Abstract
Excess nutrients and herbicides remain two major causes of waterbody impairment globally. In an attempt to better understand pollutant sources in the Big Sandy Creek Watershed (BSCW) and the prospects for successful remediation, a program was initiated to assist agricultural producers with the implementation of best management practices (BMPs). The objectives were to (1) simulate BMPs within hotspots to determine reductions in pollutant loads and (2) to determine if water-quality standards are met at the watershed outlet. Regression-based load estimator (LOADEST) was used for determining sediment, nutrient and atrazine loads, while artificial neural networks (ANN) were used for determining E. coli concentrations. With respect to reducing sediment, total nitrogen and total phosphorus loads at hotspots with individual BMPs, implementing grassed waterways resulted in average reductions of 97%, 53% and 65% respectively if implemented all over the hotspots. Although reducing atrazine application rate by 50% in all hotspots was the most effective BMP for reducing atrazine concentrations (21%) at the gauging station 06883940, this reduction was still six times higher than the target concentration. Similarly, with grassed waterways established in all hotspots, the 64% reduction in E. coli concentration was not enough to meet the target at the gauging station. With scaled-down acreage based on the proposed implementation plan, filter strip led to more pollutant reductions at the targeted hotspots. Overall, a combination of filter strip, grassed waterway and atrazine rate reduction will most likely yield measureable improvement both in the hotspots (>20% reduction in sediment, total nitrogen and total phosphorus pollution) and at the gauging station. Despite the model’s uncertainties, the results showed a possibility of using Soil and Water Assessment Tool (SWAT) to assess the effectiveness of various BMPs in agricultural watersheds.
Document Type
Article
Publication Date
2021
Digital Object Identifier (DOI)
https://doi.org/10.3390/su13010103
Funding Information
This research was funded by the U.S. Department of Agriculture—National Institute of Food and Agriculture (Hatch project NEB-21-177). The authors also thank the Nebraska Department of Environment and Energy (NDEE) for the support.
Related Content
The following are available online at https://www.mdpi.com/2071-105 0/13/1/103/s1, Figure S1: Error histogram with 20 bins and best validation performance, Figure S2: Observed and ANN-simulated E. coli concentrations at the gauging station, Figure S3: Land use map of BSCW, Figure S4: Slope map of BSCW, Figure S5: Box plots showing the distributions of annual reductions (n = 13) using no-till, Figure S6: Box plots showing the distributions of annual reductions (n = 13) using crop rotation, Figure S7: Box plots showing the distributions of annual reductions (n = 13) using filter strips, Figure S8: Box plots showing the distributions of annual reductions (n = 13) using grassed waterway, Figure S9: Box plots showing the distributions of annual reductions (n = 13) using terrace, Figure S10: Box plots showing the distributions of annual reductions (n = 13) using reduced atrazine rate, Figure S11: Average monthly (growing season) reduction in loadings using no-till at the target subwatersheds, Figure S12: Average monthly (growing season) reduction in loadings using crop rotation at the target subwatersheds, Figure S13: Average monthly (growing season) reduction in loadings using filter strips at the target subwatersheds, Figure S14: Average monthly (growing season) reduction in loadings using grassed waterway at the target subwatersheds, Figure S15: Average monthly (growing season) reduction in loadings using terrace at the target subwatersheds, Figure S16: Average monthly (growing season) reduction in loadings using reduced atrazine rate at the target subwatersheds, Table S1: Management operation for land in corn/soybeans rotation and pasture management, Table S2: SWAT parameters and their final values used in calibration for the Big Sandy Creek Watershed, Nebraska SWAT model.
The supplementary file is also available for download as the additional file listed at the end of this record.
Repository Citation
Abimbola, Olufemi; Mittelstet, Aaron; Messer, Tiffany L.; Berry, Elaine; and van Griensven, Ann, "Modeling and Prioritizing Interventions Using Pollution Hotspots for Reducing Nutrients, Atrazine and E. coli Concentrations in a Watershed" (2021). Biosystems and Agricultural Engineering Faculty Publications. 238.
https://uknowledge.uky.edu/bae_facpub/238
Supplementary file
Notes/Citation Information
Published in Sustainability, v. 13, issue 1, 103.
Copyright: © 2020 by the authors. LicenseeMDPI, Basel, Switzerland.
This article is an open access article distributed under the terms and conditions of the CreativeCommonsAttribution (CCBY) license (https://creativecommons.org/licenses/by/4.0/).