【Daily Question】Utilities - Water Supply and Drainage - 20200227

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Which of the following statements regarding the selection of design parameters for roof rainwater drainage systems does not conform to the current \"Code for Design of Building Water Supply and Drainage\"? (   )   A. The design rainfall intensity is calculated using the local storm intensity formula. B. The design rainfall duration is taken as 5 minutes. C. For the roofs of general buildings, the design return period is selected to be between 2 and 5 years. D. The impact of the runoff coefficient on the design flow rate is not considered. Answer: D. Options A, B, and C respectively conform to Article 4.9.3, Paragraph 1 of Article 4.9.4, and Table 4.9.5 of the current “Code for Design of Building Water Supply and Drainage”. Option D does not comply with the provisions of Article 4.9.2 and Table 4.9.5 in Article 4.9.6 of the current \"Code for Design of Building Water Supply and Drainage Systems\". The influence of the runoff coefficient should be taken into account in the design flow rate of the roof rainwater drainage system. This runoff coefficient shall be set at 0.9.