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Illinois State Water Survey Bulletin 75PDF


Title:Precipitation Frequency Study for Illinois
Author(s):Angel, James R.; Markus, Momcilo; Wang, Kexuan Ariel; Kerschner, Brian M.; Singh, Shailendra
Geographic Coverage:Illinois
Issue Date:2020-03
Publisher:Illinois State Water Survey
Citation Info:Angel, J. R., M. Markus, K. A. Wang, B. M. Kerschner, S. Singh. 2020. Precipitation Frequency Study for Illinois. Illinois State Water Survey Bulletin 75, Champaign, IL.
Series/Report:Bulletin (Illinois State Water Survey) no. 75
Genre:Technical Report
Description:Storm frequency estimates and their temporal distributions are important in determining estimates of runoff or peak flow rates in many engineering and hydrological problems. Illinois State Water Survey (ISWS) Bulletin 70 (Huff and Angel, 1989a) has been serving as the design rainfall standard in Illinois since its publication in 1989 (IDOT, 2011). In addition, Illinois state agencies adopted ISWS Circular 172 (Huff and Angel, 1989b) and ISWS Circular 173 (Huff, 1990). Circular 172 provided some updates to Bulletin 70, and Circular 173 provided standard temporal distributions of rainfall events, known as Huff curves. These standards are best described in Circular 173, “This document provides the best available information on the time-distribution characteristics of heavy rainstorms at a point and on small basins encompassing areas of up to 400 square miles in Illinois and the Midwest. It is recommended for use in conjunction with Illinois State Water Survey Bulletin 70 (Huff and Angel, 1989a) and Circular 172 (Huff and Angel, 1989b) for runoff computations related to the design and operation of runoff control structures.” Although Bulletin 70, Circular 172, and Circular 173 represented the best available data at the time of their publication, they needed to be reevaluated and updated after more than three decades of using these standards. An additional 34 years of monitoring data has become available, and the growing evidence of the nonstationary nature of heavy precipitation events indicated that more frequent evaluations of precipitation frequency estimates are needed to capture changes in heavy precipitation (Winters et al., 2015). This report provides new, updated precipitation frequencies for 10 regions in Illinois for event durations ranging from 5 minutes to 10 days (240 hours) and for recurrence intervals ranging from 2 months to 500 years. New, updated time-distribution characteristics of rainfall events, known as “Huff curves,” are also provided. The precipitation frequency estimates and their time distributions presented in this bulletin supersede those published in Bulletin 70, Circular 172, and Circular 173.
Date Available in IDEALS:2020-03-31

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