Supervisors: Adina Moraru, Nils Rüther, Oddbjørn Bruland
Project: World of Wild Waters (WoWW)
, Knut Alfredsen
Hydraulic modelling have become the most important tool for addressing consequences of flood and human interventions in rivers. These models are used to estimate flood levels and forces of water at dimensioning floods and thus where people safely can build their houses and where infrastructures safely can be placed. They are used to analyze habitat conditions or changes in hydraulic regime in a river due to a planned interventions in a river. Thus, these models have a high socio economic impact and there is a strong need of competency and deep knowledge of how and where to use these models.
More advanced models, more topographical information and computational power allows for higher resolution and more precise simulations. The uncertainty related to these simulations is nevertheless high and calibration to observed water levels at certain discharges is necessary to ensure a reliable simulation. In most Norwegian rivers this information is hard to access and this limits the use of the models. The roughness parameters in the model is traditionally tuned to get a good fit between observed and simulate water levels. But when the resolution of the topography and the bathymetry in the model is high and precise enough to describe the roughness of the river in detail, what function and impact will then the roughness parameters have in the model?
The questions this thesis will try to answer is
- "Can a high enough resolution of the topographical model describe the roughness of the river bed and flood area good enough to eliminate the need for calibration?"
- "What role do the roughness parameter play when the topographical resolution describes the impact of roughness?"
- "What is the uncertainty when using hydraulic models in rivers without calibration data"
The thesis is well suited for a combination with a project in the fall. The work will consist of
- Collecting calibration data for one or more rivers during fall if combined with a project or spring if not
- Setting up hydraulic models for the rivers
- Testing and calibrating the model with different resolutions
This will give a deep understanding of the hydraulic models, their applicability and limitations. There is a high demand for this competency in the society, among consultants and governmental institutionsThe prediction accuracy required to implement risk alleviation measures is a core issue when addressing flood risk assessment. This thesis aims at evaluating the impact of variable mesh refinement in the precision of hydrodynamic models compared with full hydrodynamic simulations. The case study for this thesis will be a recently documented flood in a Norwegian river. The final outcome should be a decision tree for optimal model design.
Figures show documentation on a recent flood event (Utvik, 2017) and topography representation at different grid resolutions (Xia et al., 2019).
Implications of this master thesis: improving flood simulations in steep rivers through more efficient simulation models. The gathered knowledge will help develop a methodology that will increase flood simulation efficiency (e.g. improving simulation speed without truly compromising on the precision of the outcome), eventually contributing to the state-of-the-art of real-time fluid simulations. The resulting scenarios will be implemented into a visualization platform (e.g. Virtual Reality), further used in decision-making.
The student involved in this project should have interest in numerical modelling and natural hazards, as well as be inclined to research on topography representation and different GIS tools.
The candidate must be familiarised with hydraulics and fluid dynamics.