近40年三峡库区面雨量时空分布特征

Distribution Characteristics of Area Rainfall in the Three Gorges Reservoir for Recent 40 Years

  • 摘要: 利用1980—2016年逐日雨量观测资料,以站点平均法计算库区面雨量,得到以下结论:三峡库区年面雨量的年际差异大,且37年以来呈现缓慢下降的趋势;月面雨量的峰值出现的月份,重庆—万州为6月,万州—宜昌为7月;从日强降水面雨量特征来看,三峡库区强降水面雨量主要出现在5—9月,万州—宜昌强降水出现的总数明显高于重庆—万州,且在各个量级都是万州—宜昌明显多于重庆—万州;从日面雨量极值分布来看,面雨量极值一般出现在6—7月,万州—宜昌69.9mm以下的各级强降水均是7月出现最多,70mm以上的强降水则都是6月出现最多,这与重庆—万州段恰好是相反的;从两子流域各个量级降水的年均频次分布上来看,20~29.9mm的降水,每年各有7~9次,30~49.9mm的降水,每年各有5~7次,上述几个量级出现的频次相对较高;50~69.9mm的降水,每年各有1~2次,对于70mm以上的降水,平均2~5a才1次,可见50mm以上降水出现的频率低,而造成的影响又较大,应在后期重点研究其形成机理。

     

    Abstract: Using the daily rainfall data in years of 1980-2016, the area rainfall is calculated by means of site average method, and the following conclusions are obtained. The annual area rainfall in the Three Gorges Reservoir showed great interannual fluctuation with a slow decline trend in the 37 a; The peak of monthly area rainfall appearsed in June in Chongqing to Wanzhou, while in July in Wanzhou to Yichang region; The heavy area rainfall mainly occurred in may to September. The total number of heavy area rainfall in Wanzhou to Yichang was signi ficantly higher than that in Chongqing to Wanzhou region, even in all rainfall levels; The extreme values of area rainfall generally appeared in June to July. The heavy area rainfall below 69.9 mm occurred generally in July, while that above 70 mm was in June. It is exactly the opposite between the 2 subbasins of Wanzhou to Yichang and Chongqing to Wanzhou. The area rainfall of 20 to 29.9 mm occurred 7~9 times, of 30 to 49.9 mm 5~7 times, of 50 to 69.9 mm 1~2 times per year in each subbasin. The area rainfall above 70 mm occured once per 2~5 years. The area rainfall above 50 mm was in low frequency but great infuences, and their synoptic mechanism should be investigated further in the future.

     

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