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近年来。在多泥沙河流上引水的一些灌区,用混凝土衬砌的渠道杂质及泥沙淤积,使过水断面减小,糙率相应增大,输水能力骤降。管理单位每年投入大量的人力和资金进行清淤,但效果甚微,成为管理上的一大难题。泥沙杂质沉积渠道,改变了原来混凝土渠槽的边界条件。直观上是设计过水断面的减小。但往往泥砂、垃圾、砖石等杂质在渠床上沉积厚度并不大,阻水影响也不明显,但却使渠床糙率改变,这种糙率改变对衬砌渠道的过流影响相当惊人。
In recent years. In some irrigated areas where diversions take place on the multi-silt rivers, the channel impurities and sedimentation caused by the concrete lining reduce the cross-section of the water and the roughness increases correspondingly, and the water delivery capacity plunges. The management unit invests a lot of manpower and funds every year for dredging, but with little effect, it becomes a major management problem. Sediment sediment deposition channels, changing the original concrete trench conditions. Intuitively designed to reduce the cross-section of the water. However, sediment, trash, masonry and other impurities are often not deposited on the canal bed thickness, water blocking effect is not obvious, but the channel roughness changes, which changes in the roughness of the lining channel overcurrent quite alarming.