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| DOI：10.13522/j.cnki.ggps.2020026 |
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| Characteristic Analysis of the Heavy Rains During Monsoon Season in Zishui Basin of Hunan Province |
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LI Bing, WEN Qiang, ZHANG Xinping, YANG Ling, LIU Dianying, YANG Leqing
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1. Yiyang Meteorological Bureau, Yiyang 413000, China; 2. Hunan Normal University College of Resources and Enviromental Sciences, Changsha 410081, China
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| Abstract: |
| 【Background】Hunan is a province in south China characterized by frequent occurrence of heavy rains. While spatiotemporal variation in storms across China has been studied intensively, there is still a lack of quantitative analysis of them.【Objective】The objective of this paper is to take the Zishui river basin as an example, presenting a method to systematically study the characteristics of heavy rains during monsoon season (April-September) in typical river basins in Hunan province.【Method】The analysis was based on data measured from 14 weather stations across the Zishui basin in 1980—2016. The spatiotemporal variation in the rainstorms was analysed using the EOF decomposition, global Moran Index, Mann-Kendall test. The probability of storms in each weather station was calculated based on statistical theory.【Result】①Duration of the heavy rains varied spatially across the basin, with heavy rains in the middle of the basin lasting longer than that in other parts. ②The EOF decomposition found a basin-scale storm mode and a north-south mode. The global Moran index showed less rainstorms in the 1980s while more in the 1990s. Spatially, storms in the middle and lower reaches of the basin were more than that in other parts. ③Duration of the storms and storm intensity had both increased at an annual rate of 0.1day and 13.1millimetre, respectively. ④The storms in the basin were temporally uneven, with the mean precipitation concentration degree (PCD) and the mean precipitation concentration period (PCP) being 0.82 and 26 June respectively. ⑤The probability of having a storm occur in the basin in 10 days during the monsoon season was low, and the probability of having a heavy storm in 20 and 30 days was 23.1% and 32.2% respectively. On average, Anhua county is most likely to see storms with the probability of having a storm in 20 and 30 days being 39.1% and 46.0% respectively. |
| Key words: Hunan province; Zishui river basin; monsoon season; heavy storm |
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