漠阳江入海口海岸线分维及其机制分析

Analysis of fractal dimension mechanism in coastline of the Moyang River Estuary

分维数是反映海岸线复杂程度的客观依据。结合国内外海岸线分形研究进展,本文以漠阳江入海口附近海域为研究区,基于Landsat 8 OLI遥感影像对研究区域提取瞬时水边线,并利用潮汐数据进行校正得到海岸线;利用Fractal Fox2.0计算获得该海岸线的分维数为1.071;通过对研究区的分形机制分析,认为漠阳江附近的断裂构造对海岸起宏观控制作用,从而对海岸线的分维值也起了决定作用。根据断裂体系模型计算得到西侧海岸线的理论分维值为1.089,而对数螺线模型计算得到东侧海岸线的分维值为1.171;实际分维值相对理论值偏小,说明海岸带的沉积与侵蚀影响了分维值。此外,根据本区海岸侵蚀原因的分析,对分维机制进行了探究,初步论证的分维值大小可为海岸的冲淤变化研究提供参考。

Fractal dimension is an objective basis for reflecting the complexity of coastline. Combining the fractal research progress of domestic and overseas coastlines, this paper takes the coastline of estuary of the Moyang River as the study area, extracting the instant waterline based on the Landsat 8 OLI remote sensing image and corrected with tidal data to obtain the coastline. The value of fractal dimension is 1.071, which calculated by FractalFox2.0. Through the analysis of the fractal mechanism of the study area, it is found that the geological fault structure near the Moyang River plays a macro-control role on the coast. It also plays a decisive role on the fractal dimension of the coastline. According to the fracture system model, the western coastline theoretical fractal dimension is 1.089, and the fractal dimension of eastern coastline is 1.171 with the logarithmic spiral model. However, the actual fractal dimension is relatively small relative to the theoretical value, indicating the sedimentation and erosion of the coastal zone affect the size of the fractal dimension. This illustrates coastal sedimentation and erosion affect the fractal dimension of coastline. This paper also analyzes the causes of coastal erosion from coastal factors, sea level rise background, hydrodynamic effects (tides, waves, currents, storm surges, etc.) and human factors, so as to research the fractal dimension mechanism. The fractal dimension can provide an index and reference for the research on coastal erosion and deposition.