Rahmani 2015

Changes in the Extreme Rainfall Events Trends and Variability in Kansas, USA

Vahid Rahmani*, Stacy L. Hutchinson, John A. Harrington, Jr., J. M. Shawn Hutchinson

*Corresponding author at: Kansas Biological Survey, The University of Kansas, Lawrence, KS 66047, e-mail: vrahmani@ku.edu

 Heavy rainfall event magnitude and distribution are expected to change with the changing climate in Kansas. Investigating trends of intense rainfall events provides important information for improved water management decisions. The daily rainfall data from 1890 to 2012 were analyzed for 23 stations in Kansas for annual daily maximum, upper 1%, 5%, and 10% of daily rainfall. Increasing trends were found at the majority of stations for all parameters since 1890. The daily annual maximum ranged from 129 mm (Saint Francis) in the northwest to 356 mm (Fort Scott) in the southeast with the slowest increase of 0.05 mm/10yr (Elkhart) in the southwest and the greatest increase of 4.2 mm/10yr (Independence) in the southeast. In general, eastern Kansas exhibited a higher increasing trend for the daily annual maximum rain. The monthly annual maximum ranged from 291 mm (Lakin) in the west to 626 mm (Horton) in the northeast, both in June. In addition to the entire period (1890–2012), four consecutive periods, 1891–1920, 1921–1950, 1951–1980, and 1981–2010, were selected to analyze the variability of extremes over time. The trend and variability of heavy rainfall events over the subperiods did not match the entire period, further supporting the high variability in the region. The analysis showed that the daily heavy rainfall event patterns are changing, especially in the recent years (1980–2010). The results are useful for updating hydrologic structural designs and water management techniques which impact agricultural production, society, and economy.