PARENT SESSION
Poster Session 13: Landscape Ecology / Geomorphology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Calculating 150 years of land use change within a Midwestern watershed.
Retzlaff, William*,1, Ringhausen, Alley2, Hu, Shunfu1, Schaefer, Jake3, Satam, Neeta1, Bhattarai, Prajwol1, 1 Southern Illinois University Edwardsville, Edwardsville, IL2 Great Rivers Land Trust, Godfrey, IL3 University of Southern Mississippi, Hattiesburg, MS
ABSTRACT- The land area (31450 ha) within the Piasa Creek watershed in West Central Illinois has experienced extensive agriculturalization of the original prairie and mixed-forest regions over the last 150 years, and, more recently, increased urbanization. This watershed is unique in that it has been targeted by a non-profit organization, the Great Rivers Land Trust, for a reduction in stream sediment of 6600 tons annually. Because there is a significant positive relationship between land-use and sediment deposition in streams, rivers, and lakes that has been implicated in changes of fish diversity and water quality we have examined the history of land use change within this watershed. In order to quantify the land use change within this watershed, we have used GIS to calculate the land use at different times (based upon data availability) over the last 150 years. Tiff images of the federal land plats from the federal land survey 150 years ago in Illinois were used to reconstruct the pre-settlement land cover in the Piasa Creek watershed. The pre-settlement watershed was dominated by forest and prairies. More recent land use within the watershed was calculated in 1940 (aerial photographs), 1968 (aerial photographs), 1984 (LANDSAT TM image), 1998 (DOQQs), and 2002 (LANDSAT TM image). Currently, agricultural land use still dominates the watershed (greater than 65% of the land area), followed by forests, and urban/suburban land use. Recently, between 1983 and 2002, there has been a 6% decrease in agriculture land use, a regeneration of 4% of forest cover, and a 1% increase in urban/suburban land use within the watershed. Knowledge gained will help land managers make decisions regarding restoration within the watershed and, therefore, sediment reduction and water quality improvement.
Key words: watershed, land use, sediment