Sediment load during flood events for Illinois stream Demissie, M. 1995. Sediment load during flood events for Illinois streams. Pages 341-357 in the Proceedings of the International Joint Seminar on Reduction of Natural and Environmental Disasters in Water Environment, Seoul National University, Seoul, Korea, July 18- 21, 1995. Reprinted by the National Biological Service, Environmental Management Technical Center, Onalaska, Wisconsin, August 1995. LTRMP 95-R006. 17 pp. (NTIS #PB95-267423) ABSTRACT A large percentage of the annual sediment yield from a watershed is transported by a stream during a small number of floods that occur in a relatively short period of time in a year. The sediment load during flood events are examined and relations between the annual sediment yield and the sediment load during the major floods in a given year are developed based on available stream sediment data from the state of Illinois. On the average, the annual flood transports from 20 percent (for large rivers) to 23 percent (for small streams) of the annual sediment load, while the two highest floods in a year transport from 32 to 43 percent of the annual sediment load. The average duration of the annual flood is only 9.2 days which is 2.5 percent of the whole year. The average duration of the two highest floods is 17 days which represents only 4.7 percent of time in a year. KEYWORDS sediment, sediment yield, annual sediment load, streams, floods, rivers