This study intended to use mathematical model to formulate dynamic equilibrium bay and derive C coefficients for parabolic bay shape equation, in order to use the model generated C coefficients to improve Tasaduak's (2014b) proposed equation which used data from experiment and real bays in Thailand. MIKE-21 sand transport module was the selected model to simulated the equilibrium bay shape. Once equilibrium bays were created, C coefficients can be extracted. The dynamic equilibrium bay was created and tested the equilibrium state. By the morphological analysis, the simulated bays have stable shorelines after 3 morphological years but there were still observable changes in bed level. By investigating longshore sediment transport, the simulations had just only generated close-to-equilibrium bays as the longshore sediment transport in shadow zone and normal zone did not show exactly equality. However, further study about dimension of the river impacting the morphological into bays is also need to be covered due to limitations of the model which cannot control the amount of sediment supply into bay. The developed C coefficients for dynamic equilibrium bay have been proposed and were derived mainly by the data obtained from hydraulic laboratory with artificial bays, the actual bay in Thailand and presented numerical model simulated bays. The newly proposed equations were better developed compared to Tasaduak{u2019}s (2014b) equations by showing less RMSE approximately by 0.02, 0.04 higher efficiency index and more R2 by 0.10. However, the developed equations still need to verify by the data from the actual bays in various regions of the world.

Thesis (M. Eng.) - Asian Institute of Technology, 2016