Channelization effects on floodplain functions in western Tennessee

We examined six river reaches in western Tennessee over a two-year period to determine how channel alteration affected floodplain hydrology and nutrient pools. Four sites, two depression and two non-depression, were established on the floodplains of each river, and data on vegetation, water table depth, redox potential, and soil and leaf nutrient pools were collected. Channelized streams had higher mean water tables and lower soil redox potentials than non-channelized or channelized and leveed streams. Leveed systems appeared to have mostly oxidized soil conditions, similar to uplands. Leaf and soil nutrient pools were generally higher in non-depression sites, especially for channelized streams. A drought between the first and second years of sampling rendered very different results between the two sampling occasions. Following the drying of the floodplain, nutrient pools were not significantly different between depression and nondepression sites. These results underscore the need for a better understanding of the relationships among channel modifications, floodplain hydrology, vegetation, and nutrient cycling.