河流泥沙水文学模型边界条件参数化方法探讨

针对河流泥沙水文学模型,在对基础方程(考虑上站来水含沙量的幂律函数公式)基本内涵(不平衡输沙理念、相对空间概念及自动调整作用)综合分析的基础上,从河道边界条件(河段长度、宽度、比降等)参数化角度出发,提出根据河道边界条件确定模型参数的方法。边界条件参数化方法途径主要包括:统计分析方法与理论比较途径。其中,统计分析方法宜先对同一河段选用同一进口断面,分别选取下游不同距离出口断面,通过实测资料统计回归,研究参数随距离的变化规律;理论比较途径主要基于对水文学、水动力学模型方程的理论比较分析,探求参数的计算方法。从断面质点系统跟踪角度来看,河流泥沙水文学与水动力学模型关于空间变化的基础方程,经过空—时变量变换均可表示为关于时间变化的滞后响应模型方程形式,两者区别在于对描述系统水沙组合的特征变量选择不同。河流泥沙水文学模型边界条件参数化最终结果转化为了水沙质点系统的调整时间与泥沙沉降时间,这从另一角度提供了对河流泥沙水文学模型方程物理意义的理解。

Analysis on the parameterization method boundary conditions of hydrological model for river sediment transport

For the hydrological model of river sediment transport which is expressed by the modified power law relationship between sediment concentration and flow discharge as well as an upstream sediment supply function, the boundary parameterization method was proposed from the perspective of the parameterization of river boundary conditions (length, width, gradient, etc.). This was accomplished based on the comprehensive analysis of basic connotation of hydrological model function, including non-equilibrium sediment transport, relative space and self-regulation concepts. The approaches on the boundary parameterization method include statistics method and theoretical comparison. In the statistics method, the river input section should be fixed first. Then the change rule of parameters with distance can be studied through the statistical regression of measured data for different output sections with different distances from the downstream. In the theoretical comparison,the hydrological and hydrodynamics models should be compared to deduce the change rule of parameters. Based on the cross-section particle tracing method, the hydrological and hydrodynamics model functions about space can be transformed into delayed response model function about time through variable transformation, and the difference between them lies in the different choice of characteristic variables. Finally, the results of boundary parameterization of hydrological model are transformed into adjustment time and sediment settling time of the water and sediment particle system. This provides an understanding of the physical significance of the hydrological model for river sediment transport from a different perspective.