北京城市和郊区夏季降雨日变化特征及对排水设计的影响分析

Diurnal Variations of Summer Precipitation in Urban and Suburb and Influence on Drainage Design in Beijing

分别选取观象台和密云站作为北京市城区及郊区代表站,应用两站1961—2013年逐分钟雨量观测资料,比较北京城区和郊区夏季降雨量、降雨频次及降雨强度的日变化特征,利用耿贝尔分布拟合的年最大值法推求城区和郊区暴雨强度公式,比较其空间适用性。结果表明,北京地区降雨具有明显的日变化特征:城市和郊区的夜雨比重均大于日雨,降雨量、频次、降雨强度午后至次日清晨为高值区;郊区夏季降雨总量、短历时降雨和降雨雨强均比城区偏大。暴雨强度公式计算结果表明应用城区一站的降雨资料计算得出的公式在全市并不适用,在市政排水设计时应考虑城郊差异,采用不同的标准。

The rainfall data from the Beijing Meteorological Observatory and Miyun Station in Beijing,which were assumed as representative stations for urban and suburban areas,are used.Based on the minute-to-minute rainfall observation data from 1961 to 2013,comparison and analysis are made of the different cumulative rainfall in summer,the frequency of rainfall,and the precipitation intensity between urban and suburb areas.Also,using the Gumbel method,which can fit annual maximum to derive the equations of rainstorm intensity for urban and suburb areas,their spatial availabilities are compared.The results indicate that there are obvious characteristics in variations of daily rainfall in Beijing,including the larger proportion of rainfall at night and higher occurrence frequency of rainfall from noon to midnight and greater rainfall amount,frequency,and precipitation intensity during 15：00to 17：00in both urban and suburb areas;the total rainfall,short-duration rainfall,and precipitation intensity in summer were greater in the suburb area.However,the intensity-duration-frequency curve shows that the rainfall data of urban stations is inapplicable for suburban stations,and the difference between urban suburb areas should be considered.Different standards should be adopted in the design of the drainage system.