大西安地区降水资源空间差异较大,为深入了解大西安不同区域降水时空分布特征,利用大西安地区14个气象站1970—2013年的逐月降水观测资料,采用滑动平均法、Mann-Kendall检验法、小波分析法以及克里金插值法,对大西安5个区域降水量的时空变化特征进行了分析。结果表明:大西安地区年均降水量为576.65 mm,整体呈下降趋势,下降率为-10.04 mm/(10 a),东部较西部下降显著,北部较南部下降显著;年内降水量分配不均,降水主要集中在7—9月份,占全年降水总量的50.84%,春、秋季降水量呈下降趋势,夏季降水量呈上升趋势;研究区年降水量变化的第1主周期为28 a;全区多年降水量呈现出少—多—少—多的波动趋势,突变年份为1980年和1991年;年代际降水量呈现出增加—减少—增加的趋势;年降水量空间分布不均,呈现自东南向西北逐渐减少的趋势。上述研究成果可为大西安地区降水资源的合理利用提供参考。

The spatial distribution of precipitation is uneven in Big Xi'an region. According to the monthly precipitation data from 14 meteorological stations in Big Xi'an during 1970-2013, we analyzed the spatial and temporal variations of precipitation in five areas of Big Xi'an region by using moving average method, Mann-Kendall test method, wavelet analysis method and the Kriging interpolation method. Results show that the average annual precipitation in Big Xi'an region was 576.65 mm, decreasing overall with a rate of -10.04 mm/10 a. Decreases in precipitation in the east and north of Xi'an were more obvious than those in the west and south. Moreover, the distribution of precipitation in a year was uneven, mainly from July to September, accounting for 50.84% of the total annual precipitation. In addition, precipitations in spring and autumn presented a downward trend, but precipitation in summer was in an upward trend. The first main period of annual precipitation change in the study area was 28 years. Precipitation in multiple years in the area experienced a fluctuation in “less-more-less-more” trend, with abrupt changes in 1980 and 1991; but interdecadal precipitation in the study area showed a trend from increase to decline and then to increase. In addition, the spatial distribution of annual precipitation is uneven, gradually decreasing from the southeast to the northwest. The research results could offer reference to the rational utilization of precipitation resources in Big Xi'an region.