黄河三角洲海岸线分形研究

STUDY ON COASTAL FRACTAL OF YELLOW RIVER DELTA

海岸线分维数可以作为海岸类型划分、海岸演化过程和状态判别的量化参数。利用GIS方法和TM影像提取的黄河三角洲海岸线数据,计算较长时间序列上的黄河三角洲海岸总体岸段、淤积岸段、侵蚀岸段及人工岸段的海岸线分维数(D),并进行了三者分维数的方差分析。结果显示,淤积岸段平均海岸线分维数(D=1.080 7)大于侵蚀岸段的平均海岸线分维数(平均D=1.043 6)和人工岸段的平均海岸线分维数(D=1.057 6),总体岸段平均海岸线分维数为D=1.055 1;在95%信度水平上,三者具备统计意义上的显著差异性;在时间序列上,黄河三角洲总体海岸线分维数与侵蚀岸段海岸线分维数变化幅度较小,变化趋势基本一致,而淤积岸段海岸线分维数变化幅度较大,随着海岸工程的逐步完善,1989年之后人工岸段海岸线分维数趋于稳定。

Coastal fractal can be a quantitative factor to classification of coastal types, coastal evolvement, and status. This paper uses GIS and TM images to extract the Yellow river delta coastal data and calculates its fractal dimension （D） of the general coast, alluvial coast, erosion coast and man-made coast and gets their variance. The results indicate that the mean D value in alluvial coast （D = 1. 0807 ） is higher than the mean D value in erosion coast （D = 1. 0436 ） and than the mean D value in man-made coast （D = 1. 0551 ）. These three have an obvious variance statistically. In time sequence, the D values in the general coast and in erosion coast change a little with a similar trend, while the D value in the alluvial coast has a big variance. The D value in the man-made coast trends to be stable after the coastal projects were gradually improved since 1989.