1971-2018年汉江流域陕西段降水时空特征分析

基于1971-2018年汉江流域陕西段 27个气象站点的逐日降水数据，选择了年降水量、降水强度、最大日降水量、年降水日数、中雨日数和大雨日数6个降水指数分析其降水时空特征，分析方法包括线性估计法、小波分析法、滑动均值法、IDW 空间插值法及Mann-Kendall检验法。结果表明：在研究时段内，汉江流域陕西段降水强度有缓慢增加趋势，其余5个降水指数均呈缓慢减小趋势，且6个降水指数的变化趋势均不显著；研究区域仅年降水日数无突变点，且在1995年后呈现显著减小趋势，其余降水指数均有突变点；年降水量有7 a的副周期和27 a左右的主周期，主周期有3个循环交替，且丰、枯交替突变点在1983和2000年。汛期降水量与年降水量周期基本一致，而非汛期有4和16 a两个副周期和1个28 a的主周期；年降水量空间分布呈现由北到南逐渐增大的趋势，除了年降水日数的高值中心在宁强县外，其余5个降水指数的高值中心均在镇巴县，而低值中心除了降水强度在太白县外其余的均在商县。在研究时段内各年代际降水指数的比较中，1971-2018年的年降水量、降水强度和年降水日数均仅次于最大值，预计未来极端降水事件可能更加频繁，严重的情况下会影响水生态、水环境、水安全等的健康发展。

Spatial and temporal characteristics of precipitation in Shaanxi section of Hanjiang River Basin during 1971-2018

Based on the daily precipitation data of 27 meteorological stations in Shaanxi section of Hanjiang River Basin from 1971 to 2018, six precipitation indexes including annual precipitation, precipitation intensity, maximum daily precipitation, annual precipitation days, moderate rainfall days and heavy rainfall days were selected to analyze the spatial and temporal characteristics of precipitation in this area using linear trend, wavelet analysis, moving average, IDW spatial interpolation and Mann-Kendall abrupt test methods. The results showed that the precipitation intensity in Shaanxi section of Hanjiang River Basin presented a slow increasing trend, whereas the other five precipitation indexes presented a slow decreasing trend, but all the changes were insignificant. There were abrupt points in all the indexes except annual precipitation days, showing a remarkable decreasing trend after 1995. Annual precipitation had a secondary cycle of 7 a and a main cycle of about 27 a consisted of three alternative dry-wet cycles, with the occurrence of abrupt points in 1983 and 2000. The precipitation cycle in the flood season was consistent with that in non-flood season, but the non-flood period had two secondary cycles of 4 a, 16 a and a main cycle of 28 a. The spatial distribution of precipitation showed a progressive increasing trend from north to south. Except for the high value center of annual precipitation days in Ningqiang County, that of the other five precipitation indexes were all in Zhenba County, whereas the low value center of all the indexes were in Shang County apart from the precipitation intensity which was in Taibai County. The comparison analysis showed that the values of annual precipitation, precipitation intensity and annual precipitation days from 1971-2018 were only second to the maximum values. Extreme precipitation events are likely to happen more frequently in the future, resulting in water disasters which will affect the healthy development of water ecology, water environment and water security in severe cases.