RELATIONSHIP BETWEEN BOTTOM SHEAR STRESS AND TURBIDITY IN ESTUARIES

The formation of oxygen-poor water and the occurrence of hydrogen sulfide in estuary are caused by the sludge which contains a lot of organic substance. In order to examine measures against the water environment problems caused by the sludge, it is necessary to estimate bottom shear stress which is considered to be that exert influence on the behavior of bottom material. Based on our study, the bottom shear stress was estimated by the method of using the change of water level obtained by one-dimensional unsteady flow analysis and the density distribution obtained by field observation. The estimated bottom shear stress was validated by comparison with coefficient of eddy viscosity. In addition, the relationship between the bottom shear stress and the turbidity is discussed. The summary of the results is shown as follows; Increase in turbidity during flood tide is caused that the tip of saline wedge passes through a cross section; Due to increase in the velocity of toward downstream, the turbidity also increase during ebb tide.