上海崇明东滩岸线演变分析及趋势预测

认识崇明东滩岸线的演变规律，对于崇明东滩湿地的保护和利用具有重要意义。利用面向对象的方法，选取1987年至2006年中的6景Landsat-5 TM卫星影像数据，解译出对应年份的东滩岸线。为了对较复杂的非平直岸线的变化进行建模，提出了基于地形梯度的正交断面方法，构建了基于图形学的分析预测模型，对岸线的演变进行分析，预测了2010年和2015年的岸线位置。结果显示：（1）崇明东滩以东南角节点为界，分为南侧的侵蚀岸段和其余的淤涨岸段，总体淤涨速率有减慢趋势，最大侵蚀速率为22.0 m/a，最大淤涨速率为247.2 m/a；（2）北侧自东旺沙水闸向东约4 km长的岸段存在明显的冲淤交替现象；（3）岸线演变受抑制区段都位于东滩两侧岛影缓流区的边界；（4）由于岸外东南侧发育有10 m深槽，除非有特殊的水动力条件出现，东滩未来的岸线将偏向东北方向演变。

Analysis and Trend Prediction of Shoreline Evolution in Chongming Dongtan, Shanghai

Understanding Dongtan shoreline evolution has important significance for Dongtan wetland conservation and utilization. Based on object-oriented method, the shorelines of Dongtan are extracted from 6 scenes of Landsat-TM satellite images from 1987, 1990, 1995, 1998, 2003, and 2006, respectively. To model the shoreline changes, the authors developed an orthogonal-transect method, with which a series of transect is formed at a regular interval along 1987 shoreline and each transect goes along the direction parallel to the topographic gradient. The transect is then modeled with a graphics based fitting method and the shoreline dynamics are then analyzed. In addition, the spatial position of shorelines in 2010 and 2015 are also predicted. The results indicate that the shorelines of Dongtan are divided into the eroding segment in the south and accreting segment in the east and north. The eroding shoreline segments basically maintain unaltered and the accreting shoreline segments continue to expand by gradually decreasing speed. The maximum erosion rate and the maximum accretion rate are respectively 22.0 m/a and 247.2 m/a. The “suppressed” shoreline segments lie in the region of the boundaries of the island shadow. The future shoreline would evolve northeastwards to fit the 10 m isobaths unless the exceptive hydrodynamic conditions occur.