二维贴体坐标系下的非均质河床组成空间插值

Spatial interpolation of bed material data in boundary fit curvilinear coordinate system in river channel

弯曲不规则河道的床沙组成在空间上具有一定分布规律,但主要体现在水流方向和河宽方向,地理坐标系内地统计学插值方法难以应用,针对该问题提出采用贴体坐标变换技术与地统计学原理相结合的方法对河床组成实施空间插值。结合实例河段的计算表明,在贴体曲线坐标系内实施空间变异函数分析,能够有效识别床沙组成的空间分布规律,从而满足Kriging法插值的前提条件。相比于传统插值方法,该方法的计算结果更能反映床沙组成分布各向异性、滩槽等不同位置沙层厚度差异明显的特点,从而可为河道变形的数学和物理模型边界条件的确定提供支撑。

In a curved river channel with irregular bank boundary,the law of spatial variation of bed material is often apparent only in the streamwide direction and the transversal direction. In such circumstances,it is difficult to apply geological statistical method to interpolate bed material structure inside the channel bed area within geographic coordinate systems. To overcome this difficulty,an algorithm integrating the coordinate transformation technology of boundary fit curvilinear and the theory of geological statistic was proposed. With the application example in a typical channel reach in the middle Yangtze River,it was exhibited that the pattern of spatial distribution of bed material layers could be distinguished effectively when analyzing spatial variation function in boundary fit curvilinear coordinates. Therefore,the precondition of the application of ordinary Kriging interpolation algorithm could be met. Comparing to conventional method of spatial interpolation,the calculation results achieved by this algorithm agree better with the characteristics of sand layer on bed,such as uneven distribution and variation anisotropy. The improvement of spatial interpolation of bed material structure with the proposed method will be helpful to the modeling of bed deformation in river reach of sand-gravel-mixing bed.