CHANNEL PLANFORM, GEOMETRY, AND BIOTIC FACTORS OF AN IRREGULAR STREAM IN AN APPALACHIAN MOUNTAIN WETLAND

Streams of southern Appalachian Mountain wetlands display unique morphological conditions and provide a range of ecologic and hydrologic services, yet they have received very limited attention in the scientific literature. The objectives of this study were to 1) quantify the complexity of channel planform, 2) measure channel geometry in straight channel sections and bends, and 3) evaluate channel features in association with potential biotic controls of the Cranberry River as it flows through a southern Appalachian wetland. The Cranberry River displays an irregular planform, which is characteristic of wetland streams, as it meanders through a peatland complex located in the highlands of West Virginia. A numerical model was applied to a 3.2 km section of the Cranberry River to measure quantitative channel sinuosity in relation to scale and field data were collected from 48 cross-sections to evaluate channel geometry in regard to biotic factors (vegetation, beaver dams, channel wood). The results revealed that channel planform is quantitatively complex at channel lengths less than 100 m and greater than about 1 km. The channel was mostly comprised of clay and silt, and formed roughly rectangular cross-sectional shape. Straight channel sections averaged wider wet channel width (5.0 m) than bends (4.1 m) and both averaged a thalweg depth of 0.5 m. Biotic factors of vegetation, beaver dams, and channel wood did not appear to have significant influence on channel form. The riparian area consisted predominantly of thick Alnus rugosa thickets and only two locations had any vegetation within the channel itself. Beaver dams appeared to have only limited influence on channel form and very few pieces of wood were found within the channel. These findings are intriguing because irregular channel form of wetland streams is often attributed to biotic factors, but the Cranberry River displays complex planform without the apparent influence of vegetation or other biological controls.