University of Twente Student Theses


Simulating spatial and temporal variation of snow cover in the Black Brook Watershed using imWEBs

Veelen, Thomas van (2014) Simulating spatial and temporal variation of snow cover in the Black Brook Watershed using imWEBs.

Abstract:The imWEBs model has recently been developed by the Watershed Evaluation Group of the University of Guelph. It is a spatially based model with the aim of simulating the spatial and temporal distribution of the snow cover. In this project the specific objective has been to calibrate the snow redistribution module with the help of data of the winter of 2012 and to provide comments and suggestions for improvements. A literature study, data analysis, calibration and sensitivity analysis have been done to increase understanding of the snow redistribution process and to achieve the best calibration results with the information available. However the calibration results turned out to be not good enough to use in practice. Although the model managed to increase the Nash-Sutcliff coefficient form -0.18 to 0.27 and the general patterns seemed fine, this is still a low value. Moreover the model seems to depend only on land use and wind speed. Especially the wind speed seems very important. It is however also very sensitive, while there are doubts regarding the reliability of the data. Another problem is that the model appears to redistribute too much snow to attractive spots, which causes not enough variation in the less attractive areas. There is however more research required to confirm this. Other problems are the lack of a clear relation between snow water equivalent and both slope and curvature and the fact that only the climate properties of two days were taken into account. Therefore it is recommended to do a new calibration with more extensive data. Firstly it is advised to increase the number of sample points, especially in areas that are attractive according to the model, to analyse the hypothesis about the models tendency. Secondly it is recommended to make an on field estimate of slope and curvature to confirm the slopes and curvatures calculated by the imWEBs model. Thirdly it is recommended to write down the times the samples were taken to estimate the accuracy of the sample data. Finally it is recommended to increase the number of weather stations to improve analyse the wind regime with more detail and to improve the accuracy of the wind speed data. Furthermore it is also recommended to make some changes in the model. Firstly it is recommended to implement a factor which determines what percentage of the day the wind speed threshold value is met. This will improve the simulation of the amount of snow that gets redistributed on a day. Secondly it is recommended to investigate the option of implementing a flux based model to improve the simulation of the actual process, although this will require a lot of work to rewrite the model and it might decrease the possible resolution of the model. When all recommendations are implemented a better result is expected. Because although the calibration did not succeed during this project, useful lessons can be learnt from it. A future project might go smoother when the recommendations are adopted.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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