Riparian vegetation as an indicator of channel widening and bank-slope development on modified West Tennessee streams

Most streams in West Tennessee have been straightened and dredged for flood control. These modifications have initiated long-term changes in bed level and, in many cases, channel widening that occurs through fluvial erosion and mass wasting of banks. Plant-ecologic and tree-ring analyses of riparian vegetation yields information on dates and rates of bank failure, bank-sediment accretion or scour, and degree of bank-slope development. Dendrogeomorphic analyses indicate widening rates up to 2.4 meters per year along highly unstable reaches. Similarly, analyses of buried tree stems, on re-stabilizing banks, indicate average accretion rates of 5 to 7 centimeters per year. Presence of particular species may indicate trends of increasing or decreasing stability. The most common woody plants establishing on adjusting bank slopes include; black willow, boxelder, river birch, and sycamore. Banks largely devoid of establishing woody vegetation are characteristic of the most unstable reaches. The establishment of riparian vegetation promotes bank stability by ameliorating bank-erosional processes.