1 AIT Asian Institute of Technology

Sand spit migration in a simulated river mouth

AuthorVithana, Hela Perakum Viduragomi
Call NumberAIT Thesis no.WM-97-12
Subject(s)Silt

NoteA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering
PublisherAsian Institute of Technology
Series StatementThesis ; no. WM-97-12
AbstractSiltation and sand bar formation in tidal inlets have been a serious hazard faced by many countries particularly, those having rivers with narrow inlets. The traditional engineering solutions such as construction of jetties have not been very successful due to their consequent erosion effects downcoast due to the discontinuity of longshore transport upcoast. The method of headland control as proposed by researchers like Silvester, Hsu et al., has found to reduce or completely cease longshore transport due to the formation of an equilibrium bay which orients the beach perpendicular to the wave orthogonals caused by the refraction and difraction effects .. The cases of (i ) River Only (ii) Wave Only (iii) Wave and River (iv) Wave and Headlands (v) Wave, River and Headlands have been simulated in a wave basin of 12m X 14m X 0.65m in the Hydraulic Laboratory using regular waves to understand the individual and combined effects of river flow, waves and headlands on the sedimentation of a river mouth. The other factors such as basic wave characteristics, river flow, water depth, beach slope, beach and river geometry have been maintained constant. Hydrodynamic behaviour in the vicinity of river mouth and the nearshore area has been studied by observing the movement of tracer dye and floats with respect to time. By the use of photographic data taken at the end of every two hour simulation time step the morphological change has been analysed. Morphology of all five cases were studied. Based on the experimental study the following conclusions could be reached : + After the insertion of upcoast headlands, the longshore transport velocity reduced remarkably after some time. The siltation near a simulated river mouth reduced accordingly when the longshore transpo1t ceases due to the formation of equilibrium bays. + The Albertson's (1948) classical equation for two dimensional turbulent jet is found to be applicable for predicting centreline velocity of a river flume with and without the effect of oblique waves. + The growth of a sand spit with the combined effect of oblique waves and river flow are found to follow a parabolic shape during the developmental stage.
Year1998
Corresponding Series Added EntryAsian Institute of Technology. Thesis ; no. WM-97-12
TypeThesis
SchoolSchool of Civil Engineering
DepartmentDepartment of Civil and Infrastucture Engineering (DCIE)
Academic Program/FoSWater Engineering and Management (WM)
Chairperson(s)Sutat Weesakul;
Examination Committee(s)Suphat Vongvisessomjai;Kazama, So;
Scholarship Donor(s)Asian Institute of Technology;
DegreeThesis (M.Eng.) - Asian Institute of Technology, 1998


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