Lee, Wai Hong
(2013)
Evaluation Of Sediment Size For
Flow Estimation In Alluvial
Channel.
Masters thesis, Universiti Sains Malaysia.
Abstract
Flow estimation in alluvial channel is one of the most common practices in river
engineering. A lot of methods are introduced in water resources field towards increasing
the accuracy of determining the roughness coefficient as well as estimating the flow
based on sediment size. However, most of these studies are mainly based on idealized
laboratory conditions such as uniform flow and uniform sedimentation. These derived
methods do not satisfy for channel with irregular shapes. The interest of this study is to
determine the roughness coefficient in term of choices of sediment size towards non
uniform sedimentation distribution in irregular channel. A few relevant well known
equations are used in evaluating and comparing the flow resistance estimation. In this
study, a total number of 167 sets of field data were collected. 31 sets data which
collected from Sungai Jawi were used to investigate the hydraulic characteristics of
Sungai Jawi. Another 143 sets field data of eight selected rivers collected from previous
studies were used to evaluate the accuracy of existing well known equations for
determining the flow resistance. Throughout the analysis, none of the method estimates
the flow accurately. Sediment mode size, d65, was proposed to represent the sediment
mixture for flow estimation purpose. At the end of this study, an equation had been
developed based on the total 167 sets of data. This equation is intended to determine the
flow resistance with the ratio of hydraulic radius and averaged flow depth to the
sediment mode size. The results show an improvement to the discrepancy of flow
estimation based on the applicable d65.
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