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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #331923
Title: Factors controlling streambank erosion and phosphorus loss in claypan watersheds

Author
item PEACHER, RACHEL - Farmer
item Lerch, Robert
item SHULTZ, R - Iowa State University
item WILLETT, CAMMY - University Of Arkansas
item ISENHART, THOMAS - Iowa State University

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2017
Publication Date: 3/1/2018
Citation: Peacher, R.D., Lerch, R.N., Shultz, R.C., Willett, C.D., Isenhart, T.M. 2018. Factors controlling streambank erosion and phosphorus loss in claypan watersheds. Journal of Soil and Water Conservation Society. 73(2):189-199. doi:10.2489/jswc.73.2.189.
DOI: https://doi.org/10.2489/jswc.73.2.189

Interpretive Summary: Eroding streambanks can be major sources of sediment and nutrients to streams and rivers, but no research on streambank erosion had previously been conducted in the northern Missouri region. This study investigated the effect of adjacent land use, stream order (i.e., channel size), and season of the year on streambank erosion and phosphorus (P) transport in the Central Claypan Region of northeast Missouri. Streambank erosion was measured at 37 sites in Crooked and Otter Creek watersheds from 2008 to 2011. At 18 of the sites, riparian vegetation data were collected and upstream watershed characteristics (e.g., drainage area, land uses, average slope) acquired. Overall, eroding banks accounted for an average of 53% of the total bank length across the sites. Season was the only important factor, with much greater soil loss occurring during the winter months while land use and stream order were not important factors. Watershed scale estimates showed that streambanks contributed an average of 83% of the stream sediment and accounted for 57% of the total P exported from the two watersheds. These results, along with earlier work showing that streambanks contributed 23% of the total nitrogen exported, clearly demonstrating the impact that bank erosion has on stream water quality in this region. Riparian vegetation and watershed characteristics were shown to be poorly correlated to bank erosion. Thus, existing land uses, bank vegetation, stream order, and watershed characteristics were not the primary factors controlling streambank erosion rates. Other factors, such as historic land use changes, stream channelization, and the damming of the Salt River have resulted in major alterations to stream hydrology and geomorphology in these watersheds. These over-arching factors, in combination with season, continue to be the main factors controlling streambank erosion in these watersheds. Farmers and land managers will benefit from this work by understanding the importance of bank erosion as a cause of water quality problems in streams and targeting of management practices to reduce bank erosion.

Technical Abstract: Sediment and nutrients continue to degrade surface waters even as the targeting and efficacy of erosion management practices have improved. This study investigated the influence of land use, stream order, and season on streambank erosion and phosphorus (P) transport in the Central Claypan Region of northeast Missouri. The erosion pin method was used to measure bank erosion at 37 sites in Crooked and Otter Creek watersheds from 2008 to 2011; sites were stratified by stream order and land use, with seasonal measurements made 3 times per year. At 18 of the sites, bank vegetation data were collected and upstream watershed characteristics acquired. Eroding banks accounted for an average of 53% of the total bank length across all sites. Mean sediment bank recession rate was 7.1 cm/y and mean linear erosion rate was 99 kg/ m/y. Season was the only significant factor, with much greater soil loss occurring during the winter months. Land use and stream order were not significant factors. Watershed scale estimates showed that streambanks contributed an average of 83% of the annual in-stream sediment and 57% of the total P loss, clearly demonstrating the impact that bank erosion has on stream water quality in this region. Regression analyses using riparian vegetation and watershed variables resulted in a best fit model that accounted for only 48% of the variability in streambank erosion. Thus, existing land uses, bank vegetation, stream order, and watershed characteristics were not the primary controls on streambank erosion rates. Other factors, such as historic land use changes, stream channelization, and the damming of the Salt River have resulted in major alterations to stream hydrology and geomorphology in these watersheds that have not yet re-equilibrated. These over-arching factors, in combination with season, continue to be the main factors controlling streambank erosion in these watersheds.