A Sediment Budget for Town Creek Watershed: Suspended Sediment Transport Rates Analysis

Ramirez-Avila, J. J., McAnally, W. H., Langendoen, E. J., & Ortega-Achury, S. L. (2010). A Sediment Budget for Town Creek Watershed: Suspended Sediment Transport Rates Analysis. Conference Proceedings. Las Vegas, NV: Joint Federal Interagency Conferences 2010.

Sediment loads from watersheds located in the Southeastern Plain Ecoregion can have contributions from stream channel degradation as large as 90%. Monitoring and modeling techniques to assess the contribution of channel sediment to overall sediment load are needed to determine the reductions necessary to meet water quality standards. A study is performed with the main objective to evaluate streambank erosion rates and generate empirical correlations for estimating streambank surface erosion involving physical and geomorphic variables influencing this process for streams in the Southeastern Plains Ecoregion in Mississippi. Focusing on the Town Creek watershed in this ecoregion the study used a combination of methods including field reconnaissance and detailed data collection, surveying, and channel modeling. Watershed characterization and preliminary reports showed increased rates of sediments emanating from the northern headwaters of the watershed. Incised streams with unstable active streambank profiles near agricultural lands and limited or no riparian vegetation are common in the northern headwaters. Streambank failure events tend to be periodic and mainly occur during runoff season. Channel morphology changes from incised V-shaped channels to wide U-shaped channels with an accompanying increase in riparian vegetation density along the middle 20-km of the principal channel. Streambank erosion pin data along the middle 20-km of the principal channel showed negative average erosion depths (i.e., deposition) at most of the erosion pin plots. Although, jet tests showed streambank soils to be highly erodible. Preliminary results of watershed characterization and field observation show that streambank erosion and deposition rates are largely seasonal and depend on channel morphology.