APROBABILISTIC PREDICTION MODEL ON SEDIMENT PRODUCTION IN MOUNTAIN REGION

重要的是要建立一个模型，描述通常或不寻常的泥沙产生过程的要点，以便准确地估计泥沙产生速率。在本研究中，以冻融产沙量为常态，边坡崩塌为非常态，提出了在模型中引入大气和水文变量的概率密度函数，从而提供产沙量概率特性的基本模型。首先，我们建立了裸露边坡的冻融过程模型。模型中考虑了气温、风速和太阳辐射作为参数，还可以考虑坡角和坡向。因此，该模型的优点是适用于世界上任何有大气、水文和地形资料的斜坡。通过观测数据与模拟结果的对比，验证了模型的有效性。田中和高原河流域。应研究风化基岩向土壤的转化过程，但该模型可作为全球变暖对产沙量影响的评价模型。其次，提出了考虑边坡内部土管的边坡破坏数值模型。利用该模型，讨论了土管和桩堵塞对边坡失稳发生的影响。此外，我们还研究了两种不同类型的斜坡，即主要受粘聚力或摩擦力作用的两种斜坡的破坏特征。前者发生含水率较大的长期崩塌，后者发生由短期崩塌组成的阶段性崩塌。

It is important to develop a model describing the essential points of usual or unusual sediment production process to estimate precisely the sediment production rate. In this research, taking up the sediment production due to freezing and thawing as a usual event and the slope failure as an unusual event, we have proposed the fundamental models that could provide the probabilistic properties of sediment production if the probability density functions of atmospheric and hydrological variables are introduced into the models. Firstly, we have developed a model for freezing and thawing process on bare slopes. Air temperature, wind velocity and solar radiation are included in the model as the parameters and also slope angle and direction can be considered. Therefore, an advantage of the model is applicable for any slopes in the world where the atmospheric, hydrological and topographical data are available. The validity of the model was verified by comparison between the observation data and the simulation result for Mt. Tanakami and the Takahara river basin. A transformation process from weathered bedrock to soil should be investigated, but this model could be developed as an evaluation model for the influence of the global warming on the sediment production. Secondly, we have proposed a numerical model on slope failure considering the soil pipes inside of slopes. Using the model, we discussed the influence of soil pipes and the piles clogging on the occurrence of slope failure. Also, we have investigated the characteristics of slope failure for two different types of slope, namely, two slopes sustained mainly by cohesion force or friction force. For the former, a long collapse with much water content occurs, and for the latter, a phased slope failure composed of short collapses take place.