The fractal characteristic change in the Huanghe River Estuary due to the hydrodynamic conditions' variation

摘要

The study area lies in the subaqueous delta, which came into being in 1964～976. One oil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynamic conditions on the north side of the road are relatively violent, on the contrary the hydrodynamic conditions on the south side of the road are nearly placid. This makes the study area a natural laboratory for studying the influence of the hydrodynamic conditions on the fractal characteristics of the tidal flat. Selecting an area is named Case Ⅰ on the side of stronger hydrodynamic activities and an area is named Case Ⅱ on the other side. Measuring the topography and sampling and analyzing the granulometrical composition, it is found that the hydrodynamic conditions have fatal influence on the surface fractal dimensions and the granulometrical fractal dimensions of the area. In Case Ⅰ , which has strong hydrodynamic conditions, the surface fractal dimensions are obviously larger than those of Case Ⅱ , and the granulometrical fractal dimensions are relatively smaller than those of Case Ⅱ , the surface fractal dimensions of Case Ⅰ decrease quickly with the increase of grid size; the granulometrical fractal dimensions are disperse, while the hydrodynamic conditions of Case Ⅱ are just reverse. A sampling line and a core sampling on each side of the road are selected. It is found that on the south side of the road the granulometrical fractal dimensions vary regularly in the line and with the depth, the farther apart from the road, the smaller the fractal dimensions, and the deeper the sampling position the larger the fractal dimensions, while granulometrical fractal dimensions on the north side of the road have no such regularity pattern. The mechanism of the influence of the hydrodynamic conditions on the fractal characteristics is discussed.