渠江流域降水时空分布特征

Spatio-temporal Heterogeneity of Precipitation Variations in Qujiang Basin

基于1961—2020年渠江流域13个气象站点降水数据,运用累积距平、Mann-Kendall检验、小波分析和Kriging插值等方法研究分析了流域降水量及暴雨事件的时空分布特征。结果表明:渠江流域60年年均降水量1126.17 mm,年降水量整体呈缓慢上升趋势,降水倾向率为6.9 mm/10 a。年降水量波动剧烈,存在27年、15年的周期性变化。年均降水量呈现由西部向东北部递增的趋势,降水量高值区位于流域东北部万源地区,低值区位于西部巴中地区。年降水量倾向率呈现由西北部向东南部递增的趋势,东部及南部降水倾向率为10~15 mm/10 a。渠江流域降水呈季节性变化,春季、秋季降水量呈下降趋势,夏季、冬季降水量呈上升趋势。5年滑动平均数据表明,夏季降水倾向率为16.9 mm/10 a,秋季降水倾向率为-7.7 mm/10 a。季节降水量波动明显,突变点较多,春、夏、秋季突变点主要集中于1961—1980年和2010—2020年间,冬季突变点集中于1985—2005年间。渠江流域春、夏、秋、冬四季降水倾向率最高值分别位于流域南部、东北部、东南部和西部。渠江流域汛期暴雨年均日数为4.28日,暴雨日数整体呈上升趋势,60年内暴雨日数以0.21 d/10 a的速率增加。汛期暴雨日数年际波动明显,1965年、1983年、1984年呈显著增加趋势。汛期暴雨日数存在14年、21年的周期性变化。渠江流域多年平均暴雨日数呈现由西南部向东北部递增的趋势,流域南部达川地区的上升趋势最快,较流域整体上升趋势高0.15 d/10 a。

Based on the precipitation data of 13 meteorological stations in Qujiang Basin from 1961 to 2020,this study used cumulative anomaly,Mann-Kendall test,wavelet analysis,and Kriging interpolation methods to analyze spatio-temporal characteristics of precipitation and extreme events variations.The results showed that the 60-year average annual precipitation was 1126.17 mm in the Qujiang basin,giving a slow upward trend with a tendency rate of 6.9 mm/10 a.The annual precipitation fluctuated violently,with cyclical changes of 27 a and 15 a.The average annual precipitation increased from the west to the northeast.The area with high precipitation was located in the Wanyuan area in the northeast of the basin,while the area with low precipitation in the western Bazhong area.The annual precipitation tendency rate increased from the northwest to the southeast,and the precipitation tendency rate in the east and south was 10~15 mm/10 a.Precipitation in the Qujiang Basin changed seasonally,with a downward trend in spring and autumn,and an upward trend in summer and winter.The 5-year sliding average indicated that the summer tendency rate was 16.9 mm/10 a,but-7.7 mm/10 a for the autumn.Seasonal precipitation fluctuated significantly with many mutation points.The mutation points in spring,summer and autumn were mainly concentrated in 1961—1980 and 2010—2020,and the mutation points in winter concentrated in 1985—2005.The highest precipitation tendency rates in spring,summer,autumn,and winter were in the south,northeast,southeast and west of the basin respectively.Heavy rainstorm days in the Qujiang basin during the flood season averaged 4.28 days per year,showing an upward trend with a rate of 0.21 d/10 a in the studied 60 years.During the flood season,it fluctuated significantly,and there was a significant increase tendency in 1965,1983 and 1984.Heavy rainstorm days in the flood season had the periodic changes of 14 a and 21 a.The multi-year average of heavy rainstorm days showed an increasing trend from the southwest to the northeast.The upward trend in the southern part of the basin-Dachuan area was the fastest,which was 0.15 d/10 a higher than the average upward trend of the whole basin.