近60年来南四湖流域降水变化特征分析

Variability of Precipitation in Nansi Lake Basin in Recent 60 Years

为研究气候变化背景下南四湖流域降水的时空分布特性,利用流域8个主要雨量站点1952—2011年日降水资料,基于水文特征时间序列法、Co-Kriging插值、小波分析等方法,分析了近60年来流域降水的时空演变特征。研究表明:(1)流域多年平均降水呈不显著减少趋势,从东向西递减趋势增强;(2)降水量的空间分布具有较明显的季节差异:夏季降水围绕薛城、藤县、鱼城站形成降水的强高值中心,降水高值区影响范围远大于多年平均水平,冬季降水较少,等值线分布比较均匀;(3)受季风环流的强弱和活动范围不同的影响,流域存在明显的降水突变与振荡。降水年际周期变化中,10a时间尺度下经历了9次强烈振荡周期,是降水的第一主周期;22a时间尺度为第二主周期,经历4次振荡。根据降水年内分配与主周期振荡趋势特征,可预测流域未来降水变化趋势与空间特征,为预防水旱灾害、合理利用水资源提供依据。

In order to reveal the spatiotemporal distribution characteristics of the precipitation in Nansi Lake basin under the background of climate change,we analyze the spatiotemporal evolution of precipitation in the basin using daily precipitation data of eight major rainfall stations from 1952 to 2011.The methods involved in this paper include hydrological time series analysis,Co-kriging,and wavelet analysis.The results indicate that:(1)the multi-year average rainfall in the basin presents a slight decreasing trend and the decreasing trend becomes more obvious from east to west;(2)the spatial distribution of precipitation shows obvious seasonal difference:precipitation in summer which is revolved around areas like Xuecheng,Tengxian and Yuchengzhan has formed a very strong center of high value in precipitation;the influence range of high value area is much larger than average level;the precipitation in winter is much less than other period;therefore,the precipitation contour distribution is relatively uniform;(3)the obvious changes and oscillation in precipitation in the basin are found due to the variation in the intensity and range of the monsoon circulation;in the precipitation inter-annual period,nine strong oscillation periods are found in 10 years scale,which is the first main period of precipitation;22-year scale is the second main cycle,which experiences four oscillations;according to the distribution of precipitation in a year and the main trend of periodic oscillation characteristics,we can predict the precipitation change trend and spatial characteristics in the basin in the future,which can provide support for preventing floods and rational utilization of water resources.