基于不同地形因子的重庆市短时强降水时空变化特征分析

Analysis of Temporal and Spatial Variation Characteristics of Short-term Heavy Precipitation in Chongqing Based on Different Landforms

为探讨短时强降水频次和强度与地形因子的关系,基于SRTM数字高程DEM模型,利用重庆地区加密观测的2017~2021年5~9月逐小时降水资料,对比分析重庆市不同地形下短时强降水的时空分布特征。结果表明,重庆市短时强降水空间分布不均,总体上年均频次高值区和≥60 mm/h的站点主要位于渝西北的华蓥山、渝东北的大巴山、渝东南的武陵山附近。对于重庆市短时强降水的站均频次,月间变化呈显著单峰型,且7月发生频次最多;日内变化呈双峰型,主波峰以03:00~05:00时发生频次最多、次波峰以16:00~19:00时发生频次较多。偏北、偏西较其他坡向的频次略微偏多;平坡、缓坡较其他坡度的频次多;海拔500~1000 m、>1500 m较其他海拔的频次多;起伏度≤30 m、30~200 m较其他起伏度频次多;当坡度≤15°、海拔≤1000 m、起伏度≤200 m时,出现了降水强度≥100 mm/h的站点,说明适当的山地地形有利于短时强降水强度的增加。研究成果可为重庆市短时强降水临近预警、防灾减灾提供参考。

Based on the SRTM digital elevation DEM model,using the hourly precipitation data of Chongqing from May to September 2017 to 2021,this paper analyzed the temporal and spatial distribution characteristics of short-term heavy precipitation under different terrains in Chongqing,and discussed the relationship between the frequency and intensity of short-term heavy precipitation and topographic factors.The results show that the spatial distribution of short-term heavy precipitation in Chongqing is uneven.The overall average frequency high value area of the previous year and stations≥60mm/h are mainly located near Huaying Mountain in Northwest Chongqing,Daba Mountain in Northeast Chongqing and Wuling Mountain in Southeast Chongqing;For the station average frequency of short-term heavy precipitation in Chongqing,the monthly variation shows a significant single peak type,and the frequency is the most in July;The diurnal variation is bimodal,with the main peak occurring most frequently at 03:00-05:00 and the secondary peak occurring more frequently at 16:00-19:00.The frequencies of the north and west slopes are slightly more than those of the other slopes.The frequency of flat slope and gentle slope is more than that of other slopes.The frequency of 500-1000 m and>1500 m is more than that of other altitudes;The fluctuation≤30 m and 30-200 m are more frequent than other fluctuations;When slope≤15°,altitude≤1000 m,and undulation≤200 m,stations with precipitation intensity≥100 mm/h appear,indicating that appropriate mountain topography is conducive to the increase of short-time heavy rainfall intensity.The research results can provide reference for near early warning,disaster prevention and reduction of shortterm heavy precipitation in Chongqing.