Calculation And Analysis Of Fractal In Microrelief At Artificial Digging

Water loss and soil erosion is one of the most serious ecological problems of China. Loess Plateau forms a surface structure of severe soil erosion, crossbar ravine and fragmentized field on account of its soil property, cultivated slope, concentrated precipitation and disrupted vegetation. Water erosion, as a main erosion type of Loess Plateau, which mainly happens in slope cropland, disrupts the local agricultural production severely.This study is a quantitative research of the transition of different erosion stages and the alteration of surface configuration in preliminary period. Based on the advancement of measurement modes and computing devices, the construction of microscopic water erosion model and the application of Fractal Theory, the study describes the initial process of water erosion and reveals the relation between the terrain and water erosion from a micro perspective, which offers a good foundation for the quantitative study of loess water erosion process in preliminary stage microscopically, and also provides a favorable reference for the simulation research of micro topographic surface runoff and sediment and substances transportation. Besides, it can deepen the understanding of water erosion development process and relevant mechanisms of the loess slopes and is beneficial to control soil and water loss.Indoor artificial simulation is adopted in the research, supplemented by an imitating chromatic, high-resolution(HR), interactive laser scanner(Topcon GLS-1500). The research is to acquire a cloud data of the micro topographic elevation point via its data collection, registration and denoising in different precipitation periods. Based on the data, a triangular irregular network, which is constructed by the combined application of GIS and Computer Technology, interpolates a high precision M-DEM. By ArcGIS and Java-based development platform Eclipse, the fractal dimension of the research areas can be calculated, and which will also testifies under microscopic scale water erosion in early stage has a good fractal property. The paper also reasonably explains the phenomenon of different erosion stages under different fractal dimensions, which lays the foundation of the micro-scale quantitative study of loess slope erosion development. The main contents and conclusions are as follows:Micro topography in the different early-erosion stages has a good fractal property. In this study, in the process of obtaining the fractal dimension, both the obtaining of the box dimension though micro topography drainage network extraction and the obtaining of the surface area dimension and the volume dimension have proved that each stage of water erosion has a good fractal property, has self-similarities on the form. Along with the water erosion stage develops different fractal dimensions can be achieved, which properly describe the different fractal property erosion stages. For example, with the development of the stages of splash erosion, surface erosion and gully erosion, the box dimension has transferred from 1.0025395 to 1.002194 and then to 1.0045762, showing that the fractal dimension can be used as indicators of micro topography erosion process.Fractal dimension provides a new way of thinking for the quantitative research and the distinction of different stages of water erosion. In the study of using the fractal dimension in different erosion stages, the surface area dimension and the volume dimension have captured the micro topographic surface area and volume are affected by the cutting-down gully brought by a channel development, so when the gully erosion dominates, it makes the fractal dimension changes significantly and the enlarging fractal dimension suddenly decreases. This offers a good research approach to qualitatively describe the gully erosion and a foundation for the fractal dimension to become an important parameter of micro topography erosion stage.In the modeling process of fractal dimension, the descriptions of different modeling fractal dimensions differ. As micro topography is for real, to reveal the water erosion law in the early stage via different modeling fractal dimensions has become possible. Through the drainage fractal dimension, it can be concluded that the basin topography is constantly developing and the construction of it is also strengthening. The fractal dimension implies the change in tectonic activity, namely the strengthening of the tectonic activity of the surface, which also implies the drainage fractal dimension is increasing; whereas the surface dimension and the volume dimension reveal the magnitude of erosion by the study of the filter loss in different stages. To conclude, the erosion regularity can be revealed from different angles by the fractal dimension built by different classification models.