水系连通机理及其影响因素

Mechanism and influence factors of water system connectivity

为了摸清水系连通性衰退的成因,本文通过引入水系连通性指标和推求河道水力几何关系,深入分析了水系连通性的连通机理和影响因素。结果表明河道纵向连通性取决于河道来水来沙条件与边界形态,侧向连通性取决于河道分汇流比及分汇流区的水流流态和冲淤形态,河道横向连通包括河道滩槽并存、洪水期滩槽水沙交换以及水生植物的传播,主要是通过洪水周期性的涨落来实现的;流域降水变化、河道整治与堤岸工程、水库枢纽建设和引水分流工程等因素是河道连通性的主要影响因素。总之,河道来水来沙条件、分(汇)流状况与河道边界形态等之间的协调是水系连通性的内在机制和控制关系。

In order to analyze the causes of water system connectivity decline,the connectivity mechanism and influencing factors of water system connectivity were studied in this paper by introducing the connectivi⁃ty index and deriving the hydraulic geometry relationship of river channel.The results show that the longitu⁃dinal connectivity depends on the relationship between the incoming water and sediment conditions and the boundary conditions.The lateral connectivity depends on the river diversion/confluence ratio,the flow pat⁃tern and the erosion and deposition pattern of the diversion/confluence area.The transverse connection in⁃cludes the coexistence of floodplain and main channel,and the exchanges of water and sediment and the spread of water organisms between floodplain and main channel during the flood period,which is mainly re⁃alized by the periodic fluctuation of flood.In addition,the main influencing factors of river connectivity are precipitation change in the basin,river regulation and embankment construction,reservoir construction and diversion works.In a word,the internal mechanism and control relationship of water system connectivity is the coordination among the incoming water&sediment conditions,diversion(confluence)condition and the boundary condition.