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ABSTRACT
As a result of increasing economic growth of the country, areas within
river catchment are being developed for commercial, industrial and housing
purposes. Effect of this rapid urbanization has accelerated impact on the
catchment hydrology and geomorphology. These developments have caused
dramatic increase in the surface runoff and the behavior of sediment
output, hence resulting in higher sediment yield.
Since any flood mitigation works would likely involve channel
modification, so knowledge of predicting the geometry changes as a result
of sediment transport movement is significant and necessary. By using
appropriate method, channel stability and river equilibrium can be
achieved.
Intensive literature review has been made on several aspect of river
morphology such as characteristics of natural river, channelization works
and their impact, and conservation concept toward restoration of
channelized river.
Two catchments namely Raia River at Simpang Pulai, Ipoh and Pari River at
Ipoh, with different land use and development were chosen for this study.
Raia River represents a natural river while Pari River represents a
channelized river.
Several gauging stations were identified based upon the river
characteristics such as straight reach and bend. Six stations for Raia
River and four stations for Pari River were selected. Sediment sizes were
identified by collecting bed and bank materials from each station. Surveys
of existing cross section and water level measurements were carried out
for comparison purposes with the morphological changes predicted by
FLUVIAL-12 and three different method of designing stable channel.
Comparisons on the three empirical design methods including maximum
velocity, tractive force and regime method (Simons and Albertson, 1960)
with mathematical model (FLUVIAL-12) using field’s data were carried out
in order to choose the appropriate method which will minimize the
morphological changes in river channel. The results from the mathematical
model (FLUVIAL-12) that comprises component of water and sediment routing,
indicates channel changes that agrees well with the characteristics of a
dynamic river. FLUVIAL-12 is also capable of predicting channel
instability effect such as erosion and sedimentation at straight reach and
bend for both Raia and Pari River.
Simulation results based upon FLUVIAL-12 also indicate that Raia River can
be conserved as a natural river by maintaining cross section with a side
slope of 1:2. By ensuring the Manning’s roughness coefficient to be
0.025 and a cross section with a side slope of 1:2, Pari River can be
restored as a natural river without the concrete bank.
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