阿勒泰地区河流冰情特征

CHARACTERISTICS OF ICE REGIME OF RIVERS IN ALTAY PREFECTURE,XINJIANG,CHINA

本文分析了阿勒泰地区主要河流1959～1989年30年间冰情状况，初步总结了河流冰情规律。

Altay prefecture is situated at the high latitude zone in the northwestern part of Xinjiang.It is controlled by the Mongolian-Siberian cold high pressure. The ice regime of the main riversin the area appears its unique characteristics because of the long and frigid winter. The Ulungur and the Ertix River which are the two main rivers in the prefecture' are all originated from the north slope of the Altay mountains. The ice regime and its regulation of the main rivers are summarized as following. (1) The dates of first ice of the main rivers concentrated on october 1～10 and the dates in plain and mountain or in east and west does not have apparent difference.The dates of first ice are coincident with the dates of mean daily temperature below 0℃. The dates of the final ice in the mountainous rivers appear early in the west part, late in east partand later in the plain rivers. The earliest dates of final ice in the mountainous appeared on April 1～10 at the western part of Altay prefecture, on April 10～20 at the middle and eastern part and on March 20～31 in the plain rivers. The latest dates of final ice at the mountain rivers are closed to those in the plain rivers. The days from first ice to final ice of rivers at western mountain area are 10 days or more than those at the eastern mountain area, yet the difference of the days is only 1～2 day those of rivers at plain. With the increase of the elevation, the days from flrst ice to final ice of the rivers at mountain area are obviously more than those at the plain area. (2) The freeza-up dates of the mountainous rivers are on November 10～20 at the east part of the region, on November. 15～31 at the middle part and on the late December and the early January at the west part. The freeza-up dates of plain rivers at east part of the region were on November. 10～20, which have little differences to those at the west part. The meltingdates of river ice are almost concentrated on April. 1～20, which appear early at plain area,late at west mountain and later at mid and east mountain. The freeza-up days of the mountainous rivers from east to west are respectively 106 days at Kelatash Hydrometric Station and 162days at Xiaoqinghe Hydrometric Station, and those of the plain rivers have little difference fromeast to west. With the increase of the elevation, the freeza-up days are from 1O6 day at Kelatash Station on the Kaba River to 148 day at Kuwei Station on the Kayretes River. (3) Icethickness of the mountainous rivers is greater than that of the plain rivers, and ice thickness of rivers at east region is greater than that at west region. The mean ice thickness of the rivers inthe prefecture is about 1.0m, it appears from January to February. (4) Floating ice and ice-accumulated dam are the distinguishing features of the Kaba River. Floating ice piles up at theentrance of hydropower station and makes it stop working during the whole winter. In themelting period, large amount of floating ice is jammed up at the sharp curves, narrow sections and riffles forming ice dam. In case it breaks down, the flood with floating ice will cause heavy damage to the installations along the river bank.