Run-off process of suspended sediment in mountain rivers

1.悬移质的径流与径流过程在高原河流域同步观测了悬移质浓度、流量和降雨强度，并讨论了它们之间的关系。结果发现了以下事项。悬移质浓度与降雨强度有很强的相关性，但由于坡面土壤的冲刷速度很快，两者之间的关系并不唯一。由于同样的原因，流量与悬移质浓度的关系也不是唯一的。今后应研究这种来源地区情况的变化。悬移质扩散理论根据以往的研究，一般采用的悬移质扩散方程在扩散系数较大的情况下，不能很好地解释大糙率陡槽中的悬移质浓度。我们已经提出了一个带有源项的扩散方程，并在上面显示了浓度-所述通道可以通过具有普通扩散系数的方程来表示。悬移质径流过程的数学模型在给定悬移质浓度边界条件的情况下，可以用本文提出的扩散理论来分析悬移质径流过程。但是，由于泥沙的产生过程过于复杂，边界条件不易确定。我们将进一步研究这一点。

1. Stream flows and runoff process of suspended sedimentWe observed suspended sediment concentration, flow discharge and rainfall intensity simultaneously in the Takahara river basin and discussed their relationship. As a result, the following matters were found out. Suspended load concentration is strongly dependent on rainfall intensity, but the relation between them is not unique because the soil on slopes is quickly washed out. The relation between flow discharge and suspended load concentration is not also unique because of the same reason. This change in the situation of source areas should be studied in future.2. Diffusion theory of suspended sedimentAccording to previous study, the diffusion equation of suspended sediment which is generally used cannot explain a suspended sediment concentration in a steep channel with a large roughness without the much larger diffusion coefficient In this paper, we have presented a diffusion equation with a source term and shown the concentration in the above-mentioned channel can be expressed by means of the equation with the ordinary diffusion coefficient.3. Modeling of runoff process of suspended sedimentIf the boundary condition of suspended load concentration is given, the runoff process of suspended sediment in river systems can be analyzed by means of the presented diffusion theory. However, the boundary condition can not be easily evaluated because the sediment production process is too complex. We will study more about this point.