Labyrinth weirs are often a favorable design option for regulating the water surface level in irrigation channels and increasing the spillway discharge capacity of dams. Sedimentation in irrigation channels and around related hydraulic structures such as weirs and turnouts is a common problem that causes disruption in operation. In this research, the effects of upstream sedimentation levels (non-sedimentation, S= 30, 60 and 90% of P=weirs’ height) and downstream bed levels on hydraulic performance of trapezoidal labyrinth weirs with various cycle’s geometries were investigated experimentally. The result showed that increase of S up to 60%P did not have a significant effect on the discharge coefficients and related total upstream head labyrinth weirs but further increase of S to 90%P reduced the discharge coefficient of weirs 15% approximately. Comparison of results indicated that for S up to 60%P, reduction of cycle number and its length in flow direction decreased the weirs’ discharge coefficients. However, by increasing S to 90%P, reduction of the apex angle of cycles and increase of the length of weirs in flow direction decreased the discharge coefficients of weirs. Analysis of results indicated that increase of tailwater level to two-thirds of P changed the flow pattern of falling nappe and the discharge coefficients of weirs changed significantly especially at high flow discharges. Finally, statistical equations were developed for estimation of the discharge coefficient of the trapezoidal labyrinth weirs for different upstream sedimentation levels and tailwater levels.

迷宫堰通常是调节灌溉渠道水位和增加大坝溢洪道排放能力的有利设计选择。灌溉渠道和相关水利结构（如堰和道岔）周围的沉积物是导致运营中断的常见问题。在这项研究中，通过实验研究了上游沉积水平（非沉积，S = 30、60 和 90% P = 堰高）和下游床位对具有各种循环几何形状的梯形迷宫堰水力性能的影响。结果表明，S增加高达 60% P对流量系数和相关的上游总水头迷宫堰没有显着影响，但进一步增加S至 90% P使堰的流量系数降低约 15%。结果比较表明，当S高达 60% P 时，减少循环次数及其在流动方向上的长度会降低堰的流量系数。然而，通过增加S到 90% P，循环顶角的减小和流向堰长度的增加降低了堰的流量系数。结果分析表明，尾水位增加到P的三分之二改变了落推布的流型，堰的流量系数发生了显着变化，尤其是在高流量时。最后，建立了统计方程，用于估算不同上游沉积水位和尾水位的梯形迷宫堰流量系数。