Analysis of spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin
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摘要: 全球气候变暖和快速城市化进程影响降水结构,导致极端水文气象事件频发。为研究变化环境下太湖流域湖西区暴雨时空分布特性,选取1961—2015年湖西区多个雨量站的降水资料,分析了暴雨指标(年暴雨日数、年暴雨量、年暴雨强度、年暴雨贡献率)变化特征,并计算出给定重现期下的年最大日降水量值。结果表明,湖西区年降水量自北往南逐渐增加,年暴雨日数和年暴雨量均呈现中部较低、南北两侧较高的分布,年暴雨强度自西南往东北先增大后减小,年暴雨贡献率在西南地区偏小;湖西区宜兴站近55年年暴雨日数、年暴雨量、年暴雨贡献率呈显著上升趋势;自2005年起湖西区各暴雨指标表现出显著上升趋势;金坛站和丹阳站年均最大一日降水量高于溧阳站和宜兴站,并且各雨量站5年一遇的年最大日降水量均超过了100 mm,达到了大暴雨水平,其中金坛站和丹阳站较易发生极端降水事件。Abstract: Global warming and rapid urbanization development would affect the rainfall structure (i.e., variability in space and time) and the frequency of extreme hydrometerological events. To analyze the spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin (TLB) in the changing environment, daily rainfall data from rainfall stations from 1961 to 2015 are analysed to determine the spatial and temporal trends of 4 rainstorm indices (annual days, rainfall, intensity and percentage of rainstorms). Furthermore, the annual maximum daily rainfall for the specific return period is calculated. The results show that: (1) Annual rainfall increases from the north to the south, while annual days and rainfall of rainstorms decrease from the north and south to the center in the western region of TLB. Annual intensity of rainstorms increases firstly, and then reduces from the southwest to the northeast, while annual percentage of rainstorms in the southwest is lower than other places in the western region of TLB. (2) Annual days, rainfall and percentage of rainstorms at Yixing station have risen sharply from 1961 to 2015. (3) From 2005, there is a significant increase in all the rainstorm indices in the western region of TLB. (4) The average annual maximum daily rainfall at Jintan and Danyang stations appear higher than those at Liyang and Yixing stations. (5) The annual maximum daily precipitation for 5-year return period at the 4 representative stations (i.e., Danyang, Jintan, Liyang, Yixing stations) all exceed 100 mm to be classified as heavy rainstorms. Particularly, Jintan and Danyang stations are prone to suffer from extreme rainfall events compared with Yixing and Liyang stations.
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Key words:
- rainstorm /
- annual maximum daily rainfall /
- return period /
- Taihu Lake Basin /
- principle of entropy
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表 1 湖西区各站暴雨指标趋势检验结果
Table 1. Trend test analysis of rainstorm indices in the western region of TLB
站点 暴雨指标 统计量Z 趋势 显著性 站点 暴雨指标 统计量Z 趋势 显著性 丹阳站 年暴雨日数 (d) 0.17 上升 不显著 溧阳站 年暴雨日数 (d) −0.68 下降 不显著 年暴雨量 (mm) 0.30 上升 不显著 年暴雨量 (mm) −0.11 下降 不显著 年暴雨强度 (mm·d−1) 0.80 上升 不显著 年暴雨强度 (mm·d−1) 0.88 上升 不显著 年暴雨贡献率 0.25 上升 不显著 年暴雨贡献率 −0.28 下降 不显著 金坛站 年暴雨日数 (d) 0.01 上升 不显著 宜兴站 年暴雨日数 (d) 2.71 上升 显著 年暴雨量 (mm) 0.33 上升 不显著 年暴雨量 (mm) 2.75 上升 显著 年暴雨强度 (mm·d−1) −0.10 下降 不显著 年暴雨强度 (mm·d−1) 1.05 上升 不显著 年暴雨贡献率 0.29 上升 不显著 年暴雨贡献率 2.08 上升 显著 表 2 m阶矩约束下POME分布对应AIC值
Table 2. AIC values for POME-based distributions with constraints of m orders of moments
雨量站 m=2 m=3 m=4 m=5 m=6 m=7 m=8 丹阳 −37.98 −53.43 −54.07 −52.31 −53.14 −51.38 −52.33 金坛 −33.78 −35.23 −33.37 −33.80 −32.12 −32.18 −33.03 溧阳 2.48 0.48 2.10 3.76 5.75 7.47 4.76 宜兴 −14.03 −14.93 −13.89 −12.17 −10.35 −9.00 −8.72 -
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