Delft3D to simulate the adaption of both planform dynamics and bed topography to changed discharge regimes. A specific reach in the Dhaleshwari River (Bangladesh) is taken as a case study as it provides relevant data for model validation.
Both two-dimensional (2D) and three-dimensional (3D) modelling approaches were applied. The 3D model, which was calibrated against measured 3D flow data, was used for predicting bed level changes over a one-year period. The simulated morphological changes showed a certain degree of resemblance with the available field data, but the required computational time prevented further analyses. Therefore, a 2D model, in which the parameterization of the 3D flow effect was validated against curved flume data, was used to simulate the morphological development for different discharge scenarios over a 10-year period.
The results of the simulations revealed that the 2D model could predict scour depth, bank erosion, and riffle-pool sequences under both constant and varying discharge scenarios. However, the prediction of channel bankfull width showed some deficiencies. The simulations with varying discharge demonstrated a more realistic prediction of the meander planform than the simulations with constant discharge. The conclusion from this research is that a 2D modelling approach, in combination with a time-varying discharge, can be used to simulate the natural dynamics of meandering rivers, both in terms of the development of bed topography and channel planform. The results further revealed that a discharge magnitude of about 90% of the bankfull discharge represents the dominant discharge, and that the meander wavelength increases with the discharge magnitude. The results of the simulation for time-varying discharge records revealed that larger floods favor enlargement of meander wavelength and smaller floods favor shortening of meander wavelength during the first 50% of the simulation period. However, after the first 5-year period, the meander wavelength becomes nearly unresponsive to altered high- and low- floods.Diese Doktorarbeit untersucht die Auswirkungen eines sich ändernden Abflussregimes auf die morphologische Entwicklung mäandrierender Flüsse. Eine Verringerung des Abflusses führt zu Veränderungen der Flussschlauchmorphologie und der Laufform alluvialer Flüsse mit erodierbaren Bänken und die Wiederherstellung des Abflusses kann zu einem neuen (bisher unvorhersehbaren) Flussverlauf führen. Die vorliegende Arbeit beschäftigt sich mit der Frage, in wie weit die Open-Source-Software Delft3D in der Lage ist, die Anpassung sowohl der Laufformdynamik als auch der Sohlentopographie bei sich ändernden Abflussregimes zu simulieren. Als Fallstudie diente ein Flussabschnitt des Dhaleshwari Flusses in Bangladesch, für den relevante Daten für die Modellvalidierung vorlagen.
Zur Modellierung wurden sowohl zweidimensionale (2D) als auch dreidimensionale (3D) Ansätze herangezogen. Das mittels gemessener 3D-Strömungsdaten kalibrierte 3D-Modell wurde zur Vorhersage der Änderungen des Sohlniveaus über einen Zeitraum von 1 Jahr herangezogen. Die Ergebnisse der Simulationen zeigten eine gewisse Ähnlichkeit der morphologischen Veränderungen mit den Felddaten, aber die erforderliche Rechenzeit verhinderte weitere Analysen. Daher wurde das 2D-Modell verwendet, für das die Parametrisierung des 3D-Strömungseffekts anhand von Laboruntersuchungen validiert wurde. Mit diesem Modell wurden verschiedene Abflussszenarien über einen Zeitraum von 10 Jahren simuliert.
Kolktiefe, Ufererosion und Riffle-Pool-Sequenzen konnten mit dem 2D-Modell modelliert werden, wobei sich jedoch Abweichungen bei der bordvollen Breite ergaben. Die Simulationen mit variierendem Abfluss zeigten eine realistischere Vorhersage der Laufform als die Simulationen mit konstantem Abfluss. Diese Ergebnisse verdeutlichen, dass ein 2D-Modellierungsansatz in Kombination mit einer Ganglinie verwendet werden kann, um die natürliche Dynamik der Sohlentopographie und Laufform von mäandrierenden Flüssen zu simulieren. Die Ergebnisse zeigten ferner, dass ein Abfluss von etwa 90% des bordvollen Abflusses den bettformenden Abfluss darstellt und dass die Mäanderwellenlänge mit dem Abfluss zunimmt. Die Ergebnisse der Simulation mit Ganglinien zeigten, dass größere Hochwasserereignisse eine Vergrößerung und kleinere eine Verkürzung der Mäanderwellenlänge während der ersten 50% der Simulationsperiode begünstigen. Nach den ersten 5 Jahren reagiert die Mäanderwellenlänge jedoch kaum mehr auf veränderte Hoch- und Niedrigwasser
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