宁夏红寺堡扬水工程增流改造应用了槽壳内衬SCL防渗膜，可有效减少工程投资、提高施工速度，但SCL防渗膜的降糙增流效果尚未验证。通过渡槽测流段面几何尺寸、水力坡降和多断面水力要素量测，按照明渠恒定非均匀流流态推算了工程改造前后渡槽糙率变化，分析SCL防渗膜降糙增流效果，为后续工程更新改造提供技术依据。结果表明：内衬SCL防渗膜，渡槽糙率可降低至0.011 5～0.012 0，较原有混凝土槽壳，糙率可降低0.001 17～0.001 82，降幅为8.86%～13.62%，渡槽过流能力可增加9.75%～14.99%。

In addition, the SCL impermeable film of the inner lining of the tank shell has been applied in the upgrading of the water project of Hongsipu in Ningxia, which can effectively reduce the project investment and increase the construction speed. However, the effect of SCL impermeable film on the reduction of flow has not yet been verified. Through the measurement of the geometric dimensions of the flow section, the hydraulic slope drop, and the multi-section hydraulic element measurement, the roughness rate of the aqueduct is calculated according to the constant non-uniform flow state of the open channel before and after the engineering transformation. The effect of SCL impermeable film on the reduction of flow is analyzed. Provide technical basis for the renewal and renovation of the follow-up project. The results showed that the roughness of the aqueduct can be reduced to 0.011 5~0.012 0 for the inner lining of the SCL impermeable film. Compared with the original concrete tank shell, the roughness can be reduced by 0.001 17~0.001 82, which can be reduced by 8.86%~13.62%. The overflow capacity of the aqueduct can be increased. 9.75%~14.99%.