Minh Tuan Bui

Disputas - Minh Tuan Bui

Master of science Minh Tuan Bui will on August 26th at 12.15 publically defend his PhD degree in science.

Title of the PhD thesis:

"Hydrological Modelling and Climate Change Impact Assessment on Future Floods in the Norwegian Arctic Catchments"

Abstract:

Climate change is expected to alter the hydrological cycle in the Arctic, which would result in the increase in intensity and frequency of hydrological extreme events such as flooding. Noticeably, the changes in flooding due to climate change would severely affect human life, infrastructures, the environment, ecosystem, and socio-economic development in the impacted areas. Hydrological models are state-of-the-art tools for assessing the impact of climate change on hydrological processes. However, performing hydrological simulation/projection in the Arctic is challenging because of the complex hydrological processes and data-sparse features in the region. In consideration of those issues, this PhD research aims: (1) to assess the performances of hydrological models in the Arctic, (2) to investigate the alternative weather inputs for running the hydrological models in the Arctic region with scattered monitoring data, (3) to evaluate the effects of the models’ structure and parameterization and the spatial resolution of weather inputs on the results of hydrological simulations, and (4) to project future hydrological events under climate change impacts using the current hydrological model, and analyse the reliability/uncertainty of the projection. To fulfil the research’s objectives, several methodologies were applied. Firstly, a comprehensive review was conducted to address the current capacities and challenges of twelve well-known hydrological models, including surface hydrological models and subsurface hydrological models/groundwater models/cryo-hydrogeological models. These models have previously been applied or have the potential for application in the Arctic. Next, the physically based, semi-distributed model, SWAT (soil and water assessment tool), was selected as a suitable model, among other potential models, to assess its performance for hydrological simulations and to verify the potential application of reanalysis weather data. Moreover, the SWAT model was coupled with multiple ensemble global and regional climate models’ (GCM_RCM) simulations to project the future hydrological impacts under climate change (in 2041-2070). The study areas were mainly focused in the Norwegian Arctic catchments.
This study found that both surface hydrological models and subsurface hydrological models/groundwater models/cryo-hydrogeological models have their capacities and limitations regarding dealing with complex hydrological processes in the Arctic. Besides, the selection of suitable models also depends on the targets and current conditions (e.g., available inputs, timing, funding, etc.) of each study. The SWAT model demonstrated considerable capacity for surface hydrological simulation under different temporal resolutions (e.g., monthly and daily simulation) in Norwegian Arctic catchments with variations in geographical distributions, latitudes, catchment’s scales, and dominant hydrological regimes. However, the SWAT’s performance varied among catchments as well as among sub-catchments within a large catchment. This explained the heterogeneous effects of catchments’ characteristics, variation in local climate condition and dominant hydrological regimes in the Arctic environment. This study also found that the Climate Forecast System Reanalysis (CFSR) data had great capacity to drive the SWAT for hydrological simulations in the Norwegian Arctic catchments. Thus, the reanalysis products, like the CFSR, could be an alternative weather input to run the hydrological model in case of the existing monitoring networks being scattered. By altering model structures (e.g., number and size of sub-catchments, land use compositions and catchment characteristics, through the catchment delineation process), model parameters (through the calibration process), and quality of weather input (e.g., spatial resolution) for the SWAT, this would somewhat affect the results of hydrological simulations (e.g., annual mean values and spatial variation of snowmelt runoff, water balance components and streamflow (including peak flow)).
Under climate conditions in the near future period (2041-2070), the key projections for the Norwegian Arctic would be: (1) flood magnitudes would increase in the snowmelt-dominated catchments and decrease in the rainfall-dominated catchments, while the catchment with a mixed rainfall/snowmelt regime would experience both increase and decrease (only small flood) patterns; (2) extreme flood events would occur more frequently in the northern and southern catchments, while such behaviours would be the opposite in the inland catchments (with dominant snowmelt) in the centre of the Norwegian Arctic; (3) the changes in future extreme flood events would be more complicated in the rainfall-dominated catchment and near the coast due to high variation of future rainfall in this area; (4) small flood events would experience the opposite behaviours compared to the extreme floods. Finally, in the climate-hydrology modelling chain for flood projections, uncertainties from the ensemble climate models’ simulations were found to be larger than those from the hydrological SWAT model. In addition, levels of uncertainties were varied greatly regarding catchments’ scales and the dominant flood regimes.

The thesis is published and available in Munin

Supervisors

  • Asociate Professor Jinmei Lu, IIS, UiT, (main supervisor)
  • Dr. Tiina Leiviskä, Department of Chemical Process Engineering, University of Oulu (co-supervisor)
  • Associate professor Hassan Khawaja, IVT-fak, UiT (co-supervisor)
  • Dr. Linmei Nie, Managing Director, Centre for Sustainable Development and Innovation of Water Technology (CSDI), Oslo, Norway

Evaluation committee

  • Professor Chong-Yu Xu, Department of Geosciences, University of Oslo (1. Opponent)
  •  Senior Lecture Linus Zhang, Department of Building and Environmental Technology, Division of Water Resources, Engineering, Lund University, Sweden (2. Opponent)
  • Associate Professor Anne Mai Ersdal, IVT fak, automation and process technology, UiT (intern member and leader of the commitee)

Leader of the defense: Professor Javad Barabadi

Links to the trial lecture and defense will be possible to open when the live stream begins. If you haven`t clicked the link to the folder before it begins, refresh the web browser for them to become visible. If you have clicked the link to the trial lecture or defense before it has started, it will open automatically when the stream begins. 

Link to folder which contains trial lecture and defense

The trial lecture starts at 10.15 august 26th

Trial lecture

The defense starts at 12.15 august 26th

Defense

When: 26.08.22 kl 12.15–16.00
Where: Realfagsbygget B302, store auditorium
Location / Campus: Digitalt, Tromsø
Target group: Ansatte, Studenter, Besøkende, Inviterte
Contact: Eirik Derås Verlo
E-boastta: eve012@uit.no
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