挟沙能力公式系数的最佳确定

Optimum approach to determine the coefficients in sediment-carrying capability formula

水流挟沙能力反映了运动水体所能挟带泥沙的最大能力,确定水流挟沙力公式对于泥沙数学模型的发展具有重要意义,而关键是其系数的最佳确定。基于最小二乘法原理,对目前广泛应用的水流挟沙力公式中的系数确定提出了一种新的方法———枚举法。枚举法直接应用最小二乘法,有别于常用的先取对数后再进行回归分析的传统方法,通过误差分析和结果比较,表明枚举法确定的系数更合理,也提高了公式的精度,使公式能更客观地反映水流挟带泥沙的实际能力。枚举法简单实用,是目前确定水流挟沙力公式系数的最佳方法。

The numerical model to simulate sediment transport and bed erosion or deposition in rivers, estuaries and coastal waters has become an important approach in sediment research. Because sediment transport is very complex and unstable, different mathematical models have been established based on different principles, such as viewpoints of sheer stress and energy of water flow. In China, the sediment-carrying capability formula based on the view of water flow energy equilibrium is widely applied in sediment numerical simulation to solve sediment problems in many important prajects such as the Three Gorge Project and the Regulation Project of the Deep Navigation Waterway in the Yangtze River Estuary. Sediment-carrying capability of water flow means the maximum capability of water flow to carry sediment. It is very important to obtain the sediment-carrying capability formula for developing sediment numerical models, and the key problem is to determine its coefficients in the best way. Based on the least square method directly, a new method called enumeration method is developed in this paper. This method is different from the normal method, which makes a regression analysis after logarithm. The error analysis and result comparison show the coefficients determined by the enumeration method are of more reasonability and that the results of the formula are more accurate in calculating the natural sediment-carrying capability of water flow. At present this method is simple and practical, thus it is the most optimum approach to determine the coefficients in the sediment-carrying capability formula.