中国科学院遥感与数字地球研究所-高光谱遥感应用技术研究室

【作者】              张旭凯                                                                                                                                           

【导师】              张霞

【 学位年度 】    2013

【论文级别】      硕士    

【关键词】          遥感；海岸线提取；海岸类型；潮位校正；精度验证 

【Key words】    remote sensing technology; coastline extraction; coastal type; tidal correction; accuracy verification

【中文摘要】

海岸线位置的确定对海岸带综合管理具有重要意义，利用遥感技术进行海岸线提取受到越来越多的关注。目前海岸线遥感提取主要存在两方面问题：1）海岸的类型有很多种，不同类型的海岸具有不同的地物特征，单一算法无法保证海岸线提取精度。2）由于受潮汐等因素的影响，从遥感图像上直接提取的水陆交界线并不是真正意义上的海岸线，要想获取真正的海岸线，需要将水边线进行潮位校正至平均大潮高潮线。

本文针对现有研究多为利用遥感图像进行瞬时水边线提取、缺少潮位校正和精度验证的问题，提出一种结合海岸类型和潮位校正的海岸线遥感提取方法。以秦皇岛市的海岸为例，结合海岸类型对高分辨率SPOT-4和SPOT-5卫星图像进行瞬时水边线提取，提取方法包括最小噪声分离（MNF）变换、改进的归一化差异水体指数（MNDWI）、数学形态学方法和改进的Canny边缘检测方法。

在精确提取瞬时水边线的基础上，分别采用基于验潮站数据和结合DEM数据的方法对水边线进行潮位校正。利用同时期海岸线现场GPS测量数据对提取的海岸线进行精度验证。GPS测量点到校正后岸线的距离平均值分别为3.48m和6.82m，比未校正的9.54m小，校正后的岸线提取精度比未校正高。基于验潮站数据的方法校正后岸线精度最高，82%的GPS测量点到该方法校正后岸线的距离小于5 m（1/2个像素）。

最后，基于本文方法提取的多时相海岸线数据，对秦皇岛市北戴河砂质海岸进行岸线变化分析。2006年至2009年间，区域内海岸线共向陆地方向移动3.30m，；2009年至2011年间，区域内海岸线共向海洋方向移动3.02m。

【Abstract】

The determination of the coastline position is of great significance to integrated coastal zone management，and the use of remote sensing technology to extract coastline attracts more and more attention. Recently, two problems which need to be solved when using remote sensing to extract coastline are as follows: 1) The accuracy of coastline extraction cannot be guaranteed by applying single algorithm，because there are many coastal types and different types of coasts consist of different characters. 2) Due to the influence of tide and other factors, the boundary of land and water, extracted from remote sensing image directly, is not the real coastline. To obtain the real coastline, tidal correction is needed to move instantaneous waterline to MHWS (Mean High Water Springs)

The existing researches are mostly focused on the extraction of instantaneous waterline，but lacking of tidal correction and verification of accuracy. This paper presented a method combining coastline extraction with coastal type and tidal correction. MNF rotation，MNDWI，morphology and edge detectionwere applied to SPOT-4 and SPOT-5 data acquired in Qinhuangdao coastal zone to extract instantaneous waterline.

Based on the accurate extraction of the instantaneous water line, this paper also adopted the methods of using tidal data, and DEM data to calculate the slope of shoal, respectively. Moreover, the verification of accuracy of coastline extraction was achieved by the GPS data obtained in the same period. The results show that the accuracy of coastline extraction using two methods is better than the uncorrected, as a result of comparing the mean distance between GPS point and coastline extracted. The mean distance by using tidal data and DEM data is 3.48m and 6.82m respectively, which is shorter than that without tidal correction, 9.54m. Besides, the distance between the coastline extracted by using tidal data and eighty two percent of GPS points is shorter than 5m (half of a pixel), making this method more accurate.

 Finally, this paper analyzed the coastline change by using multi-temporal sandy coastline data of Beidaihe which was extracted by this paper’s method. The results show that the distance of coastline moving landward is 3.30mduring the period of 2006-2009, and the distance of coastline moving seaward is 3.02m during the period of 2009-2011.