在灌溉网渠道设计工作中采用图解法来简化计算,以节约时间和人力,在我国目前技术力量缺乏的情况下,大力进行兴修水利和改善灌溉系统的工作中,是有很大意义的。过去很多书籍都介绍过关于渠道图解的方法,但因为限于渠道糙率 n 及边坡系数 m,要绘制很多图表,才能适合各种不同 n 及 m 时的情况。现仅介绍一种渠道最有效水力断面简易曲线图(见附图),只要绘制不同边坡系数的一组曲线、而用一个系数来解决不同糙率 n 时的流速系数 C 值的变化,这样就可避免绘制大量曲线的麻烦,而实用上精确度也可以达到要求,现将绘制曲线图所根据的原理公式及应用步骤分别简单介绍如后:1.绘制曲线图所依据的公式及改正系数 C_n 的推求曲线图系假定糙率 n=0.025,依据最有效渠(?)水力断面公式求出不同边坡 m 时的流量率绘制而成,即 In the irrigation network channel design work using graphic method to simplify the calculation in order to save time and manpower, in our country’s current lack of technical strength, vigorously carry out water conservancy and improve the irrigation system work, is of great significance. Many books in the past have introduced methods of channel plotting, but because of the limited channel roughness n and slope factor m, many charts have to be drawn in order to be suitable for a variety of different n and m situations. Now only introduce a simple curve of the most effective hydraulic section of the channel (see attached map), as long as a series of curves of different slope coefficients are plotted, and a coefficient is used to solve the variation of the coefficient of flow rate C at different roughness n, You can avoid the pain of drawing a large number of curves, and practical accuracy can meet the requirements, the graph is based on the principle formula and application steps are briefly described as follows: 1. Draw the graph based on the formula and the correction factor The deduced plot of C_n is based on the assumption that the roughness, n = 0.025, is calculated from the flow rate of different slopes m according to the formula of hydraulic section of the most effective canal (?), That is,