宁夏中部干旱区降水量及可利用降水量多时间尺度变化特征分析

Variation in Precipitation and Net Precipitation in Arid Area in Central Ningxia

【目的】研究1969—2020年宁夏中部干旱区降水量及可利用降水量在不同时间尺度的变化特征,为当地的水资源利用以及灾害防治提供参考依据。【方法】基于1969—2020年宁夏中部干旱区6个气象站降水量及月平均气温资料,采用高桥浩一郎蒸散发公式、气候趋势法、Mann-Kendall突变检验以及小波周期分析,对宁夏中部干旱区降水量及可利用降水量在不同时间尺度下的分配情况、丰欠演变趋势及周期规律进行研究。【结果】①宁夏中部干旱区西北区与东南区降水资源差异较大,降水量分别为188.0 mm和304.1 mm,可利用降水量分别为17.8 mm和58.9 mm。②宁夏中部干旱区降水主要集中在夏季,占全年57%左右;冬季最少,仅占全年3%,且年内和年际变化平缓;春、冬季可利用降水率低。③宁夏中部干旱区年际间降水资源年际间将由波动期向干旱期变化;东南区的极端降雨现象比西北区更明显,西北区在2013年以前可利用降水资源较为丰富。④趋势分析表明未来东南区年降水量及可利用降水量分别以1.539、0.467 mm/a速率显著增加,西北区降水量以0.647 mm/a显著增加、可利用降水量以0.073 mm/a的降幅减少,但无显著性;突变分析表明2010年为宁夏中部干旱区降水量开始发生突变的年份。⑤宁夏中部降水量及可利用降水量主要以9、12~13、40 a为主周期,对应的振荡周期分别为6、9、25 a。可利用降水变率较大,对农牧生产活动影响较大。【结论】宁夏中部干旱区各降水资源东南区比西北区更丰富;季节年降水量及可利用降水量排序均为夏季>秋季>春季>冬季;未来降水量及可利用降水量有显著上升趋势,降水资源向着大周期尺度演变。

【Objective】Precipitation and evapotranspiration are two important parameters required in hydrological modelling and water resource management.In this paper,we analyzed their temporal variation in the arid area in central Ningxia province.【Method】The analysis was based on precipitation and monthly average temperature measured from 1969 to 2020 from six meteorological stations across the area.Spatiotemporal variation in the precipitation and net precipitation(the difference between precipitation and evapotranspiration)was calculated using the Koichiro Takahashi's evapotranspiration formula,climate trend method,Mann-Kendall mutation test and the wavelet cycle analysis.【Result】①The precipitation in northwest and southeast of the area differed considerably,with the precipitation in the former and the latter being 188.0 mm and 304.1 mm,and their associated net precipitation being 17.8 mm and 58.9 mm,respectively.②Rainfall in the area falls mainly in summer,accounting for 57%of the annual precipitation,while precipitation in the winter is the least,accounting for only 3%of annual precipitation.The net precipitation in spring and winter is lower than that in other seasons.③Interannual variation in net precipitation has been in a transition from fluctuations to continued drying in the studied period.The extreme rainfalls were mainly in the southeast,and the net precipitation in the northwest was more abundant before 2013 than after 2013.④Trend analysis shows that the annual precipitation and net precipitation in the southeast have increased significantly at 1.539 mm/a and 0.467 mm/a,respectively.In contrast,the precipitation in the northwest had increased at 0.647 mm/a,while the net precipitation had been decreasing at 0.073 mm/a though not at a significant level.Mutation analysis showed an abrupt precipitation change in 2010.⑤Precipitation and net precipitation in the studied area showed periodicities of 9,12~13,40 a,with their associated oscillating periods being 6,9 and 25 a,respectively.The net precipitation varied largely,having a greater impact on agriculture and animal husbandry.【Conclusion】Precipitation and net precipitation in the southeast is more abundant than in the northwest of the studied area.The magnitude of seasonal annual precipitation and net precipitation are ranked in the order of summer>autumn>spring>winter.Precipitation and net precipitation in the studied area have been increasing over the studied period.