Experimental Study on Resuspension, Transportation and Deposition Processes of Mud Particles on the bed of Estuaries

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Resuspension, transportation and deposition processes of mud particles on the bed of polluted estuaries yield two serious problems in hydrosphere. One is the turbid water as a result of the resuspension and transportation of mud particles themselves, and the other is the supply of nutrients and pollutant matters to hydrosphere. In this study, resuspension, transportation and deposition mechanisms of mud particles were investigated experimentally. The main purpose of this study was reasonably to estimate the critical shear stress of mud and the turbulent diffusion coefficient and trubulent fall velocity of suspended mud particles.Using visco-meters and an annular flume, the flow curve property and critical shear stress of mud were investigated experimentally. It was very interesting and important result that the critical shear stress of mud was determined approximately by its yield value.Convective dispersion mechanism of suspended mud particles in open channel shear flow was studied experimentally. The concentration of suspended solids were measured by the method of video-image data processing, and a laser doppler velocimetry was used in flow velocity measurement. It was found that the turbulent diffusion coefficient and fall velocity of suspended mud particles were closely related to the total energy of the low frequency components in vertical velocity fluctuation.Using the results obtained from the experimental studies, numerical simulations were executed to regenerate the tidal current velocity and turbidity of the Ariake sea. The fluid flow equation and mass transfer equation were formulated in forms that allowed the establishment of finite difference approximation of the two-dimensional single-layr model, and the numerical model was successfully coded.