金沙江流域汛期径流量变化的气候特征分析

Climatic Characteristics of Runoff Variation in Flood Season in Jinsha River Basin

利用金沙江流域的直门达、石鼓、小得石以及屏山4个站的径流量,以及NCEP/NCAR再分析资料和我国地面观测站逐日降水资料,研究了金沙江流域汛期(7月-9月)径流量变化的气候特征,结果表明:汛期金沙江流域径流量的年际变化趋势并不显著;直门达站径流量以2～4a时间尺度为主要振荡周期;而石鼓、屏山以及小得石站径流量在1970年前后存在显著突变,这种突变主要体现为变率突变,1970年以前振荡周期以2～4a时间尺度为主,1970年以后振荡周期则转变为以8～16a时间尺度为主;当伊朗高原至青藏高原中西部地区上空的西风水汽输送加强(减弱)时,三江源地区的降水增加(减少),有利于金沙江流域源头径流量增加(减少);当沿青藏高原南侧边缘西风水汽输送以及中国东部至日本附近地区气旋性水汽输送环流西侧的东北水汽输送加强(减弱)时,金沙江上游及雅砻江中下游沿岸降水偏多(偏少),导致金沙江中下游径流量增多(减少)。

As one of the largest rivers in southwestern China, Jinsha River is rich in water resources and hydropower resources, but at the same time, it is also an important flood zone over the upper and middle reaches of Yangtze River in flood season. Therefore, water resource as well as flood and drought changes in this region play a prominent role in the temporal and spatial distribution of water resources in China. In this paper, the data of runoff from four stations in Zhimenda （1957-2002）, Shigu （1952-2004）, Xiaodeshi （1953-2005） and Pingshan （1940-2004） hydrological stations, NCEP/NCAR reanalysis data and precipitation dataset from gauge stations were collected. Besides, by using trend analysis, correlation analysis, wavelet analysis and sliding-t test and other methods, the climatic characteristics of runoff variation in flood season （July-September） over Jinsha River were studied. The results show that： the annual variation trend of runoff is not significant in flood season; the runoff in Zhimenda station takes a time scale of 2-4 years as the main oscillation cycle; the significant abrupt change of runoff is found around 1970 in Shigu, Xiaodeshi and Pingshan stations; before 1970, the main oscillation period is of a 2-4 years time scale, while after 1970, it is of a 8-16 years time scale; the runoff change in the downstream of Jinsha River Basin is dominated by the runoff in the upper and middle reaches of the mainstream of Jinsha River and its branchs; when the westerly vapor transport over the regions from Iranian plateau to the central and western Tibetan plateau is strengthened （weakened）, the precipitation over the Three Rivers Source Region increases （decreases）, which is benefit for the increase （decrease） of runoff in the source of Jinsha River; when the westerly vapor transport along the south edge of Tibetan plateau and the northeasterly vapor transport which comes from the west side of the cyclonic moisture transport circulation are strengthened （weakened）, the precipitation along the upper reaches of Jinsha River and the middle and lower reaches of Yalong River increases （decreases）, which result in the increase （decrease） of runoff over the middle and lower reaches of Jinsha River.