【作者】 何茂兵；

【导师】 吴健平；

【作者基本信息】 华东师范大学 ， 地图学与地理信息系统， 2008， 博士

【摘要】 九段沙湿地位于长江口北槽与南槽之间,是国家级湿地自然保护区,也是上海市重要的后备土地资源之一。然而,由于长江三峡工程等的影响,长江的输沙率和含沙量将下降到长江口前沿潮滩的冲淤转换临界值之下,加之海平面的加速上升,今后几十年长江口前沿潮滩将遭受侵蚀。因此,九段沙湿地的动态变化问题倍受人们关注。本文通过3S技术,即遥感(RS)、全球定位系统(GPS)和地理信息系统(GIS)技术,对九段沙湿地在近20a来的冲淤动态变化进行了研究,其主要内容和成果如下:1、对利用RTK-GPS在九段沙湿地的实测散点数据进行投影坐标转换、基于理论最低潮位基准的高程换算和数据质量检测等预处理,为构建数字高程模型(DEM)提供可靠的数据。2、针对RTK-GPS实测数据分布极其不规则的特点,分别采用普通Kriging插值法构建栅格DEM、采用带边界约束条件的Delaunay三角剖分方法构建TIN,精度分析结果表明:两者的精度相近,但从DEM的表面光滑性来看,普通Kriging方法要优于约束TIN方法。3、通过研究提取遥感水边线的最佳波段与九段沙涨落潮情的关系,总结出在涨潮中期提取水边线的最佳波段是短波红外波段,而在其他潮情条件下提取水边线的最佳波段是红色波段。4、针对九段沙潮间带遥感水边线空间跨度大而且明显起伏的特点,提出了通过遥感水边点宋获取潮间带高程的方法,与把水边线当作等高线宋处理的方法相比,更具合理性。5、针对数据源包括等高线、水边点(接近于等高线分布)及散点数据,而且数据分布又非常不均匀的特点,采用带多种约束条件的狄洛尼TIN来逼近九段沙湿地的实际地形,获得了较可靠的多时相DEM数据。6、依据多吋相DEM数据,分别从面积变化、水平方向的空间冲淤变化以及垂直方向的沉积速率等方面,讨论了九段沙湿地在近20a来的沖淤动态变化特征。7、为了客观评价湿地的稳定性问题,提出了年均冲淤活跃度的概念,即年均冲淤活跃度=100%×((淤积面积+冲刷面积)/起始面积)/相隔年数。更多还原

【Abstract】 Jiuduansha Wetland is located between the south and north troughs of Sand Bars in the Yangtze River estuary. It is one of national nature reserve and important land resource of Shanghai. However, because of the influence of the Three Gorges dam and other water conservancy projects and the accelerated sea level rise, it is likely the riverine sediment transport rate and the sediment concentration of the Yangtze River will decrease to less than the critical values in the coming decades to result in the tidal bank erosion in the Yangtze River estuary Foreland. So, the dynamic change of Jiuduansha wetland has attracted much attention.The dissertation has studied the dynamic erosion/sedimentation change of Jiuduansha wetland in the recent 20 years by 3S technology, i.e. remote sensing, global positioning system and geographic information system technology. The main contents and results as below:1. In order to obtain the reliable elevation data from the in situ measurement data by RTK-GPS in Jiuduansha wetland for DEM construction, the conversion relationship between geographic coordinate system and Shanghai local projected coordinate system is created, the elevation datum is converted to the theoretical depth datum, and the data quality is validated.2. To counter the problem of very irregular distribution of the in situ measurement data by RTK-GPS, the grid-DEM is generated by ordinary Kriging interpolation, and the TIN is generated by Delaunay triangulation with the boundary condition constraints. The results show that the two DEM precision are close, but ordinary Kriging interpolation is better than Delaunay triangulation in surface smoothing.3. By studying the relationship between the best band for waterline extraction and the tide condition, the conclusion is drawn that short wavelength infrared is the best band for waterline extraction in the middle of flood tide, and red band is the best band in the other tide condition.4. Aiming at Jiuduansha intertidal mudflat is so wide that the waterline is not horizontal completely and shouldn’t be simply assumed as a contour, the dissertation develops an elevation acquisition method by waterpoints, which is more reasonable than by waterline. 5. Aiming at the condition that the data source includes contours, waterpoints and scattered points, and the data distribution is very uneven, the Delaunay triangulation with several condition constraints is used to generate TINs, and multi-temporal DEMs are obtained.6. According to the multi-temporal DEMs, the dynamic change rules of Jiuduansha wetland are discussed in area change, horizontal erosion/sedimentation change and vertical sedimentation speed.7. A new parameter of annual erosion/sedimentation activity is defined in the dissertation to reasonably estimate the stability of Jiuduansha wetland.更多还原