Boulder and water surface topography in steep torrent experiment
Date Issued
2015
Date
2015
Author(s)
Yu, Peng
Abstract
Step pool is a kind of channel morphology of steep mountain streams which is similar to stairs in the bed of the stream. In this thesis we use field survey data and laboratory experiment to investigate the step pool morphology of Shen-Mu Torrent, Central Taiwan, including its formation and current degree of stability. Digital photogrammetry using flash-synchronized multiple views is used to experimental water surfaces in addition to be topography. We conduct experiment in both rigid bed and mobile bed conditions. In rigid bed model experiment, we built a 1/25 scale model of Shen-Mu river and supplied a 50-year flood to determine the flood surface and check photogrammetry measurements against pin gage data. The results of this experiment demonstrate that photogrammetry can be used for water surface observations. The objective of mobile bed experiment is to investigate the formation and stability of step pool topography. We design three discharges and five cases with different particle mixing ratio. The results show that channel bed will evolve when subject to a record discharge, but gradually become stable to floods of this and lower magnitudes. Among the five mixing cases, the clearest step pool morphology is obtained when the volume of small particles is 7 times the volume of large particles.
Subjects
step pool
photogrammetry
Shen-Mu Torrent
water surface observation
flash-synchronized multiple views
Type
thesis
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