近50 年河西地区降水量变化特征及时间分布均匀度变化

根据河西地区13个气象站点的月降水资料，利用线性倾向估计法和反距离加权法，研究了河西地区50a来降水的时空变化特征，在此基础上运用基尼系数对河西地区降水时间分布均匀度进行了分析。结果表明：河西地区年降水在20世纪60年代较少，进入70年代降水量有所增加，从2000年开始，降水量较80年代、90年代逐渐增多。河西地区的年降水、春季降水、夏季降水、秋季降水、冬季降水倾向率分别为-3．88mm／l0a、2．33mrrd10a、5．25ram／l0a、-3．27mm／l0a、-2．32mm／l0a，其中东、中部地区的冬季倾向率通过了显著性检验。河西地区降水均匀度年际变幅较大，60年代、70年代、80年代降水不均匀的区域主要集中在西部地区，步入90年代，降水不均匀的区域逐渐转移到了中东部地区，其中东部是降水不均匀度变化较为显著的地区，从长期趋势来看，河西地区降水量均匀度在时间上和空间上的波动依然会很大。

The Change Characteristics of Precipitation and Its Temporal Distribution Homogeneity in Hexi Region of China in Recent 50 Years

Hexi, located in semiarid area of northwestern China, is a commodity grain production base in Gansu. It experienced a rising trend in annual temperature, strong rainfall variability and drought frequency during the past decades. Therefore, it is necessary for us to study on climate in order to improve farming production. Based on the monthly rainfall data from 1960 to 2009 at 13 meteorological stations over Hexi area and the method of linear regression and inverse distance weight, this paper has analyzed the spatial and temporal variability of precipitation during the past 50 years, and then on this basis, it has studied the precipitation homogeneous degree in Hexi area with Gini Coefficient. The results show that annual precipitation was small in the 1960s but it began to increase in the 1970s and from 2000, its increase rate started to be larger than that in 1980s and 1990s. It was also found that the average precipitation of all areas shows the spacial diversity. The precipitation tendency rate in Hexi area is -3.88mm10a-1 in the year, 2.33mm10a-1 in spring, 5.25mm10a-1 in summer, -3.27mm10a-1 in autumn and -2.32mm10a-1 in winter, and only the winter precipation tendency rates in eastern and central regions are significant at the 0.05 level. In general, there is a large inter-annual change in precipitation. After entering 2000, the distribution of the precipitation is more and more uniform and the area with uneven precipitation also change. According to the distribution function of Gini Coefficient, the precipitation is relatively homogeneous in the 1960s and 1990s, but not in 1980s. In 1960s, 1970s and 1980s, areas with uneven precipitation were mainly concentrated in the western region but they gradually shifted to the central and eastern regions in the 1990s. Because of the fragile eco-environment, it would be a great challenge for areas with uneven precipitation to solve the problem of agriculture water. At the same time, uneven precipitation would also aggravate drought trend in some places in Hexi. From the long-term trend, the precipitation uniformity degree in space and time still show large fluctuation, which may lead to some natural disasters, such as drought, sand storm and extreme climate.