MAPPING LANDSCAPE CHANGE: AN HISTORIC AND BATHYMETRIC STUDY OF LAKE SEQUOYAH, WASHINGTON COUNTY, ARKANSAS

Lake Sequoyah is a 160 hectare impoundment on the White River (northwest Arkansas) constructed from 1959 to 1961. The lake is located upstream of Beaver Lake, the principal drinking-water reservoir for northwest Arkansas. The lake is presently owned and managed by the Department of Parks & Recreation of the City of Fayetteville, Arkansas and serves as a recreational fishing lake. In the 45 years since impoundment, no bathymetric surveys of the lake basin have been conducted. A Knudsen KEL 320 B/P dual frequency (28 and 200 kHz) echo sounder was used to produce a detailed map of Lake Sequoyah, and this map was compared to historic pre-impoundment aerial photographs and topographic maps to examine post-impoundment topographic changes due to sedimentation and erosion. In general, bathymetric measurements were congruous with pre-impoundment topography indicating relatively little sediment accumulation within the main body of Lake Sequoyah. However, substantial change in landscape morphology was observed downstream of the dam. These changes likely resulted from increased downstream scouring and erosion associated with alteration of local base-level and discharge through the spillway. Results of this study provide insight into anthropogenic influences on regional waterways and a baseline for future monitoring of ongoing landscape change due to rapid population growth and increasing development.