新疆叶尔羌河突发洪水规律研究

THE FORMATIVE LAW OF FLASH FLOOD IN YARKAND RIVER, XINJIANG

叶尔羌河灾害性突发洪水系由冰川阻塞湖泄洪所致。通过三年野外考察(1985～1987年)和详尽分析洪水的特点、分布及成因,归结叶尔羌河灾害性洪水发生规律如下:①大部分是由叶尔羌河上源的克亚吉尔特索湖迅速排水所致。②洪水多出现在8月底至9月中旬,迟於年内最高气温出现日期;洪水多出现在≥5℃积温的峰值年份,和夏季(6～8月)600hPa高空气温的峰值时期。③实测克亚吉尔特索湖岸边有134条湖水侵蚀-堆积线,它们深刻地反映了该冰川湖的演变过程。冰川湖突发洪水则随着冰川退缩、冰湖缩小而减弱。

The disastrous flash floods in Yarkand River were caused by the dewatering of glacier-dammed lakes. According to the detailed analysis of characters, distributions and formations of the floods, together with three-year expeditions (ly85-1987), the formative Jaw of this kind of flood is described as follows: (1) Most of the floods were caused by the dewatering of Kyagar Thso Lake distributed in the upper end of Yarkand River. (2) Most of the floods occurred from the end of August to the middle of September, later than the occurrence period of annual highest temperature, but coincident with the occurrence of the maximum value of the≥5℃ cummulative temperature and the summer air temperature at the 600 hPa height. (3) The results of measurement in Kyagar Thso Lake area show that there are 134 stripes of lake water erosion-sedimentary marks on the lake banks, reflecting the evolution of the Kyagar Thso Lake. The flood discharge and its volume caused by glacier-dammed lake were reduced as the retreating of Kygar Glacier.