Streambank erosion in two watersheds of the Central Claypan Region of Missouri, United States

Abstract

This study was undertaken to assess the importance of streambank erosion to the total in-stream sediment of two agricultural watersheds within the Central Claypan Areas. The objective of this research was to determine the effect of stream order, adjacent land use, and season on streambank erosion rates. Thirty-four study sites were established in 2007 and 2008 within Crooked and Otter Creek watersheds, two claypan watersheds located in northeastern Missouri. At each site, field assessments of severely to very severely eroding bank length were determined along 300 to 400 m (984 to 1,312 ft) stream reaches. A factorial experimental design was implemented with four land uses (crop, forest, pasture, and riparian forest), three seasons, and three stream orders (1st, 2nd, and 3rd). Each treatment was replicated three times for each stream order, except for the cropped 3rd order treatment as only one suitable treatment site could be found. Streambank erosion was measured using erosion pins, which were installed in randomly assigned plots that included at least 20% of the eroded bank length within each site. The effect of different seasons was assessed by measuring the length of the exposed pins three times per year (March, July, and November). The bulk density and carbon and nitrogen content of bank material were also determined. Sediment loss rates showed that season and the three-way interaction between season, land use, and stream order were highly significant. Erosion rates were consistently higher in the winter months than spring/ summer and fall seasons; however, the significant three-way interaction precluded a simple interpretation of the seasonal effect. Soil nutrient concentration data showed that forest sites had significantly lower C and N concentrations than other land uses. At the watershed scale, bank sediment accounted for 79% to 96% of the total in-stream sediment and 21% to 24% of the total N exported from the study area. These results indicate that streambanks are the dominant source of sediment and a significant source of N in these streams. Therefore, improved management of riparian areas to decrease streambank erosion would result in significant water quality improvement in streams of the Central Claypan Areas in northeastern Missouri. (1996) reported that streambank erosion accounted for up to 80% of the in-stream sediment. Recent work utilizing stable isotopes has shown that streambank erosion can account for the majority of suspended sediment present in streams during high flow conditions (Wilson et al. 2008). In addition, streambank erosion is an important source of nitrogen (N) and phosphorus (P) contamination in streams (DeWolfe et al. 2004;Zaimes et al. 2008). State and federal conservation agencies acknowledge both the impact of sediment and associated nutrients on aquatic habitats (Shields et al. 1994) and the implications of soil loss on agricultural productivity.Due to the runoff-prone nature of claypan soils, overland erosion from cropped fields has been widely assumed to b...

Human amplified changes in precipitation-runoff patterns in large river basins of the Midwestern United States

“…Bank erosion is a significant sediment source in many alluvial rivers, contributing as much as 80% to 96% of the sediment that comprise a river's total sediment load (Belmont et al, 2014;Kronvang et al, 2013;Palmer et al, 2014;Schaffrath et al, 2015;Simon et al, 1996;Stout et al, 2014;Willett et al, 2012). For some agricultural basins, erosion of near-channel sources contributes more fine sediment than does agricultural field erosion (Belmont et al, 2011;Lenhart et al, 2012;Trimble, 1999).…”

Fine sediment sources in Conservation Effects Assessment Project watersheds

“…The channel contributions determined by Grissinger et al (1991) and Kuhnle et al (1996) were in the range of bank sediment contributions to Goodwin Creek determined using the method described herein (61% to 85%). Willett et al (2012) calculated that an average of 88% of the sediment from two watersheds in the claypan region of Missouri originated from channel sources. The channel bank erosion rates were calculated from quarterly measurements of bank erosion rates from more than 3,000 erosion pins and a survey to determine the fraction of stable and unstable banks in the watersheds.…”

Human amplified changes in precipitation–runoff patterns in large river basins of the Midwestern United States

“…Sediment sources derived from near or within the channel itself (e.g., bank erosion from channel widening) are particularly sensitive to changes in streamflows (Lauer et al, 2017;Schottler et al, 2014;Lenhart et al, 2013). Bank erosion is a significant sediment source in many alluvial rivers, contributing as much as 80 to 96 % of the sediment that comprises a river's total sediment load (Kronvang et al, 2013;Palmer et al, 2014;Schaffrath et al, 2015;Simon et al, 1996;Stout et al, 2014;Willett et al, 2012). For some agricultural basins, erosion of near-channel sources contributes more fine sediment than does agricultural field erosion Lenhart et al, 2012;Trimble, 1999).…”