近40a来新疆河流洪水变化

Change of River Flood and Disaster in Xinjiang during Past 40 Years

随着全球变暖 ,水循环加快 ,降水量、冰川消融量和径流量连续多年增加 ,导致 2 0世纪 90年代以来新疆河流各类洪水频繁发生 ,且呈现出峰高量大的特征 .近 4 0a来洪水灾害的频次呈逐年增加趋势 ,尤其是 1987年以来 ,洪灾发生的频次增高 ,灾害损失成 10倍增加 .

The flooded area of Xinjiang was only 4\^28×10\+4 hm\+2 to 5\^22×10\+4 hm\+2 during 1950s to 1970s, but it suddenly increased to 36\^47×10\+4 hm\+2 in 1987. This reflects the climate mutation. The large flood caused by the heavy storm and the rapid glacier and snow melt under the high air temperature weather conditions can be considered as the climatic extreme events. A statistical analysis is carried out on the yearly maximum flood discharge. During the 45 years from 1956 to 2000, the deluge happened 56 times, and among them, during the 14 years from 1987 to 2000 it happened 27 times accounting for 48%. Among the 28 times of the extraordinary flood during 1956 to 2000, 21 times happened in the years from 1987 to 2000 accounting for 75%. As the IPCC report Chapter \!Observed climate variability and change\' points out that the total precipitation increases in various regions, while the increase of the large or extreme precipitation events is more obvious. Among all of the previous flood disasters, the most serious is in 1996, when 8 rivers had the records of first class flood, 5 rivers had the records of second class flood, causing the direct economic loss accounting for 7% of the GDP in Xinjiang that year. In 1999, 24 rivers in Xinjiang had the records of the first class flood and 7 rivers the second class flood, when the many years not appeared glacier dammed outburst flood occurred at the Yarkant River, and the flood discharge reached \{6 070\} m\+3\5s\+\{-1\} at the Qiaqun Hydrological Station. In 2002, the extraordinary flood of over 100 years return period occurred for the Weigan River at the south flank of the Tianshan Mountains, and the continuous heavy precipitation and rapid glacier melt formed and enhanced the deluge during the days from 19 to 23 of July, destroying two big reservoirs and the flood discharge reached to \{3 540\} m\+3\5s\+\{-1\}, causing the serious disasters of the Baicheng, Shaya, Xinha and Kuqa 4 counties.