杭州湾海岸线信息的遥感提取及其变迁分析

Coastline Mapping and Change Detection along Hangzhou Bay Using Remotely Sensed Imagery

综合利用ISODATA分类、地图综合、离散地物去除和岸线追踪等技术,通过ENVI和ArcGIS实现了海岸线遥感信息的提取。以1979、1987、2000和2005年4期Landsat影像为基础数据,提取了杭州湾海岸线;将提取的目标海岸线重采样为30~960m等10种空间分辨率,从而计算分维数并分析其变迁。研究表明:1979~2005年杭州湾海岸线长度增加了近37.5km,其中北岸增加的长度(24.9km)大于南岸(12.5km);同时,杭州湾海岸线具有显著的分形特性,其中1979~1987年分维数增大,1987~2000年降低,而2000~2005年则为增大。宁波、绍兴、嘉兴、金山、奉贤和芦潮港6个重点海岸的岸线变迁表明,隶属上海市的海岸线受泥沙淤积、港口建设、沿海工业建筑和土地开发等的影响较大;而隶属浙江省的海岸线受自然条件、近海水产养殖和滩涂围垦等的影响较大。

Based on the integrated methods of ISODATA classification,map generalization,discrete surface features removal and shoreline tracking,this paper implemented the shoreline extraction by ENVI and ArcGIS.With four Landsat images acquired in 1979,1987,2000 and 2005,the shorelines along Hangzhou Bay were extracted.In addition,the shorelines were resampled to 10 levels at different spatial resolution from30 to 960m,and the fractal dimensions of shorelines and its variation were computed.Six selected coastal areas witnessed drastic shorelines changes were analyzed.The results demonstrated that the shoreline length of Hangzhou Bay has increased by 37.5km from 1979 to 2005.Amongst the shoreline changes along Hangzhou Bay(includes both North and South Shores),the increases along North Shore(24.9km)were larger than that of South Shore(12.5km).The goodness-of-fits shows that there is a strong feature for shoreline of Hangzhou Bay,and the fractal dimension increased both from 1979 to 1987and from 2000to2005,but it decreased from 1987 to 2000.An analysis of the six selected coastal areas,i.e.Ningbo,Shaoxing,Jiaxing,Jinshan,Fengxian and Luchaogang,illustrated that the shorelines of Jinshan,Fengxian and Luchaogang were mainly affected by the sediment deposition,harbor construction,coastal industrial constructions and land reclamation,whereas the shorelines of Ningbo,Shaoxing and Jiaxing were mainly affected by natural conditions,offshore aquaculture and intertidal zone reclamation.