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Morphololgical computations of a cascade system of dams using Delft3D-FM coupled with a real-time control tool
This paper presents a detailed hydraulic and morphological study of a cascade system of dams, located in Marsyangdi River in Nepal. Firstly, a severe morphological problem in one of the dams, namely Middle Marsyangdi Hydropower Project (MMHPP), was studied. We revealed one of the key reasons of the problem, which is related to the ignorance of large- and meso-scale morphological feature of the river while selecting the site. Secondly, the sedimentation process at the reservoir was replicated using a two-dimensional morphological model, namely Delft3D-Flexible Mesh (D-FM) coupled with Real-Time Control (RTC) tool to simulate reservoir gate operation. We attempted to incorporate downstream dam in the model, namely Marsyangdi Hydropower Project (MHPP), to simulate synchronized operation and its morphological impact. The effect of synchronized operation of two dams was assessed by simulating different synthetic flushing scenarios. Sensitivity of two different sediment transport formulae (Ashida-Michiue and Engelund-Hansen) on the model results was assessed as well. Given a rapid modelling exercise of such complex system using D-FM, the results can be regarded as satisfactory. They showed consistent model behaviour and observed trend despite the complexity involved in morphological modelling with synchronized operation of two dams. The study can further be improved in case more data and information are available. The model can also be applied to optimize dam operation considering morphological and ecological impacts on downstream reach.
A new geotechnical centrifuge at Deltares, Delft, the Netherlands
A new geotechnical centrifuge has been commissioned by Deltares, Delft, The Netherlands, as a replacement of the previous facility, which has expended its serviceable life. The new centrifuge is an Actidyn C72-31 beam type centrifuge, and has a 260 g-tonne capacity and a platform radius of 5.0 m. The platform can house test set-ups with dimensions up to 1.2 m × 1.2 m × 1.2 m (length × width × height). The data-acquisition system is supplied by HBM and has 40 channels with a sampling rate of up to 100 kHz. Two high speed cameras and four monitoring cameras are available for imaging. A 4-axis robotic system allows in-flight excavation and installation operations. The centrifuge is fully prepared for later installation of an earthquake simulator. Supporting facilities consist of a clay mixer and a consolidation frame. This paper details the choices made leading to this centrifuge, the specifications of the centrifuge and supporting facilities.
Proceedings of the 4th European Conference on Physical Modelling in Geotechnics - ECPMG 2020 (Lulea, Sweden / Zoom, 7-8 September 2020)
Large‑scale stochastic flood hazard analysis applied to the Po River
Reliable hazard analysis is crucial in the flood risk management of river basins. For the floodplains of large, developed rivers, flood hazard analysis often needs to account for the complex hydrology of multiple tributaries and the potential failure of dikes. Estimating this hazard using deterministic methods ignores two major aspects of large-scale risk analysis: the spatial–temporal variability of extreme events caused by tributaries, and the uncertainty of dike breach development. Innovative stochastic methods are here developed to account for these uncertainties and are applied to the Po River in Italy. The effects of using these stochastic methods are compared against deterministic equivalents, and the methods are combined to demonstrate applications for an overall stochastic hazard analysis. The results show these uncertainties can impact extreme event water levels by more than 2 m at certain channel locations, and also affect inundation and breaching patterns. The combined hazard analysis allows for probability distributions of flood hazard and dike failure to be developed, which can be used to assess future flood risk management measures.
Groundwater quality in Dutch water management
Good groundwater quality is essential for numerous receptors in the Netherlands, such as drinking water supply, aquatic and terrestrial ecology, and water supply for agriculture and industry. In the meantime, the anthropogenic use of the water system affects the groundwater quality. We are challenged to use our water resources in a sustainable way. This paper elaborates on a number of examples of our projects on groundwater quality for Dutch water management.
Study of morphological impact and optimization of longitudinal dams in the river Waal by using Delft3D numerical model
Longitudinal dams are proposed to be constructed in the Rhine branches as an alternative or addition to groyne lowering. The measure has been proposed to provide more room for the flood water, as well as to improve navigability. In this study the Delft3D morphological model has been applied to study the morphological impacts of these longitudinal dams, and to optimize them for minimizing inconvenient sedimentation patterns.
Profiling resilience and adaptation in mega deltas : a comparative assessment of the Mekong, Yellow, Yangtze, and Rhine deltas
River deltas and estuaries are disproportionally-significant coastal landforms that are inhabited by nearly 600 M people globally. In recent history, rapid socio-economic development has dramatically changed many of the world’s mega deltas, which have typically undergone agricultural intensification and expansion, land-use change, urbanization, water resources engineering and exploitation of natural resources. As a result, mega deltas have evolved into complex and potentially vulnerable socio-ecological systems with unique threats and coping capabilities. The goal of this research was to establish a holistic understanding of threats, resilience, and adaptation for four mega deltas of variable geography and levels of socio-economic development, namely the Mekong, Yellow River, Yangtze, and Rhine deltas. Compiling this kind of information is critical for managing and developing these complex coastal areas sustainably but is typically hindered by a lack of consistent quantitative data across the ecological, social and economic sectors. To overcome this limitation, we adopted a qualitative approach, where delta characteristics across all sectors were assessed through systematic expert surveys. This approach enabled us to generate a comparative assessment of threats, resilience, and resilience-strengthening adaptation across the four deltas. Our assessment provides novel insights into the various components that dominate the overall risk situation in each delta and, for the first time, illustrates how each of these components differ across the four mega deltas. As such, our findings can guide a more detailed, sector specific, risk assessment or assist in better targeting the implementation of risk mitigation and adaptation strategies.
Mixing social media analysis and physical models to monitor invasive species
Invasive species, such as jellyfish, cause economic losses in millions annually. Therefore, being able to accurately monitor and predict jellyfish is vital to several stakeholders (e.g. tourism, fishery, government). A potential tool to help these communities could be by combining a biophysical drift model with a processing chain for soft information fusion which would predict jellyfish occurrences. To guarantee accuracy, the model needs to be validated by actual data. This data can be gathered from citizens who reported jellyfish sightings on social media or a dedicated citizen science mobile app. As the information provided by citizens is spread among numerous atomic reports, we use a platform for soft information fusion to aggregate and fuse these reports into a single information network. The soft information fusion platform relies on the use of domain knowledge, provided through an ontology. The information network can then be queried to extract relevant features to validate the jellyfish drift model. Future work includes the initialisation of the model with soft information, as well as making use of the different levels of quality of the reports provided by citizens, in order to assess the quality of the fused information.
Fusion 2020 - 23rd International conference on information fusion : virtual conference (July 6-9, 2020)