Stream channel storage: Closing the watershed total phosphorus budget

William J Beck; John L Kovar; Thomas M Isenhart; Peter L Moore; Suroso Rahutomo; Keith E Schilling; Richard C Schultz; Michael L Thompson; Calvin F Wolter; Matthew T Streeter; Kevin J Cole; Mark D Tomer

doi:10.1002/jeq2.70159

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Stream channel storage: Closing the watershed total phosphorus budget

Journal article

Open access

Peer reviewed

Stream channel storage: Closing the watershed total phosphorus budget

William J Beck, John L Kovar, Thomas M Isenhart, Peter L Moore, Suroso Rahutomo, Keith E Schilling, Richard C Schultz, Michael L Thompson, Calvin F Wolter, Matthew T Streeter, …

Journal of environmental quality, Vol.55(2), e70159

03/2026

DOI: 10.1002/jeq2.70159

PMCID: PMC12993114

PMID: 41840853

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https://doi.org/10.1002/jeq2.70159View

Published (Version of record) Open Access

Abstract

A 3-year total phosphorus (TP) budget was created for Walnut Creek, a ∼5200 ha agricultural watershed in central Iowa. The budget, developed from measures of streambank erosion, overland flow, baseflow, and flux to floodplain storage, was created with the specific goal of estimating in-channel storage contributions to annual TP loads-a component often poorly understood and rarely quantified at the watershed scale. Remobilization of in-channel sediment-bound P storage was estimated to dominate contribution to annual P loads, with overland flow the second greatest contributor. Streambanks represented only a minor contribution to loads and were surpassed in importance by baseflow dissolved P in drought years with reduced direct runoff. Although flux to floodplain storage was negligible, due to relatively low peak flows over the study's duration, and the degree of channel incision, the floodplain would represent a substantial P storage opportunity during years with greater peak flows. High-discharge events delivered the majority of the annual P load in two of the three study years, and the impact of these events is predicted to increase with progression of channel evolution and climate-driven increases in precipitation event intensity. Restoration of watershed hydrology (e.g., reduction of peak flows) and increased P flux to long-term floodplain storage through enhancement of channel-floodplain connectivity will have the greatest impact for decreasing annual P loads.

Environmental Monitoring

Iowa

Phosphorus - analysis

Rivers - chemistry

Water Movements

Water Pollutants, Chemical - analysis

Details

Title: Subtitle: Stream channel storage: Closing the watershed total phosphorus budget
Creators: William J Beck - Iowa State University
John L Kovar - National Laboratory for Agriculture and the Environment
Thomas M Isenhart - Iowa State University
Peter L Moore - Iowa State University
Suroso Rahutomo - Palm Research Center
Keith E Schilling - University of Iowa
Richard C Schultz - Iowa State University
Michael L Thompson - Iowa State University
Calvin F Wolter - University of Iowa
Matthew T Streeter - University of Iowa
Kevin J Cole - National Laboratory for Agriculture and the Environment
Mark D Tomer - National Laboratory for Agriculture and the Environment
Resource Type: Journal article
Publication Details: Journal of environmental quality, Vol.55(2), e70159
DOI: 10.1002/jeq2.70159
PMID: 41840853
PMCID: PMC12993114
NLM abbreviation: J Environ Qual
ISSN: 0047-2425
eISSN: 1537-2537
Publisher: Wiley
Grant note: 2013-67019-21393 / Agriculture and Food Research Initiative
Language: English
Date published: 03/2026
Academic Unit: IIHR--Hydroscience and Engineering; School of Earth, Environment, and Sustainability
Record Identifier: 9985147088602771

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