A STUDY ON CHANNEL DEFORMATION AND RIVER PATTERN OF THE DOWNSTREAM CHANNEL AFTER A RESERVIOR IS CONSTRUCTED
水库下游再造床过程的若干问题

By adopting hydro-morphology theory and methods and combining with experiment in the laboratory as well, this paper deals with the following 3 aspects of problems.1 ) Longitudinal degradationDepending upon boundary conditions that is characterized by nonuniform distribution in 3 dimensional space, the development of longitudinal degradation, besides a general tendency, is getting weaker and weaker along the course with time and is also nonuniform. The degraded magnitude and the scouring distance, in general, can be determined by some experimental formulas established with measured data based on hydro-morphology theory,2 ) Lateral deformationIt is depended in a nice bit of degree upon relative erodibility of the bank to the bed. Just the same as longitudinal degradation, experimental formulas are also established, by which relationship between deformation intensity of the bank and controling factors, including boundary conditions can be represented well. Due to complex response phenomenon in adjusting process, relative erodibility of the bank to the bed decreases with time, consequently, the relationship between longitudinal and lateral deformation changes with time,too,3 ) Change of river patternIt is a very complex problem. Adjusted magnitude for width,depth, slope, relief of the bed and roughness and ways taken in adjusting process are different from each other in different river pattern. We establish a comprehensive assessment model, in which factors influencing on formation and development of river pattern are fully considered. It may be used for predicting of changes of river patterns after the reservior is constructed.