Elucidation of the warning rainfall criteria against landslide disasters, taking the soil moisture content into consideration

在山区森林地区，道路或铁路和当地居民有时会遭受与洪水有关的泥沙灾害。在此基础上，开展了山区激流输沙径流监测和特征分析，建立了激流输沙径流判据和当地标准降雨预警和疏散。这项研究是在一个由古生代变质岩（主要是片岩）组成的激流上进行的，其植被主要由日本柏树组成，在墨西哥新莱昂、印度尼西亚苏拉威西、尼泊尔加德满都周围也有类似的森林斜坡。土壤深度平均约为50cm，渗透率为k=10^<-2> 10^<-3>阶。对降雨、风速、土壤含水率、输沙量（周期观测）进行监测，通过监测和3年以上的观测得到径流特征。1)基于平野流量理论或自组织临界假设（soc）的突发泥沙流量理论临界标准。根据现场观测，洪流（河岸区）沿线土壤含水量不受前期降雨的影响，洪流床或洪流边的泥沙径流也不受前期降雨的影响，其中不包括滑坡或边坡破坏引发的径流。根据现有数据，该方法的探测率或临界成功指数的准确性很高（几乎100%）。2)基于初等突变理论（ETC）的理论临界标准鉴于初等突变理论（ETC）可以应用于该临界线，则采用楔形突变理论用下式描述该临界线。但它有一个横轴交点，即Pd=0。雨是不可能取Pa和Pi的这种组合的。因此，ETC不适用于这种情况。由于现场观测所得的流床或流边泥沙径流量（不包括滑坡或坡面破坏引发的径流量）不受前期降雨的影响，因此本文推导的公式相对于其他方法更为简单方便。少

In mountainous forest areas, roads or railroads and local inhabitants sometime suffer from sediment related disasters along torrents. On this point of view, monitoring of the sediment runoff and analysis of its characteristic in a mountainous torrent have carried out, in order to set up the runoff criteria of sediment from the torrent and the local standard rainfall for warning and evacuation. The research is run on a torrent whose geology consists of Paleozoic metamorphic rocks (mainly schist) and whose vegetation consists of mainly Japanese cypress as well as in similar forest slopes in Nuevo Leon Mexico, Sulawesi Indonesia, around Kathmandu Nepal. Soil depth is approximately 50cm in average and permeability is k=10^<-2> 10^<-3> order. Rain, wind speed, soil moisture content, sediment discharge (periodical observation) were monitored and the sediment runoff characteristic obtained by the monitoring and the observation over 3 years.1) Theoretical Critical Standard of Sudden Sediment R … More unoff based on the Hirano's discharge theory or the Self Organized Criticality Assumption SOCThe soil moisture content along the torrent (riparian area) is not affected by antecedent rainfall according to the field observation, so is the sediment runoff from torrent bed or torrent sides which does not include the runoff triggered by landslides or slope failures.The accuracy of this method contemplated by detective ratio or critical success index with the present data is high (almost 100%).2) Theoretical Critical Standard based on the Elementary Catastrophe Theory (ETC)Providing that the Elementary Catastrophe Theory (ETC) can be applied to this critical line, the critical line is described by next equation adopting the wedge type catastrophe theory. However, it has the cross point with lateral axis i.e. Pd=0. It is impossible for rain to take this combination of the Pa and Pi. Therefore, the ETC is not suitable in this case.Since the sediment runoff from torrent bed or torrent sides (which does not include the runoff triggered by landslides or slope failures) is not affected by antecedent rainfall based on the field observation, formulas derived in this study is rather simple and handy than the other methods. Less