Abstract Side weir is a hydraulic structure, which is used in irrigation systems to divert some water from main to side channel. It is installed at the entrance of the side channel to control and measure passing water into the side channel. Many studies provided side weir water surface profile and coefficient of discharge to measure water discharge diverted into the side channel. These studies dealt with different side weir shapes (rectangular, trapezoidal, triangular and circular), which were installed perpendicular to the flow direction. Recently, some studies dealt with skew side weir, but these studies still need to more investigation. Here we report to investigate oblique side weir theoretically using statistical method to supported other studies in this case. Measurement uncertainty discharge coefficient Cd was obtained by two methods: analytical according to the ‘Guide to the expression of uncertainty in measurement’ and the Monte Carlo method. The results indicate that all experimental results are consistent with the analytical results. The relative expanded uncertainty of the discharge coefficient Cd does not exceed 2%.

中文翻译：

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用蒙特卡罗法估算斜边堰流量系数的不确定性

摘要 侧堰是一种水工结构，用于灌溉系统中，将部分水从干渠分流至侧渠。它安装在侧通道的入口处，用于控制和测量进入侧通道的水。许多研究提供了侧堰水面剖面和流量系数来测量分流到侧槽中的水流量。这些研究涉及垂直于流动方向安装的不同侧堰形状（矩形、梯形、三角形和圆形）。最近，一些研究涉及斜边堰，但这些研究还需要更多的调查。在这里，我们报告使用统计方法从理论上调查斜边堰，以支持这种情况下的其他研究。测量不确定性流量系数 Cd 通过两种方法获得：根据“测量不确定度表达指南”和蒙特卡罗方法进行分析。结果表明，所有实验结果与分析结果一致。流量系数Cd的相对扩展不确定度不超过2%。