Spatial and temporal changes of extreme precipitation events (EPE) in the Southeastern United States

Keywords: extreme precipitation events, Southeastern United States, Mann Kendall tests
Abstract Type: Poster Abstract

Abstract

The Southeastern United States (hereafter SeUS) is defined as nine adjacent states in this research (see Figure 3). Extreme Precipitation Events (EPE) are the result of intense rainfall rates over short time periods, which often produce flash flooding. The damage associated with EPE and flash floods is significant because these events are hard to predict and give less time to prepare. EPE is defined in this research as ≥1 in. h-1 occurring over less than or equal to 5 hours across the SeUS. Archived hourly precipitation data were collected from NCDC for the SeUS stations with at least temporal coverage of 40 years or more and missing data of less than 5 percent. Mann-Whitney U tests were employed to understand the changes in cumulative density function (CDF) of EPE frequency in the study area for 1981-2000 and 2001-2020. The test result revealed that the population of the two time periods has a significant difference. Non-parametric Mann-Kendall tests were chosen to detect monotonic trends in the EPE frequency time series for SeUS. Findings indicate that 20 stations out of 61 stations observed a significant (at 0.05 level) increasing trend while no station observed a significant decreasing trend. The Pettit test indicates that out of 61 stations, 15 stations had the presence of significant change points in the time series. The Mann-Kendall test was also employed to the temporal distance between EPE, results revealed that 17 stations out of 61 stations observed a significant decreasing trend.