吉林市暴雨强度公式推求和设计雨型

Rainstorm Intensity Formula and Design Rainstorm Pattern for Jilin City

利用吉林市1961—2017年分钟降雨量数据,分别采用年最大值法和年多个样法选样,P-Ⅲ型、指数型和Gumbel分布拟合频率分布曲线,根据误差最小原则选择最佳取样及拟合方法,采用最小二乘法求解暴雨强度公式参数,并将新旧暴雨强度公式进行比较,再利用推求出的公式参数模拟吉林市短历时芝加哥雨型。结果表明:通过年最大值法选样和P-Ⅲ型频率分布曲线拟合得到的暴雨强度公式精度最高。5~20 min历时新编暴雨强度公式计算的暴雨强度值与旧编公式相当或偏小,30~180 min历时新编暴雨强度公式计算的暴雨强度值偏大。在相同重现期下,随着降雨历时的延长,雨强变化率逐渐加大。吉林市短历时雨型的综合雨峰位置系数为0.389。30~180 min历时雨型形态均为单峰型,各历时瞬时雨强峰值接近,雨峰位置位于偏整场降雨过程的1/2处之前。累计雨量的变化特征与设计暴雨雨型形态一致。

Based on minutely precipitation data from 1961 to 2017 in Jilin City,rainstorm data were sampled using the annual maximum method and the annual multi-sampling method,and frequency distribution curves were fitted by P-Ⅲdistribution,exponential distribution and Gumbel distribution,respectively.The rainstorm intensity formulas were solved by least square method,and the fitting methods were optimized according to the principle of the minimum errors.The new rainstorm intensity formula selected was compared with the rainstorm intensity formula used currently.The design rainstorm pattern was studied by Chicago method on these basis.The results show that the formula fitting precision was higher using the annual maximum method and P-Ⅲdistribution.The rainfall intensities calculated by the new formula in durations from 5 to 20 minutes under each return period were smaller than those calculated by using the old rainstorm intensity formula or basically equivalent to those.The rainfall intensities calculated by the new formula in durations from 30 to 180 minutes under each return period were mainly lager than those calculated by the old formula.In the same return period,the rainfall intensity change rate was getting larger with the extension of rainfall duration.The comprehensive coefficient of rainfall peak position was 0.389.All the design rainstorm patterns were the single peak in durations from 30 to 180 minutes,and the rainfall peak intensities were similar.All the rainfall peak positions were located before half of the rainfall duration.The accumulation precipitation presented the same variation characteristics with the design rainstorm pattern.