| Author | Hlwan Moe |
| Call Number | AIT Thesis no. GE-00-22 |
| Subject(s) | River engineering
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-00-22 |
| Abstract | Laboratory experiments were conducted to determine the effect of short cutting
and blocking river bends on river morphology. A total of four experiments were done
using sand sediment of mean diameter O. l 9mm for two different flow discharges. The
meander geometry used for the laboratory experiment has a similar pattern as of the Chao
Phraya River near Bangkok Port.
The measured relationships between the bed level and water level changes with
time along meander path and the shortcut path are compared with the computed values
for the numerical HEC-6 morphological model. The velocity and the depth along the _
meander path and the shortcut path at the starting and after five to six hours are also
plotted. All the plots show the asymptotic approach to the stable condition after 320
minutes. Under the same boundary condition as in the experiments, the HEC-6 model
shows good agreements with the experimental results.
Movement of sediment bed step was observed immediately after the river
meander shortcut. Erosion occmTed at the upstream of shortcut and deposition occurred
at the downstream of the shortcut. Due to these processes, a step was observed which
originated from middle of the shortcut and moved downstream until the end. The height
of bed step movement decreased with time and distance. The step is moving towards
downstream and nearly vanished at the downstream end.
The plot against distance and time from the middle of the shortcut towards
downstream shortcut shows the path of the step movement, which continously changes
with distance and time. The inverse of the slope of this path is known as the celerity of
the sediment bed step. It is directly proportional to the channel width and the sediment
load and inversely proportional to the water depth.
Immediately after the shortcut, there is a level difference between the upstream
and the downstream of the shortcut. As such water depth at upstream is smaller
downstream. Having the same channel width and similar sediment discharge between
these two stations, the celerity at upstream is greater than downstream. The celerity
decreased with time and distance after shortcut. |
| Year | 2001 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-00-22 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Tawatchai Tingsanchali; |
| Examination Committee(s) | Izumi, Norihiro;Miura, Kinya; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2001 |