新疆天山北坡四棵树河冰洪分析

四棵树河是新疆天山北坡的一条灾害性较大的河流,除了夏季洪水致灾外,另一种更引人注目的是冬季冰洪突发成灾.从该河流的自然地理条件分析入手,阐述了该河独特的冰洪特征,结合气温、地形等影响因素分析了四棵树河的冰洪成因.冰洪形成往往与当时当地的气温和地形变化有关.因气温逐渐或突然升高,冰骨架结合力下降,当虚冰坝阻水形成的水压力超出了冰骨架支撑力时,上游某一虚冰坝破裂垮塌,冰水则迅猛下泄,致使下游虚冰坝连续垮溃形成河流冰洪.此外,对冰洪沿程变化、冰洪量差异显著、冰洪年际变化不均、稳定封冻期及解冻期不出现冰洪的原因也进行了分析.

Analysis of ice-flood in Sikeshu River basin on the north slope of Xinjiang Tianshan mountain

Sikeshu River on the north slope of Xinjiang Tianshan mountain is a calamitous river. Besides summer flood the bursting ice-flood causing disaster in the winter is more remarkable. Starting with the analysis of its condition of physical geography, this paper elaborates the particular characteristics of the ice-flood, and analyzes the cause of formation of ice-flood combined with air temperature and terrain factors. Formation of ice-flood is related to the changes of air temperature and terrain. When air temperature rise gradually or suddenly, the force of combination of ice-dam framework decline. While the water pressure caused by ice-dam exceed the support force of ice-dam framework, a certain loose ice-dam of the upper reach burst, ice water flow swift to the lower reach, thus brought out a series of collapsed ice-dam and forming ice-flood. Moreover, the ice-flood evolvement and the reasons of the notable difference of ice-flood volume, nonuniformity of annual change of ice-flood and no ice-flood in stable period of ice-cover or melting period etc are also analyzed.