冲积河流的极限流速

Limit velocity for alluvial rivers

为了说明天然冲积河流存在极限流速,整理了长江、松花江等20条冲积河流上25个水文站的日均流量、日均水位、实测大断面、日均含沙量等水文资料,利用水流连续性方程,由日均流量和过水断面面积求出断面平均流速。结果表明,天然冲积河流断面平均流速随着流量的增加而增大,达到一定流量后,断面平均流速趋近于一个极限流速。天然冲积河流流量较大时通过增加过流断面面积使得流速始终低于极限流速。人类活动会影响冲积河流的极限流速。

In alluvial rivers that have not been affected by human development, the flow velocities vary within a limited range. This range was studied by analyzing hydrological data, including daily average discharges, sediment concentrations, stages, and cross sections from hydrological stations collected from 25 stations on 20 rivers in China, including the Yangtze, Songhua Rivers, etc. The cross-sectional average velocities were calculated from the discharge and wet area. For alluvial rivers, the wet cross section changes with the discharge so that the flow velocity does not exceed some limit as the discharge exceeds the bankfull discharge. Human activities change this limit velocity for alluvial rivers depending on the intensity of human activity.