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20世纪六七十年代,在世界各地普遍进行小流域水土流失规律的研究。日本学者对此也作了大量的调查研究。其结论是:降雨过程中雨水大部分渗入地下,只有当整个土层达到饱和时,才会发生冲积型径流。荒废山地径流泥沙输出是施工工地或林地的4倍。森林土壤饱和透水系数>100mm/h;饱和地面径流只发生在溪流周围的缓坡上,对林地没有侵蚀作用;在林地发生侵蚀是在雨滴击溅下被剥离,然后发生搬运的结果。雨滴击溅土壤而形成土壤结皮,渗透能力明显降低,侵蚀程度降低。在降雨量多和降雨强度大时,易发生泥沙灾害。当土层中有连续的大孔隙存在时,形成管流,其流量约占坡面上饱和侧向渗流量的90%;占坡面动力流的1/2;流速与地面的流速相等;管流对地下有侵蚀作用。溃散发生比降雨最大时刻晚约7h;径流发生比降雨晚约3h;以岩石为基体的径流从土层中流出时刻几乎同时发生。
In the 1960s and 1970s, the laws of soil and water loss in small watersheds were widely studied all over the world. Japanese scholars also made a lot of research on this. The conclusion is that most of the rainwater infiltrates into the ground during rainfall, and alluvial runoff occurs only when the whole soil reaches saturation. Deserted runoff sediment output is four times the construction site or woodland. Saturated soil water permeability coefficient of forest> 100mm / h; saturated surface runoff occurs only on the gentle slope around the stream, no erosion on the forest land; erosion occurred in the forest was stripped under raindrops, and then the result of handling. Raindrops hit the soil splashing to form soil crusts, significantly reducing the infiltration capacity and reducing the degree of erosion. In the rainfall and rainfall intensity, prone to sediment disaster. When there are continuous macropores in the soil layer, the tube flow is formed, which accounts for about 90% of the saturated lateral flow on the slope surface; 1/2 of the flow surface on the slope surface; the flow velocity is equal to the flow velocity on the ground surface; the tube Streams have an erosive effect on the ground. Collapsing occurred about 7h later than the maximum rainfall; runoff occurred about 3h later than rainfall; and the rock-based runoff occurred almost simultaneously at the same time.