Channel deformation process of a gravel-bed river with vegetation zone was investigated in the present study. The channel is assumed to be constituted by gravel-silt mixture. When we simulate this deformation process, the evaluation of erosion rate of silt from gravel-bed is important. The formula by Ashida and Fujita  is only the applicable one. In this study, a “gravel-silt-packed bed model” was newly invented and introduced in order to make the computation effectively with the above mentioned formula. The model enables us to predict a temporal variation of sediment composition in bed as well as the bed elevation reasonably. In this paper, the model was applied to investigate the effect of both a zone of vegetation and a silt erosion and deposition on the channel deformation. As a result, it was confirmed that a depositional terrace like landform formed just inside the vegetation zone around a water margin, which was observed and reported by Fujita et al. .
An experimental field survey was conducted at the Gentaro sabo dam to evaluate the basic characteristics of a geophone placed on the spillway of the Hira River. A geophone is a device used to measure sediment discharge by picking up sounds of sediment particles that hit steel pipes located in a riverbed. This study analyzed kinetic energy and sediment discharge in relation to acoustic energy, i.e., voltage data recorded and sensitivity of detection. Results of this study showed that 1) data exceeding one particle's kinetic energy of 30 × 10-9 kg m2/sec2 ( a 2.0-mm particle or larger) should be selected when acoustic energy is analyzed; 2) a high correlation between acoustic energy and sediment discharge shows that sediment discharge can be analyzed from acoustic energy; and 3) the sensitivity of detection can be analyzed when the size of particles hitting the geophone and water depth are known.