近50 a来新疆区域与天山典型流域极端洪水变化特征及其对气候变化的响应

以年极端洪水超标率来反映区域极端洪水, 分析了新疆区域极端洪水变化; 以年最大洪峰记录分析了天山山区主要河流极端洪水变化规律, 并用14站资料分析了天山山区气候变化特征, 讨论了天山主要河流极端洪水变化对区域气候变化的响应. 结果表明: 受气候变暖影响, 1957-2006年全疆极端洪水呈区域性加重趋势, 尤其南疆区域极端洪水明显加剧, 北疆区域也有加重趋势, 但相对较缓. 全疆及北疆、 南疆在20世纪90年代中期以来都处于洪水高发阶段. 近50 a来, 在新疆区域洪水呈加重趋势的变化背景下, 发源于天山南坡的托什干河和库玛拉克河年最大洪峰流量呈显著增加趋势, 发源于天山北坡的玛纳斯河与乌鲁木齐河年最大洪峰流量虽有增加, 但是变化趋势较缓. 以年最大洪峰流量发生转折年为界, 天山典型流域托什干河、 库玛拉克河、 玛纳斯河和乌鲁木齐河在20世纪90年代(或80年代)以来与前期相比, 呈现出相似的变化特征: 年最大洪峰流量明显增大, 年际间变化更加剧烈, 洪水年更频繁. 以年最大洪峰流量发生转折年份为界, 玛纳斯河、 托什干河和乌鲁木齐河后期的年最大洪峰集中日期较前期推迟2~9 d, 库玛拉克河却提前5 d. 玛纳斯河、 乌鲁木齐河和库玛拉克河后期的集中度较前期增加0.8%~8.3%, 托什干河减小1.1%. 1961-2010年, 新疆天山山区气温明显上升, 升温率为0.34 ℃·(10a)^-1, 1997年以后明显增暖; 天山山区降水显著增加, 增加速率15.6 mm·(10a)^-1, 同时极端降水强度增大、 频数增多. 近50 a来天山主要河流极端洪水变化与区域增温以及天山山区极端降水事件增多等有密切关系.

Variations of Extreme Flood of the Rivers in Xinjiang Region and Some Typical Watersheds from Tianshan Mountains and Their Response to Climate Change in Recent 50 Years

In this paper, the flood variations were analyzed for understanding the regional extreme flood by using the rate of annual extreme flood exceeding standard in Xinjiang Region. Extreme flood characteristics of the main rivers in the Tianshan Mountains were analyzed by using annual maximum peak flood records. Regional climate change was analyzed by using meteorological data from 14 stations in the Tianshan Mountainous in recent 50 years, and the reasons causing extreme flood variation of the main rivers in the Tianshan Mountainous were discussed. The results are as follows: 1) Influenced by climate warming, the extreme flood showed regional aggravating trend from 1957 to 2006 in the region, especially in the South Xinjiang Region. In the North Xinjiang Region, the extreme flood was also aggravated, but not so serious. Since the mid 1990s, the regional extreme flood has been in high level all over the region. 2) In recent 50 years, under the background of aggravating flood in the region, the annual maximum peak floods have increased remarkably in the Tuoshikan River and the Kumalak River, which originate from the southern slopes of the Tianshan Mountainous; In the Manasi River and the Urumqi River originating from the northern slopes of the Tianshan Mountainous, the annual maximum peak floods have increased as well, but not so quick. 3) Since the 1990s (or the 1980s) all rivers mentioned above have showed a similar change: annual maximum peak discharge increasing obviously, the inter-annual change even more fierce and flood more frequent. 4) After annual maximum peak flood turning, the maximum flood peak concentration date has delayed 2~9 days than before in the Manasi River, the Tuoshikan River and the Urumqi River. However, in Kumalak River it has advanced 5 days. Annual maximum peak flood concentration has increased in 0.8 to 8.3 percent than before in the Manasi River, the Urumqi River and the Kumalak River, but it has reduced in 1.1 percent in the Tuoshikan River. 5) In the Tianshan Mountains, air temperature obviously had risen from 1961 to 2010, with a rising rate of 0.34 ℃5(10a)^-1, especially after 1997; precipitation had also increased obviously, with a rising rate of 15.6 mm5(10a)^-1. At the same time, the extreme precipitation intensity and frequency had also increased. In recent 50 years, changes in extreme floods of the main rivers have had a close relationship with regional warming and extreme precipitation events in the Tianshan Mountains.