基于特征分析的设计降雨过程分析与计算

Analysis and Calculation of Design Rainfall Process Based on Characteristic Analysis

设计降雨是工程水文计算的重要内容.为提高设计降雨的客观性及工程水文计算的区域适用性,选取河北省永年站1980-2018年逐小时降雨观测数据为研究数据,在分析其降雨年际、年内分布特征的基础上,以降雨量、降雨峰值、降雨历时、峰值比四个特征作为关键要素,采用以降雨量和降雨历时为变量的排频法,分别对永年站汛期、非汛期的典型降雨过程进行设计和分析.结果表明:永年站近39年降雨过程具有明显的丰平枯交替变化特征;汛期典型降雨过程的降雨量为16.5 mm、降雨峰值为6.2 mm、降雨历时为3 h、雨型为单峰靠后;非汛期典型降雨过程的降雨量为15.9 mm、降雨峰值为2.6 mm、降雨历时为10 h、雨型为单峰居中;汛期设计降雨过程具有历时短、峰值大、变化急且降雨量集中于后部的特点;非汛期设计降雨过程具有历时长、峰值小、变化缓且降雨量主要集中在中后部的特点.不同时期特点迥异的设计降雨过程较好地反映了区域降雨的时程特征,可为城市防洪排涝的计算、科学灌溉制度的制定提供参考.

Design rainfall is an important content of hydrological calculation. In order to reflect the authentic rainfall and improve the applicability of hydrologic calculation,the artificial rainfall process based on the regional characteristics was designed. The hourly measured rainfall data of Yongnian Station in Hebei Province from 1980 to2018 was selected as the research data,and the inter-annual and intra-annual distribution characteristics of rainfall were analyzed. Based on the above analysis,the four characteristics of rainfall,rainfall peak,rainfall duration and peak ratio were selected as the calculating elements,and the frequency analysis method with rainfall and rainfall duration as variables was applied to design and analyze the typical artificial rainfall processes in flood season and non-flood season of Yongnian Station. The results indicate that the rainfall process of Yongnian Station in recent 39 years has obvious characteristics of alternating changes of wet,normal and dry years. The rainfall,rainfall peak and rainfall duration of the typical rainfall process in flood season are 16.5 mm,6.2 mm and 3 h respectively,and the rain pattern of this process is a back single peak. The rainfall,rainfall peak and rainfall duration of the typical rainfall process in non-flood season are 15.9 mm,2.6 mm,and 10 h respectively,and the rain pattern of this process is a single center peak. The designed rainfall process in flood season has the characteristics of short duration,large peak value,rapid change and rainfall concentrated in the rear part. The designed rainfall process in non-flood season has the characteristics of long duration,small peak value,slow change and rainfall mainly concentrated in the middle and rear parts. The design rainfall processes with different characteristics in different periods can better reflect the actual characteristics of regional rainfall. The research can provide a reference for the calculation of urban flood control and drainage and the formulation of scientific irrigation system.