【摘要】 计算历史时期海岸线变化率常用的数学方法有端点法、平均速率法、线性回归法和折剪法。对于线性均变海岸,这几种方法的计算结果之间差异很小,反映的岸线变化趋势比较一致,但对于振荡性或过渡性海岸,计算结果之间有较大的差异。端点法和平均速率法能较好地反映长期岸线变化的总趋势;线性回归法有助于反映海岸变化的过程和规律性;折剪法则可以发现并删除数据序列中的不稳定因素,减小这些异常值的影响。平均速率法在引入最小临界时间概念后,可以平滑突发事件对总计算结果的影响。若引入最小临界时间前后的计算结果有较大变化,则应引起对海岸变化过程中的短期事件的关注。对线性均变海岸,在实际工作中可以根据从简有效的原则选择计算方法,而振荡性和过渡性海岸则应综合使用各种计算方法,尽量以多元回归法取代线性回归法来反映岸线变化规律。计算中使用的数据总量和取样频度、总采样时间长度及数据的精度均会影响到计算结果的精度。以山东日照的2个岸段为例,分析了过去20a间岸线的长期观测资料。结果表明,影响2个岸段演化的因素和2个海滩的发育过程明显不同。第一岸段为典型的线性均变海岸,各数学方法计算结果基本一致,根据过去20a的资料计算得到的岸线变化率,可以作为未来岸线变化预测的依据。而第二岸段则?更多还原

【Abstract】 The commonly used methods for calculating the shoreline change rate based on the coastal evolution history include end point method, average the method, linear regression method and jackknife method. The calculated results applying these methods to the linearly changing coasts similar, but the obvious difference between the calculation results in applying to the oscillating or transitional coasts can be found. End point method and average rate method are useful for reflecting the general trend of longterm shoreline change, linear regression method is useful for reftecting the coastal change process and regularities, and jackknife method can be used to reduce the effect of anomalous data on the general shoreline change trend. The average rate method with minimum critical time can be used to smooth the effect of anomalous shortterm event on the general change frend and to eveluate the significance of those effects. In practice, the simple and effective calculational method can be chosen for the linearly changing coasts, while different calculational methods shall be used for the oscillationg or transitional coasts, and it is recommendated to use multivariate regression method rather than linear regression method for reflecting the shoreline variabilities. The factors affecting the calculated result accuraacy include total amount of data, sampling frequency, total sampling time length and data accuracy.In this paper, the shoreline data observed in past 20 years are analysed to study the shoreline change rate in two beach profiles along the coast of Rizhao, shandong Province. It is shown from the study resluts that the factors affecting the two coast section evolution and the two beach development processes are different from each other. The first coast section is typical linearly changing coast, and the calculated shoreline change rate can be used as the basis for predicting the future shoreline changes. The second coast sedion was greatly influenced by the human activities, the shoreline change rates calculated by different methods are significantly different from each other, and there are obvious short term oscillating events in the shoreline development process, so the calculated historical shoreline change retes can only be taken as the background data for predicting the future shoreline change trend, and further monitoring is needed for predizting the future shoreline change trend in the second coast section.更多还原