Phosphorus Contributions from Eroding Streambanks

Streambank erosion on Onion Creek in Story County, Iowa

Title:  Phosphorus contributions from eroding streambanks

Location:  Onion Creek, Story and Boone Counties, IA; Nishnabotna River watershed, SW Iowa

Time Period:  2016-2019

Research Team:  Peter Moore, Forrest Williams, Tom Isenhart, John Kovar, John Thomas (Hungry Canyons Alliance), Colton Dodson.

Project Description:  Stream bed and bank erosion represents a significant contribution to phosphorus (P) export from Iowa’s streams, worsening downstream eutrophication and water quality concerns.  The size of this contribution is not well known in time or space, and may depend on many factors including watershed size, geomorphology, land use, stream channelization history and hydrological regime, and soil composition and texture. This project investigated the distribution of streambank erosion in time and space in two contrasting watersheds in Iowa. Erosion and P export was monitored in the field monthly over a two-year period in the Onion Creek watershed, a 20 square-mile catchment on the Des Moines Lobe near Ames. Remote sensing and GIS methods were developed to study the same processes within the much larger Nishnabotna River watershed (2806 square miles) in the deep-loess region of southwest Iowa.

Publications:  Williams, F., 2019, AIMM: A method for measuring bank erosion on a statewide scale, Graduate Theses and Dissertations. 17360.

Funders:  Iowa Nutrient Research Center, Hungry Canyons Alliance