| Author | De Silva, Manimeldura Sampath |
| Call Number | AIT Thesis no.WA-94-13 |
| Subject(s) | Silt--Thailand, Southern
|
| 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 |
| Abstract | This study focuses on the sediment transport phenomenon along the east coast of southern
Thailand. The problem of beach erosion and resulting siltation of the harbors and shoaling of
river mouths are investigated.
The eastern coastline of southern Thailand is changing from time to time. The high
alongshore sediment transport rates generate by northeast monsoon waves are identified as the
main cause. The sediment transport rates along the eastern coastline from Songkla lagoon to
Pak Panang bay are calculated using CERC'84 and Hanson'91 methods. The CERC'84 method
depends on the deepwater wave characteristics, where as the Hanson' 91 method depends on
the breaking wave characteristics. The RCPWAVE Model (Regional Coastal Processes Wave
Model) developed by U.S. Army Crops of Engineers in 1986 is used to find the breaking wave
characteristics. Since wave data exhibits a significant variation with respect wave direction,
height, period and speed it is practically not feasible to use all the data to find sediment
transport rates in Hanson' 91 method. A new method based on equivalent sediment transport
rate is introduced to compute the representative wave characteristics. The method proposed by
Watanabe (1982) is used to evaluate the sediment transport rate out-side the surf zone. The
RCPW A VE Model results are integrated with the numerical method proposed by Horikawa
(1984) to find the morphological changes in sea bed due to sediment transport out-side the surf
zone. The siltation of harbors and shoaling of river mouths are analyzed critically. The
resulting accretion at the updrift side of the Songkla jetty is calculated analytically using the
one line model proposed by Pelnard-Considere.
From this study it is found that the alongshore sediment transport inside the surf zone as
the main cause of morphological changes of the southern coastline of Thailand. The crossshore sediment transport due to direct action of wave is found to be negligible. According to
the Pelnard-Considere's one line model, sediment would bypass the 700m Songkla jetty after
40 years. But in actual case, sediment bypassed the jetty only after 9 years of construction.
Since the updrift side of Songkla jetty is very shallow, in actual practice it takes shorter period
to bypass the jetty than the time predicted by theory. |
| Year | 1994 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Water Resources Research Engineering (WA) |
| Chairperson(s) | Suphat Vongvisessomjai |
| Examination Committee(s) | Imamura, Fumihiko ; Sutat Weesakul
|
| Scholarship Donor(s) | Royal Thai Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1994 |