This research aimed to ascertain the Manning roughness coefficient (n) and explore the impact of various factors on it across different phases and irrigation events. The Manning’s n for furrow irrigation was determined in the advance, storage, and whole irrigation phases utilizing the SIPAR_ID model, Manning equation, and WinSRFR software, respectively. Parameters affecting the Manning’ n were identified through Pearson and Kendall tests. The study involved measuring the Manning’s n under six distinct inflow rates, classified as low and high flows. Three irrigation events (first to third), advance and storage phases, two irrigation intervals, and two soil textures (Clay loam and Silty clay loam) were considered. Results indicated that the Manning’s n ranged from 0.017 to 0.636, 0.015 to 0.317, and 0.015 to 0.34 in the advance, storage, and whole irrigation phases during the first to third irrigation events, with mean values of 0.083, 0.054, and 0.055, respectively. Higher roughness coefficients were observed in the advance phase. Additionally, findings suggested that if the advance phase is short relative to the total irrigation time, the Manning’s n from the advance phase can be applied to the whole irrigation event without separate consideration for storage phase roughness. Pearson and Kendall statistical tests revealed that the Manning roughness coefficient during the entire irrigation event was strongly correlated with advance time (r = 0.65, p < 0.01) and moderately correlated with inflow and outflow rates, as well as initial soil moisture and cross-sectional flow area. A weak correlation was observed between the roughness coefficient and the furrow slope (r = 0.238). During the storage phase, advance time had the strongest positive correlation with roughness, while inflow rate had a weak negative correlation (r = −0.31).

本研究旨在确定曼宁粗糙度系数 （n），并探讨各种因素在不同阶段和灌溉事件中对其的影响。在前期、蓄水和整个灌溉阶段分别使用 SIPAR_ID 模型、Manning 方程和 WinSRFR 软件确定了沟灌的 Manning's n。影响 Manning' n 的参数通过 Pearson 和 Kendall 检验确定。该研究涉及在六种不同的流入率下测量曼宁的 n，分为低流量和高流量。考虑了三个灌溉事件（第一到第三）、前期和储存阶段、两个灌溉间隔和两种土壤质地（粘壤土和粉质粘壤土）。结果表明，在第一次到第三次灌溉期间，前期、蓄水和整个灌溉阶段的曼宁 n 范围为 0.017 至 0.636、0.015 至 0.317 和 0.015 至 0.34，平均值分别为 0.083 、 0.054 和 0.055。在提前阶段观察到较高的粗糙度系数。此外，研究结果表明，如果提前阶段相对于总灌溉时间较短，则提前阶段的 Manning's n 可以应用于整个灌溉事件，而无需单独考虑储存阶段的粗糙度。Pearson 和 Kendall 统计检验显示，整个灌溉过程中的 Manning 粗糙度系数与提前时间密切相关 （r = 0.65，p < 0.01 ），与流入和流出速率以及初始土壤水分和横截面积呈中等相关性。观察到粗糙度系数和沟槽坡度之间呈弱相关性 （r = 0.238）。 在储存阶段，提前时间与粗糙度呈最强的正相关，而流入率呈微弱的负相关 （r = −0.31）。