黄河非平衡输沙典型事例及其研究概述

Two typical examples and related research of nonequilirium transportation in the Yellow River

非平衡输沙是河流泥沙运动的一个基本问题,特别象黄河这种多沙河流,非平衡输沙问题尤为突出。诸如"洪峰增值"、"驼峰"等现象,更是非平衡输沙的典型事例,一直引发世人的极大关注。本文简要总结了上述几个典型问题的前人研究成果及近几年开展的工作,认为含有极细沙的洪水在河槽中的演进,使得前期被粗化的河道阻力系数明显减小,后续洪水流速增大,与前方洪水发生叠加,形成了"洪峰增值"现象;"驼峰"河段的形成则主要是水沙条件不协调、黄河下游纵剖面影响及纵向长距离非平衡输沙造成的。

Nonequililrium transportation is one fundamental problem of sediment transportation of river,especially for the Yellow River which has a large amount of sediment.Such phenomena as,＂Flood peak increase＂,＂hump reach＂have been attracting the attention of people.This article summarizes previous research.We think roughness decrease for extra fine sediment is the major course of＂Flood peak increase＂during the course of regulated discharge regime of the Yellow River,and the formation of＂Hump reach＂is caused by inharmonic condition between water and sediment and nonequililrium and long-distance transportation of the Yellow River.