| Author | Othman, Muhammad Akhir Bin |
| Call Number | AIT Thesis no. WA-85-17 |
| Subject(s) | Sand-bars
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| 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 |
| Abstract | Shoaling of harbour entrances is a problem to navigation. It makes the entrance channels shallow, and thus limits the draft of vessels that can enter the harbour. Traditional methods of overcoming this problem, by groyne construction and dredging, are not very successful. The construction of groynes usually result in erosion downcoast and accretion upcoast of the groynes. After a certain time, the sand finds its way into the harbour entrance, necessitating costly maintenance dredging. A natural means of sand bypassing, using the available wave energy to transmit the sand across the entrance of by shifting the sand offshore can be achieved by a cranked jetty. A study is carried out, using hydraulic models, to find the most effective configuration of cranked jetties for transmitting sand across harbour entrances. The criteria used are that the amount of deposition at the harbour entrance and the scouring downcoast of the jetty should be minimized. The angle of incidence of the prevailing waves to the offshore arm is varied in the experiment. From the results it was found that for the most favorable short crested wave system for sand transmission to occur, the angle of incidence of the prevailing waves to the offshore arm must be large. There is an optimum angle where the sand deposition at the entrance and the scouring downcoast are minimum. However, though the rate of deposition at the entrance is small for this angle, the harbour will close quickly, due to the width of the entrance being narrow, and the depth shallow. Thus a compromise must be found in determining the optimum configuration, after considering the cost of dredging and the duration that the harbour is needed to be kept openfor. |
| Year | 1984 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Water Resources Research Engineering (WA) |
| Chairperson(s) | Suphat Vongvisessomjai |
| Examination Committee(s) | Tawatchai Tingsanchali ;Prida Thimakorn |
| Scholarship Donor(s) | U.S. ASEAN |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1984 |