Phosphorus Inputs from Streambanks
Title: Watershed-scale phosphorus inputs from streambanks
Location: Onion Creek, Story and Boone Counties, IA; Nishnabotna River watershed, SW Iowa, Oakland; statewide
Time Period: 2019-2021
Research Team: Peter Moore, Tom Isenhart, Keith Schilling, John Kovar, John Thomas (Hungry Canyons Alliance)
Project Description: Streambanks were identified in the Iowa Nutrient Reduction Strategy as a potentially important but poorly quantified source of phosphorus (P) to surface waters. A 2016 review of literature cited bank contributions ranging from 6% to 93% of watershed P export in studies around the world. The wide range of results reflects substantial variation in time within watersheds, as well as spatial variation across watersheds in differing landscapes. This study addresses both temporal and spatial variability in P contributions from streambanks in Iowa. We are continuing an ongoing long-term study of the seasonal and inter-annual variability of bank erosion throughout the small (20 square mile) Onion Creek watershed in central Iowa. We are also using a remote sensing-based methodology called AIMM to automatically detect bank erosion across the state, allowing examination of spatial variation in P contributions. A third objective of this research is to use these methods to evaluate the effectiveness of bank stabilization and flow-training structures in reducing streambank contributions of P along adjacent stabilized and un-stabilized segments of the West Nishnabotna River, southwest Iowa.
Funders: Iowa Nutrient Research Center, Hungry Canyons Alliance
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