An Experimental Geographic Information System for the Watershed Management of Mountain Streams.

流域管理就是要有计划地修建堤岸、防冲坝和河床调节器，以避免泥石流可能造成的人员和物质损失。为了制定这样的计划，必须估计河床上的沉积物数量，并了解它们运动的原因。沉积物主要来源于山坡和河岸的滑坡。因此，估算滑坡对河床的泥石流补给量是非常重要的。为此，我们必须建立一个滑坡可能性图，以估计泥石流的供应量。在此前提下，以山梨县境内的稻俣川最大支流稻俣谷为例，分析了影响滑坡的地形要素。植被，坡度， 关于我们 方位角、斜率形式（凸度和剖面）是最关键的要素。由于植被随着时间的推移而变化，无论是自然的还是人工的，因此没有列入制图要素。将坡度图、方位图和坡形图经彩色滚筒扫描仪数字化后叠加成滑坡易发性图。对各要素进行评分，根据总评分，首先将边坡单元划分为不稳定或稳定，然后根据概率将每个单元再划分为两类，共分为四类。（数字地形模型）计算坡度、方位角和高程，并将地形图数字化后生成河流图。我们还将现有的地质、植被和土壤图数字化。利用这些因子进行统计分析，提取出影响滑坡的地形要素。叠加数字这些元素，我们制作了该地区的滑坡易感性地图，包括不稳定（两个子类）和稳定（两个子类）类别。将该图与现有滑坡进行对比，发现约70%的滑坡属于不稳定滑坡。少

The watershed management is to make plans for constructing banks, erosion control dams, and stream-bed regulators so that human and material damages which may possibly be inflicted by debris flows can be averted. In order to make such plans, it is essential to estimate the amount of sediments on the stream bed and to understand the made of their movements. Sediments are mainly supplied from landsliding on the mountain slope and river banks. Consequently, it is very important to estimate the amount of debris supply to the stream bed from landsliding. For this purpose, we have to construct a landslide susceptibilty map, with which to estimate the amount of debris supply. In turn, we have to know the terrain elements which affect landsliding in order to map the landslide susceptibilty of mountain slopes.On this premise, we analyzed terrain elements affecting landsliding in Inamata Valley, the largest tributary of Amahata River, located in Yamanashi Prefecture. Vegetation, slope gradient, … More azimuth, slope froms (convexity and profiles) are among the most critical elements. Since vegetation changes with time, naturally and artificial, it was excluded from elements for the mapping. A landslide susceptibility map was constructed from superimposing maps of slope gradient, azimuth and slope forms which were digitized by a color drum scanner. The scores were assigned to each categories of elements and based on the total score, the slope unit was first classified as the unstable or the stable, each of which were further subdivided into two categories based on the probability, making a total of four categories.In the Omichi Valley of Tedori River, Ishikawa Prefecture, we utilized DTM (Digital Terrain Model) to compute slope gradient, azimuth, and elevation, We also constructed a stream map from topographic maps, which was subsequetly digitized. We also digitized the existing geologic, vegetation and soil maps. Using these factors, we run a statistical analysis and extracted the terrain elements affecting landsliding. Superimposing digitally these elements, we produced a landslide susceptibility map of the area, comprising of the unstable (two subcategories) and the stable (two subcategories) categories. Checking this map with the existing landslides, it was found that about 70% of the landslide fell into the category of the unstable. Less