| Author | Samad, Mustafa Ataus |
| Call Number | AIT Thesis no.WM-96-02 |
| Subject(s) | Morphology--Bangladesh--Jamuna river
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. WM-96-02 |
| Abstract | Prediction of short term morphological changes in a river system requires that river
flow and sediment distribution patterns are estimated with considerable accuracy. These two,
again, are dependant on the bed roughness conditions, viz., mechanism of turbulence
dissipation. In a two dimensional morphological model it is, therefore, required that the
variation in bed roughness is predicted with sufficient degree of accuracy.
The bed roughness character of the Jamuna river has been investigated in the present
study in connection with flow, sediment transport and bedform parameters. High variation in
the Chezy coefficient has been observed which is mainly contributed by the bedforms present
at the bed. The Chezy coefficient has been found to depend strongly on the energy gradient,
suspended sediment concentration and on flow stages responsible for modifying the bedforms.
Comparison with observed variation suggested none of the existing roughness
prediction methods could successfully reproduce the high variability of Chezy coefficient.
Therefore, two new simple prediction methods have been proposed those could be used in two
dimensional morphological computation. Verification of proposed equations showed that over
80% data falling in an accuracy factor range of 0.7 to 1.3.
Proposed equations have been applied in a two dimensional flow model and in
sediment transport computations. Considerable accuracy in flow distribution has been
achieved with Cehzy coefficient assessed from proposed equations. Although significant
variation of exponent 'n' in sediment transport formulations has been observed, however,
transport rates are generally less affected considering the high uncertainty associated with
such predictions. |
| Year | 1996 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. WM-96-02 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Suphat Vongvisessomjai; |
| Examination Committee(s) | Kyotoh, Harumichi;Sutat Weesakul;Paudyal, Guna Nidhi; |
| Scholarship Donor(s) | DANIDA; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1996 |