Influence of spatial variation in daily rainfall on volume capture of rainfall by source control facilities in China

In order to study the influences of rainfall characteristics on the effectiveness of total runoff capture in different regions of China, the study draws on the daily precipitation data of 186 meteorological stations over nearly three decades for spatial analysis and statistical calculation, obtaining the volume capture ratio of annual rainfall. The corresponding design rainfall depth and annual controlled rainfall on average are determined. Then, the relationship between annual ratio of total runoff capture in each city and annual average of controlled rainfall is used to divide China into nine types. The results show that the design rainfall depth in China has considerable geographical variation, with the standard deviation of Guangdong, Sichuan, Guangxi, Hebei, and Henan approximating 1.5 to 3 times the national average, and that it increases with the increase in volume capture ratio of annual rainfall. Meanwhile, the marked spatial variation of rainfall within the province has led to significant differences in effectiveness of runoff capture at the source. In southern China, runoff control mostly features "high volume and low ratio."In contrast, areas of "low volume and low ratio" are found in Gansu, Ningxia and other places; covering 9.44% of the area, they have precipitation characteristics unfavorable for source control facilities. The "high-volume and high-rate" areas most suitable for source control are located in Southwestern China, accounting for 3.80% of the area.