Required number of years of rainfall data to determine the design rainfall depth of source control in sponge city construction
2022
Zhang, Zhiming | Liu, Di | Fang, Xing | Zhang, Rui | Wang, Wenliang | Li, Junqi | Ma, Shengfeng
Study Region: China Study Focus: In sponge city construction in China, rainfall data is the key to determining the rainwater source control scale. However, changes in rainfall characteristics can reduce the representativeness of the data. To obtain stable volume capture ratios (VCRs) of the annual rainfall through as little rainfall data as possible, this paper compares daily rainfall data from 159 cities in China in recent decades and finds the minimum number of years required to maintain stable VCRs under different design rainfalls. Finally, it gives the recommended observation periods (OPs) for different regions. New Hydrological Insights for the Region: For the last 35 years, the variation of daily rainfall in 75% of cities in China has been less than 0.66 mm, and the variation of skewness is less than 0.62. In general, the longer the observation period, the smaller the calculated VCR anomaly value and variation gradient will be. About 10% of cities cannot achieve stable VCRs by increasing the number of years of data. The denser urban distributed area needs larger OPs to determine the stable VCR; with the increase in design rainfall, the required OPs will also be lowered; in most cities, the VCR calculation does not require 30 years of rainfall data.
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