Channel and Vegetation Change on the Cimarron River, Southwestern Kansas, 1953–2001

Abstract

Little is known about historical channel change along rivers on the Great Plains of the United States. Focused on a 113 km reach of the Cimarron River, southwestern Kansas, this study revisits the site of Schumm and Lichty's (1963) work that documented channel changes between 1874 and 1960. Based on field and archival evidence from Seward and Morton Counties, Kansas, we find that channel narrowing, which began in the 1940s, continues to the present. Between 1953 and 2001, the mean channel width of the Cimarron River decreased by 114 m, or 75 percent, although channel narrowing and the expansion of riparian vegetation were more pronounced in some locations than in others. The channel changes and increase in riparian vegetation both appear to have been caused by a decrease in annual peak flows, which favored in-channel sedimentation and the expansion of riparian vegetation. The decrease in annual peak flows coincided with a reduction in the annual variation in moisture conditions, as measured by the Palmer Drought Severity Index. Agricultural practices and groundwater withdrawals have likely contributed to the decline in peak flows since 1970.