Watershed Assessment for Ecosystem Restoration

Scientists collecting soil samples from Big Ditch watershed. Photos by Don Keefer.

An ISGS team is participating with the Illinois State Water Survey (ISWS) and the Illinois Natural History Survey (INHS) in assessments of Illinois River basin subwatersheds for ecosystem restoration opportunities. The assessments were requested by the Illinois Department of Natural Resources (IDNR to support the Illinois River Basin Comprehensive Plan written by the U.S. Army Corps of Engineers, Rock Island District in partnership with IDNR. The Illinois River basin drains nearly half of the state, contains or receives the wastewater from most of the population of the state, and is a nationally significant passageway for migratory birds. Despite significant ecological degradation over the past two centuries, the river was identified by the National Research Council as one of three large floodplain river systems in the lower 48 states with the potential to be restored to anapproximation of its outstanding biological past. The current focus of watershed assessment is on direct tributaries to Peoria Pool. The goal is to identify projects to reduce sediment loading to the Illinois River.

The watershed assessments are intended to be rapid (about 1year), and lead to identification of critical restoration areas. The compendium of data will also constitute baseline information for the long-term monitoring of watershed condition and project success. ISGS is providing a geological perspective by

  • analyzing stream channel planform change by comparing historic and recent aerial photographs to identify styles and locations of channel change, to identify fundamental processes, and to make preliminary links between landscape change and channel change;
  • mapping surficial geology to identify sediment sources, materials properties, and long-term geomorphic evolution of the watersheds;
  • compiling comprehensive, interdisciplinary, existing data into watershed-focused databases. Each database is shared with ISWS and INHS partners and analyzed by ISGS for existing watershed conditions and changes in land cover and land use; and
  • contributing to analysis of channel geomorphic measures and aerial (helicopter) video imagery obtained by ISWS.

The ISGS team is just starting a dendrochronologic analysis of gully formation in Partridge Creek. The analysis could be an important contribution to interpretation of post-glacial landscape evolution in west-central Illinois. The age of trees and their growth history could provide information on geomorphic processes and variations of recent climate.