Abstract:

Based on hourly precipitation data from conventional weather stations and regional automatic stations over Haihe River basin in flood season from 2011 to 2013, a set of new rainfall data with high network density was generated and this new data is from synthetic weather stations. Effects of station density under different topography on accuracy of area rainfall were analyzed by using area rainfall dispersion coefficient and its ratio coefficient as well as relationship between point rainfall and area rainfall. The results show that station density is an important factor which affects accuracy of area rainfall, and it has different effects on area rainfall under different topography. In water system of mixed topography such as Luan River basin, topography and precipitation are complex, so effect of station density is also the most significant. Area rainfall is overestimated about 2.5 mm using lower density data from conventional weather stations compared with using higher density data from synthetic weather stations, and 12% errors exceed 5 mm. In water system of mountain area topography such as Yongding River, it is more than 1.5 mm, and relative errors reach 80.3%, especially during local short-time precipitation, errors of area rainfall is ten times as large as the true value. Additionally, station density has lower impact in mixed topography such as Beisan River, Nanyunhe River than in Luanhe River, so is in Tuhaimajia River of plain area, and the area with small difference of topography such as Daqinghe River and Ziyahe River.

Key words: Deviation coefficient of area rainfall, Relationship between station rainfall and area rainfall, Thiessen polygons, Station density