A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1989

An analytical model is developed to predict the distribution of freshwater discharge from the main river into branches and to investigate the dimensionless damping modulus when tide propagates into the river. These information are required to calculate the salinity intrusion in estuary. In analytical model, the governing equations are solved using the approximation method of Perturbation to investigate the interaction of tide and freshwater discharge of Bassac River. The friction term is linearized according to IPPEN. The convective term and the effect of non-prismatic channel are also included. The zeroth order solution is obtained by direct integration. The IPPEN's solution is adopted for the first order solution, then the relations of dimensionless parameters of tide damping modulus are established. From the zeroth order solution and assumption of force balance at node, division of freshwater discharge for branches in looped branch can be determined from properties of channel and flow. The analytical model is found quite well in describing the freshwater division of Bassac river.