Evaluation of Antecedent Storm Event Characteristics for Different Climatic Regions based on Interevent Time Definition (IETD)

Inter-event Time Definition (i.e., minimum dry period between storm events, or IETD) is a very crucial parameter that is often neglected in the analysis of rainfall time series. Based on an IETD, a long-term rainfall record can be analyzed for different storm event characteristics such as rainfall event volume, duration, intensity and inter-event time. The design storms adopted considering IETD can influence the stormwater storage decisions within urban watersheds. Moreover, current interests in the low impact development (LID) require careful analysis of rainfall and runoff volume in the analysis and design of best management practices. The current study proposes an investigative study of antecedent storm event characteristics for different climatic regions within the United States based on varying values of IETD. In this paper, the focus is placed on analyzing the long-term rainfall record to assist in the better quantification of the characteristics of catchment conditions antecedent of a design storm. The design storm might be applied for the design of stormwater management facilities. More specifically, this research aims at the evaluation of the probabilistic characteristics of the total volume of precipitation that has occurred over a time period preceding a runoff-producing event.