中文摘要：

复杂边界，尤其是发生干湿变化的动边界，一直是二维水沙数学模型计算的难点，也是控制计算收敛和精度的关键。本文主要介绍在二维浅水方程和泥沙数学模型中采用斜对角笛卡尔方法结合干湿边界点的变化来处理复杂边界问题，并将这一方法应用到北京首都国际机场扩建工程跑道高程设计和华能丹东电厂海水蓄水库泥沙淤积的模型计算中。计算表明，该方法拟合精细、处理简单、计算高效，与实测结果吻合较好。

英文摘要：

Complex boundary, especially the wet-dry dynamic boundary, is a challenge problem in the calculation of two-dimensional flow and suspended sediment transport. It also holds the key point of dominating the calculation convergence and precision. This paper presents the Diagonal Cartesian Method to approximate the boundaries in two-dimensional shallow-water and sediment transport numerical simulation, together with the wet-dry variation of boundary points. This method is applied to the computations of the runway elevation of Beijing Capital International Airport and the sediment deposition in seawater impoundingreservoir of Dan-dong electric power plant. It is shown that this method takes the advantages such as high precise simulation, simple grid generation and short CPU time.