近30年祁连山南坡降水量变化特征分析

Analysis of Precipitation Variation Characteristics in the Southern Slope of Qilianshan Mountains in Recent 30 Years

祁连山南坡地区作为西北干旱区重要的水源涵养区,其生态地位十分重要,而降水的变化直接关系到祁连山南坡水源涵养量的变化,甚至可以改变祁连山南坡的生态环境。因此,研究祁连山南坡降水量变化特征具有重要的社会和科学意义。利用1986—2015年祁连山南坡祁连、野牛沟、托勒和门源4个气象台站逐月降水量数据,通过降水年内分配特征、年际变化特征、汛期降水量特征和降水量季节变化特征4个方面,对祁连山南坡降水量变化特征进行了综合分析。结果表明:研究区各站近30年平均降水量分别为422.7 mm,434.3 mm,312.7 mm和524.1 mm,祁连气象站、野牛沟气象站和托勒气象站均在1998年出现降水量极大值,与全国降水时间分布规律一致,各站降水量年际变化不大,变差系数为0.14～0.18;研究区降水年内分配极不均匀,10月至次年4月降水量偏少,5—9月降水量较多;汛期降水量与全年降水量具有较大的一致性和良好的线性相关关系,相关系数均大于0.9;研究区内各站降水量主要集中在夏季,但变化趋势不同,其中祁连、野牛沟和托勒气象站降水量为增加趋势,门源气象站降水量为减少趋势。

The southern slope area of Qilianshan Mountains is an important water source conservation area in the arid area of northwest China, and its ecological status is very important. The change of precipitation is directly related to the change of water source conservation in the southern slope of Qilianshan Mountains, and can even change the ecological environment of the southern slope of Qilianshan Mountains. Therefore, it is of great social and scientific significance to study the variation characteristics of precipitation in the southern slope of Qilianshan Mountains. The characteristics of precipitation variation in the southern slope of Qilianshan Mountains was analyzed by using the data of monthly precipitation(1986—2015) of four meteorological stations in Qilian, Yeniugou, Tuole and Menyuan. The results showed that, in recent thirty years, the average annual precipitation of the Qilian, Yeniugou, Tuole and Menyuan meteorological station was 422.7 mm, 434.3 mm, 312.7 mm and 524.1 mm, respectively, the precipitation maximal values of Qilian, Yeniugou and Tuole meteorological stations occurred in 1998, which was consistent with the distribution pattern of precipitation time in China. The precipitation of each station had little change each year, and the coefficient of variation ranged from 0.14 to 0.18;the distribution of precipitation in the study area was extremely uneven during these years, and the rainfall was less from October to the next April, but more from May to September. There were not only significant consistency but also good linear relationship between flood season precipitation and yearly precipitation, and all the correlation coefficients were greater than 0.9. The precipitation in each station mainly concentrated in summer, but had different variation trends. The precipitation of Qilian, Yeniugou and Tuole station was increasing but the precipitation of Menyuan was decreasing.