ANALYSIS OF BEDLOAD SEDIMENT AND THE EFFECT OF FLOODING ON BEDLOAD SEDIMENT TRANSPORT OF SALT CREEK, IN NORTHWESTERN ILLINOIS

Salt Creek is a tributary of the Des Plaines River in northeast Illinois that formed about 14,000 years ago. It flows through the area containing the Tinley ground and end moraines, the Valparaiso ground moraine, and a glacial lake bottom. The till is of the Late Wisconsinan Wedron Group. Beneath the glacial deposits lies Silurian-aged dolomite of the Racine Formation. The Salt Creek floodplain, which lies within the Chicagoland area, has been extensively developed over the past 30 years, and as a result is prone to flooding. Interpretations of peak annual flow graphs for three USGS gauging stations along Salt Creek indicate a trend of increasing peak discharge over the past 30 years. The threat of floods along Salt Creek initiated a Watershed Work Plan in the early 1970's, which included the construction of a dam and five storm detention basins in its upper floodplain. Since 1999, roughly 25 more acres of land were acquired by the Cook and DuPage County Forest Preserve Districts to protect the floodplain from further development. The focus of this study is two-pronged: 1) to describe the downstream variations of the bedload sediment in Salt Creek (grain size, shape, and lithology) and 2) to calculate the effects of increased and more frequent flooding on bedload sediment transport.