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Study on the Relationship Between the Fractal Characteristics of Rill Patterns on the Soil Surface and the Rate of Run-off Sediment

土表细沟分形特征与径流含沙率关系的研究

基本信息

批准号：
63460214
负责人：
FUJIWARA Teruo
金额：
$ 3.33万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

It is not too much to say that the best method to prevent soil erosion is to control the occurrence and the development of rill networks on the soil surface. Realizing this point, the purpose of this study is to investigate the relationship between the rill patterns and soil run-off, and, if possible, to know the method to estimate the soil loss from the rills.As rill networks have a irregular and complex patterns, it is difficult to express the patterns numerically by the classic geometrical concepts. In this study, the relationship between the soil loss and fractal dimensions of rill patterns was discussed by using the new concept of fractal geometrics i. e. fractal dimensions.First, we observed photograhically rill networks that develop on the bare slopes, and confirmed that they have a properties of fractal. And the relation between the fractal dimensions and entropy which can be obtained from power spectrum was discussed. On the other hand, the seasonable change of configuration of soil surface and the soil run-off have been also observed over three years on the test plots.Experiments were carried out by supplying artificial rainfall on the slope. In this experiment, the time variations of soil run-off were measured, and the relationship between the fractal dimensions of rill patterns and soil loss was discussed.The fractal dimensions of rill patterns that develop on-the-spot slopes which was composed of the four different soil were obtained. These soil are decomposite granite soil "Masado", "Kuroboku", weathered tuff and volcanic cohesive soil.The process of formation of rill patterns was simulated with the aid of a random pattern model, which is used in the fields of fractal geometry. As a results of the simulation, the simulated patterns were very similar to the rill patterns that develop on-the-spot slopes.

毫不夸张地说，防止土壤侵蚀的最佳方法是控制土壤表面细沟网络的发生和发展。鉴于此，本研究的目的是探讨细沟形态与土壤径流的关系，并在可能的情况下，了解细沟侵蚀量的估算方法。应用分形几何的新概念，探讨了土壤侵蚀与细沟形态分形维数的关系。e.首先，我们对裸露坡面上发育的细沟网络进行了摄影观测，证实了细沟网络具有分形特征。并讨论了分形维数与熵的关系。另外，在坡面人工增雨试验中，还观测了三年来坡面土壤表面形态和径流的季节性变化。通过对坡面土壤径流时间变化的测定，探讨了细沟形态分形维数与土壤流失量的关系，获得了4种不同土壤组成的坡面细沟形态的分形维数。本文采用分形几何学中的随机模式模型，模拟了细沟模式的形成过程。作为模拟的结果，模拟的模式是非常相似的细沟模式，开发现场斜坡。