一种基于断面高程数据的河道冲淤计算方法--曲线正交网格地形法

A Method for the Calculation of Erosion and Accumulation in the River Channel Using Bathymetric Data of River Cross Section:Based on Orthogonal-Curvilinear-Grid DEM

本文应用河道固定断面高程数据和卫星遥感资料,建立了一种基于曲线正交网格的河道数字高程模型(DEM),进而进行河道冲淤定量计算的普适方法。应用1991—2012年黄河孙口-艾山河段河道断面高程数据,结合卫星遥感资料,分别应用本文方法、断面法和基于矩形网格的网格地形法计算了孙口-艾山河段的冲淤演化,比较了不同方法的差异,探讨了不同方法产生误差的主要原因,结果表明:基于三种方法计算得出的研究区河道冲淤演化趋势基本一致,但冲淤量差异较大。断面法计算结果与本文方法结果较为接近,平均相对误差约为9%,其计算误差主要源于未考虑河道宽度变化和断面方位与河道夹角的变化。基于矩形网格建模计算结果与本文方法结果相差较大,平均相对误差可达40%以上,主要由于现有断面数据空间分布不均匀,导致计算网格对于弯曲河道的控制不足,进而导致河道高程插值失真。本文方法考虑了河道河势与河长变化,计算网格与河道边界拟合较好,优化了河道高程插值方法,降低了断面方位对插值结果的影响,能够准确的计算河道的冲淤通量。

A universal method based on a digital elevation model(DEM)is presentedin this paper to calculate the erosion-accumulation sediment volume in the river channel.The DEM is established based on the orthogonal curvilinear grid using bathymetrical data of cross sections and remote sensing data.To compare the calculating results with other methods,erosion-accumulation sediment volume in the river channel from Sunkou to Aishanin the lower Huanghe(Yellow River)is calculated using three methods,namely cross-section method,rectangular-grid DEM method and method in this study.The results indicate that the trends of the erosion-accumulation evolution calculated by the methods mentioned above are basically identical,but the amounts of erosion-accumulationsediment are quite different.The result based on cross-section method is very close to that based on this study with an average relative errorof approximately 9%.The error is mainly coming from the calculation model that does not consider the changes of river channel width and angles between bathymetrical cross sections and the river channel.The calculation result using rectangular-grid DEM method,however,has an over 40%average relative error compared with that using the method of this study.Such big erroris mostly caused by interpolation error of the river channel DEM due to uneven distribution of the cross section and poor fitting of DEM grid to the boundary of the river channel.The method in this study both fits better with river channel boundaryandreduces the error of interpolation,can calculatethe erosion-accumulation flux more accurately.