山区河流河床结构对推移质输沙率的影响

河床结构是山区河流河床在洪水过程中达到较强阻力及较高河床稳定性时床面大颗粒的组合，对山区河流的推移质输沙起重要影响．引入河床结构强度S对山区河流河床结构进行定量化研究，使用河床结构测量设备对河床强度进行测量，采用类似于坑测法的子母双槽进行推移质输沙率实测，对云南小江流域的15条主要支流河床结构及推移质输沙进行野外实测，发现推移质输沙强度至少受单宽水流能量与河床结构发育程度共同影响，在同等级水流能量条件下，河床结构的发育程度越高的河流（或河段）其推移质输沙强度越小，河床强度值越小的河流（或河段）推移质输沙强度越大．单宽水流能量小于50kg／（m·S）、河床结构强度大于0.35时，推移质输沙率接近零．

Effects of Riverbed Structure on Transport Rate of Bed Load in Mountain Streams

Riverbed structures, which affect bed load transportation in mountain streams, are structures of boulders and cobbles on mountain streambed rearranged by flood flow to reach high resistance and high bed stability. A parame- ter Sp was introduced to describe the intensity of a riverbed structure. A specially designed instrument was used to measure the riverbed structure intensity, and a double-box bed load sampler was used to measure the transport rate of bed load. Field measurements on the bed load transportation, riverbed structure and hydraulic features were conducted in 15 tributaries of Xiaojiang River in the upper Yangtze River Basin in China. It has been found that the transport rate of bed load is affected by both the unit stream power and riverbed structure. In rivers or reaches with a similar unit stream power, the higher the riverbed structure intensity （the bigger the Sp）, the lower the transport intensity of bed load, while the smaller the Sp, the higher the transport intensity of bed load. When the unit stream power is less than 50 kg/（m·s） and Sp larger than 0.35, the transport rate of bed load would be 0.