GEOMORPHOLOGICAL CHANGES TO THE LITTLE WABASH RIVER THROUGHOUT ALMOST EIGHT DECADES

Geologically-speaking, rivers are extremely dynamic, cutting back and forth and inscribing their channel paths into the sediments, constantly reshaping the landscapes in which the rivers course. Local studies of individual rivers or stream reaches have been examined in relation to groundwater supply (VanLooy, 2005), endangered species habitat (Greco and Plant, 2003), and channelization processes in agricultural watersheds (Urban and Rhoads, 2003). The Little Wabash River in south-central Illinois has been the focus of recent work to find how the channel’s path has evolved over several decades (LaVeau et al., 2014, Burns and Viertel, 2011) in Effingham and Clay Counties, IL. This study takes the project forward, examining the channel’s migration through time in Wayne County. Special attention is given to the impact of channel changes on agricultural acreage.

The Little Wabash is a meandering river whose headwaters originate in southwestern Coles County and flows around 200 miles southward to its confluence with the Wabash River. The river winds across different property parcels, some having different owners on either side of the river. Therefore, any change in the stream’s path creates a loss or gain of acreage. This project’s goal was to investigate changes to the acreages found along the Little Wabash River in Wayne County. The County’s dominant land use is agricultural in nature, with crops of soybeans, corn, wheat, winter wheat and forage-land –listed in respective order of greatest to least in production acres. The yields from Wayne County are representative of the average cropland and yields throughout Illinois’ counties. For example, soybeans yielded around 4,795,000 bushels. This yield along with the other crops equated to over 126 million dollars of gross revenue in 2011 alone (TopCounty SoyIllinois, 2011).

The historical channel of the river was digitized to establish a baseline survey using archival aerial photography acquired in 1938, which were georegistered to their proper locations and proportions. Current channel position was acquired through a basemap within the GIS ArcMap software and then digitized in a similar manner as the 1938 data. The comparison between the datasets highlights the alterations that have occurred along the Little Wabash River’s path over the last 75 years in Wayne County.