STREAM-CHANNEL MORPHOLOGY IN A MIXED-BEDROCK VALLEY: THE HARPETH RIVER WATERSHED, MIDDLE TENNESSEE

Numerous watershed attributes, such as lithology, tectonics and climate, have been identified as potential controls on fluvial system morphology and behavior. The relative roles and interactions of these attributes in defining landscape erosion and evolution remain an important area of research. Here, we use digital elevation models to examine the differences in river channel morphology expressed within the Harpeth River Watershed that crosses the Paleozoic carbonate bedrock of the Nashville Basin and the Western Highland Rim. The long profiles of the major tributaries of the Harpeth River and the trunk stream were extracted and elevation versus the spatial integral of the drainage area (chi) plotted. The resulting chi plots capture the differences in channel morphology between the Central Basin and the Western Highland Rim. Tributaries draining the Central Basin exhibit similar profile concavity within the uncertainty which is higher than the concavities of the tributaries draining the Western Highland Rim. These data also support the field observations of increased sinuosity and well-developed terraces documented in the Western Highland Rim channels suggesting a link between changes in bedrock lithology and stream morphology across the different carbonate bedrock formations.