影响三工河干沟春季融雪洪水发生的气象因素

利用三工河流域近山前倾斜平原区气象资料，对发生在1964-2001年期间三工河干沟春季洪水量进行逐步回归分析，得到2个相关性较好的三元模型方程。模型表明，冬季积雪量越大，3月1候前期气温越低，3月2候气温越高，三工河春季洪水量就越大，反之则相反。模型中的2项气象因素是制约三工河干沟发生春洪的主要条件因素，因此，三工河流域开春期前的增温作用是近年来三工河干沟春季洪水量减少的主要原因。

Analysis on the Meteorological Factors Affecting the Occurrence of Snow-melt Floods in Gangou Stream in the Sangong River Watershed

The Sangong River Watershed is located in the northern slope of the Bogda Mountain in the east Tianshan Mountains and southern marginal zone of the Junggar Basin.In the watershed it belongs to the arid continental climate,winter is long and cold,seasonal snowcover duration is about 110 days from mid-or late-November to early-or mid-March.In the mountainous regions,snow-melt floods occur frequently in March,they are characterized by the short duration and high peak discharge,threaten the safety of highways,reservoirs,irrigation works and people's life,and result in some heavy economic losses in the lower reaches of the Sangong River.In this paper,the snow-melt floods occurred in Gangou Stream in the Sangong River Watershed in spring during the period of 1964-2001 are analyzed based on the meteorological data observed in the fore-mountain sloped plain in the Sangong River Watershed,and 2 ternary model equations with high correlation are derived.The study results are as follows:(1) Air temperature in March and seasonal snowcover in winter in the fore-mountain sloped plain are the main factors affecting snow-melt floods in spring in the Sangong River Watershed;(2) Flood discharge in the Gangou Stream is increased with the increase of seasonal snowcover,decrease of air temperature in the first pentad and increase of air temperature in the second pentad,and the change of air temperature(the temperature difference between the first pentad and second pentad) is the main factor affecting the flood discharge in spring;(3) Air temperature is a dominant factor affecting the occurrence of snow-melt floods in spring in the Sangong River Watershed,the air temperature before the first pentad of March affects the snow accumulation in winter,and that after the second pentad of March affects the snow melt intensity in spring.