A review on recent advances of urban rainfall intensity-duration-frequency relationships

Urban rainfall intensity-duration-frequency (IDF) relationships, capable of reflecting urban rainfall characteristics, are an important premise for the planning and design of the infrastructure and sponge city development. The paper briefly described the derivation process of IDF relationships and reviewed recent advances in several aspects including the form of IDF relationships, sampling methods of rainfall data, selection of frequency curves, parameter estimation of distribution functions, and parameter determination of IDF relationships. We analyzed and summarized advantages and disadvantages of the methods reviewed, and pointed out issues associated with two-step optimization and one-step optimization during the IDF relationship establishment, the phenomenon of equifinality in parameter fitting, the rationality analysis of equations and parameters, and the establishment of long-duration IDF relationships. In conclusion, we emphasized that further research is needed in the comprehensive error analysis, rationality analysis, spatial rainfall distribution, and influences of climate change on future rainfall.