冰情影响河段测流方法研究

Measurement and computation of stream-flow during periods of ice effect

正确确定河道流量对于研究寒冷地区冬季河渠道的冰情具有重要意义.对于渠底坡度一定的冰情影响河道,即使流量一定,流动阻力增加引起水深增加,导致敞流期量测得到的水位～流量关系改变,需要重新考虑测流垂线上测点选择.为了减少量测时间、成本及恶劣天气条件下工作不便,通常并不细测垂线流速分布,而只施测少数几个点,同时利用垂向测点流速和平均流速之间关系估计平均流速.测点选择不当往往造成很大误差.本文在传统二点测流法基础上,推导得到用于确定垂线平均流速的任意二点测流法,并应用原型观测资料进行了验证.

The accurate determination of discharge is one of key problems for river-ice study in cold regions, where the river hydraulics changes greatly with the various ice conditions, such as formation of ice-cover, ice-jam and ice-dam. For an ice-affected river with a given slope,the additional flow resistance downstream increases significantly flow-depth, resulting in change of stage-discharge relationship at a given gauging station developed for open water conditions. In field observation in order to save measurement time and cost, as well as to mitigate working inconvenicence caused by severe weather,it has been customary to determine the depth-averaged velocity at some points along a path perpendicular to the flow, and then to integrate these velocities numerically to obtain the discharge. By using a weighted average of measured velocities at two arbitrary but known locations a general two-point depth-averaged method is developed. The comparisons with field measurement indicate that the method presented is sufficiently accurate.