城市暴雨公式样本不同采样方法的偏差及处理方法

Discussion on Bias of Different Sampling Methods and Processing Approaches for Urban Rainstorm Formula

2004年以来,我国气象部门大部分站点普遍采用精度为0.1或0.2 mm的翻斗式雨量器,而水文部门相继在2010年普及精度为0.5 mm的翻斗式雨量器,国家级站点基本同时保留国际通行的虹吸式雨量器进行辅助校验。样本采集均按5 min的时长读取降雨过程,滑动截取5min数据统计各指定历时年最大值,公布于《水文年鉴》。基于水文部门公布的《水文年鉴》或气象部门整编的不同时长滑动样本,选择典型雨型、暴雨强度及降雨变化过程,比较不同滑动时长样本得出,各指定历时样本存在一定的差率;通过比较不同滑动时长暴雨强度得出,随着降雨历时及重现期的不断增大,雨强差率变小,逐渐接近实际值;采取插值法在保证暴雨样本统计精度的同时,可大大提高排水设计的精度。

Since the year of 2004, most of observation sites from meteorological department in China adopted tipping bucket rain gauge, whose measurement precision was 0.1 mm or 0.2 mm. In 2010, the instrument with the precision of 0.5 mm was widely used in hydrological department. Furthermore, state-run observation sites adopted the siphon rain gauge to carry out the assistant test. The amount of rainfall during the 5-min period was collected as the samples. Maximum values of specified rainfall durations based on the sliding intercepted during the whole 5 minutes are published in the Hydrological Year Book. According to the samples from the Hydrological Year Book and other meteorological departments, typical rainfall patterns, rainstorm intensity and precipitation alteration process were selected. Results showed that by comparing the samples of different sliding durations, each sample of specified duration had a certain margin. By comparing the rainstorm intensity of different sliding durations, rainstorm intensity margin became much smaller when the duration and reoccurrence expended, which was also much closer to the true value. Results also showed that interpolation would enhance the statistical precision of sampling as well as the design precision of urban water drainage.