2019—2020年度黄河头道拐断面冰厚增长影响因素分析

Analysis on the Influencing Factors of Ice Thickness Growth at Toudaoguai Section of the Yellow River During Winter of 2019-2020

为了解黄河干流同一断面冰厚增长差异及其产生原因,依据2019—2020年度冬季对头道拐断面封冻期原型观测数据,分析冰厚增长方式以及负积温、流速、冰花等对冰厚增长的影响。结果表明:头道拐断面冰层上层由冰花冻结形成;距左岸400~500 m为非主流区且区间内测点的冰生长方式为热力学生长,主要形成柱状冰;距左岸500~740 m为主流区且区间内测点的冰生长方式以冰花堆积冻结为主,测点之间的冰厚差异大。随着冰厚的不断增长,冰厚单位度日增长量逐渐减小;冰层底部有冰花堆积的冰厚单位度日增长量大于无冰花堆积的情况;当冰厚增长到一定厚度时,有冰花和无冰花的冰厚单位度日增长量趋于一致。负积温是冰厚增长的主要影响因素,流速对冰厚增长有抑制作用,冰层底部存在冰花对冰厚增长有促进作用。

The research purpose of this paper is to obtain the information on the difference in ice thickness increase on the same section of the main stream of the Yellow River and its causes.Based on the data collected from observing the section freezing period at the Toudaoguai Hydrological Station in the winter between 2019 and 2020,the author analyzed the impact of ice thickness increase method,freezing degree days and flow velocity on the increase of ice thickness.The research results illustrates that the upper layer of the ice cap on the Toudaoguai section is formed by freezing ice.The area ranging from 400 m to 500 m of the left side bank is the non⁃mainstream zone and the ice increase at the measuring points in the interval is thermodynamic growth,mainly forming columnar ice.The area ranging from 500 m to 740 m of the left side bank is the mainstream zone and the ice increase at the measuring points in the interval is mainly ice accumulation and freezing,with relatively apparent difference in ice thickness.With the continuous increase of ice thickness,the daily increase of ice thickness is gradually decreased.The daily increase of ice thickness with frazil ices at the bottom of the ice layer is greater than that without frazil slush accumula⁃tion.However when the ice thickness increases to a certain degree,the difference disappears.Freezing degree days is the main factor influen⁃cing the increase of ice thickness.The average velocity of the vertical line inhibits the increase of ice thickness.The presence of frazil ices at the bottom of the ice layer can promote the increase of ice thickness.