永定河典型生态护岸措施下坡面产流产沙试验研究

为实现永定河北京段沙质河道生态修复,通过野外径流小区放水冲刷试验,在3种放水流量(0.5,1.0,1.5 m~3/h)、坡度10°、5种护岸材料(生态袋、椰丝植生毯、三维土工网、松木桩、卵石)下分析不同生态护岸坡面的水动力学特性、产流产沙状况。结果表明:(1)3种放水流量下5种护岸材料布设坡面的平均流速均小于裸坡,5种护岸材料平均径流流速均表现为卵石松木桩三维土工网生态袋椰丝植生毯。5种生态护岸材料弗劳德数均小于1,雷诺数均小于500。(2)生态护岸措施有效减少产流,产流量随时间均呈对数显著增加,5种生态护岸材料平均径流拦截率表现为松木桩卵石三维土工网椰丝植生毯生态袋。(3)随放水流量的增大坡面产沙率增大,各生态护岸措施均能有效减少产沙量,各护岸措施的泥沙拦截效果随着放水流量增大显著降低。研究结果对永定河不同河段岸坡治理、生态护岸材料选择、永定河绿色廊道建设有重要意义,也对定量评价不同护岸材料下坡面的减水减沙效益提供参考。

Study on Runoff and Sediment Yield on the Slope with Typical Ecological Riverbank Protection Measures in the Yongding River

In order to realize the ecological restoration of sandy river course in Beijing section of Yongding River, through the field runoff plot drainage and scour test, the effects of different ecological riverbank protection measures on hydrodynamic characteristics, runoff and sediment yield during slope erosion process were studied. In the test, five kinds of bank protection materials (ecological bag, coir blanket, 3D-geomat, pine pile and pebble) were used, and the runoff and sediment yield of each treatment were analyzed under three kinds of water discharge flow rate (0.5, 1.0 and 1.5 m³/ h) and 10° slope. The results showed that: (1) Under the three release flows, the average runoff velocities of the five bank protection materials were all smaller than that of the bare slope, and the average runoff velocity of the five ecological bank protection materials followed the order of pebble > pine pile > 3D-geomat > ecological bag > coir blanket. The Froude numbers of the five ecological bank protection materials were all less than 1, and the Reynolds numbers were all less than 500. (2) Ecological riverbank protection measures could effectively intercept runoff and slow down the runoff production process, and the runoff production showed a significant logarithmic increase trend with time. The average runoff interception rate of the five ecological bank protection materials followed the order of ecological bag > coir blanket > 3D-geomat > pebble > pine pile. (3) The average sand production rate on the slope surface increased with the increasing of water discharge flow, and the ecological bank protection measures could effectively intercept the slope sand production, and the sediment interception effect of ecological bank protection material gradually decreased with the increasing of the water discharge flow. The research results were of great significance for the bank slope management of different sections of the Yongding River, the selection of ecological bank protection materials, and the construction of the green corridor of the Yongding River, and also provided a reference for the quantitative evaluation of the water and sediment reduction benefits of different bank protection materials.