Mahunnop Bunpapong creator Suphat Vo.ngvisessomjai Chairperson Tawatchai Tingsanchali Examination Committee Overbeek, Henk Jen Examination Committee The Government of Canada Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1978 continuing eng 117 p. The longitudinal dispersion coefficient in inland waterway was calculated using experimental data from various.natural streams. It was found that the predictive equation proposed by LIN (1977) gave results with high degree of consistency and more convenience to apply. Moreover, when applying these data to the equation in the form proposed by HARLEMAN (1964), the results indicated that the equation in this form should be D x 119 R0 · 98. For longitudinal dispersion, in the zone of salinity intrusion in estuary, the relationship between various forms of dimensionless dispersion coefficient and Densiometric Estuary number were investigated. It turned out to be that no functional relationship can be drawn from these attempts. Therefore, the relationship between dimensionless dispersion parameter and Densiometric Estuary number, proposed by THATCHER and HARLEMAN (.1972). , were than tested using data from 5 estuaries. Instead of using the maximum tidal velocity and length of salinity intrusion were used to normalize the dispersion parameter. The equation describing this relation ship was found to be K/UfLi = 0.084 ED 0·32 Thereafter, the horizontal diffusion coefficients at Ao Phai, in the Gulf of Thailand, were calculated from the equation proposed by TAYLOR (1921) which had been transformed from Lagrangian to Eulerian system. The Lagrangian-Eulerian transformation factor, 8, was determined from experimental results of McQUIVEY, KEEFER, and SHIRAZ! (1971). It was found that the horizontal diffusion coefficients were in the order of 10 4 cm2 /sec (3-8 m2 /sec). The dimensionless diffusion coefficients in the ocean were found to be at the same order of magnitude as that proposed by Harleman (1964. The Reynolds number, was calculated by using the mean water depth as the characteristic length and the velocity was the average over half a tidal period of the maximum velocity of the whole period. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand Thesis (M.Eng.) - Asian Institute of Technology, 1978 Hydraulics Mathematics Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B22856 http://203.159.5.9/ait-thesis/detail.php?q=B22856 160398 20260818094000.0