Study on long duration comprehensive rainstorm formula based on rainstorm attenuation characteristics in Shanghai

The comprehensive rainstorm formula applicable to different durations is an important basis for coordinating urban pipe network drainage and regional flood and waterlogging control. The 65-year monitored rainfall series of Xujiahui meteorological station, which was selected to be the representative rain station of Shanghai City, was collected to establish the relationship between rainstorm intensity and duration in different return periods. The rainstorm attenuation characteristics was revealed to formulate the single rainstorm formula of each return period. The long duration comprehensive rainstorm formula applicable to different return periods was explored with reference to the rain force formula, and the rainfall return period formula was derived. Results show that the rainstorm intensity attenuation index between 1 hour and 24 hours in different return periods are approximately 0.74. The obtained long duration comprehensive rainstorm formula could be used to calculate the design storm of any duration (1-24 hours) and any return period (2-100 years), and the relative and absolute root mean square error of the formula are 1.9% and 0.009 mm/min, which meet the requirements of the criterion, respectively. Also, the rainfall return period formula could be applied to ascertain the return period of any rainfall event between 1 hour and 24 hours so as to serve urban flood prevention and control decision making effectively. Notably, the research achievements have been incorporated into the local standards of waterlogging control in Shanghai City and are of significant reference value to other cities.