A review of pesticide fate and transport simulation at watershed level using SWAT: Current status and research concerns

Authors: WANG, RUOYU - University Of California; YUAN, YONGPING - Environmental Protection Agency (EPA); YEN, HAW - Texas Agrilife Research; GRIENEISEN, MICHAEL - University Of California; Arnold, Jeffrey; WANG, DAN - California Environmental Protection Agency; WANG, CHAOZI - China Agricultural University; ZHANG, MINGHUA - University Of California

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2019
Publication Date: 3/12/2019
Citation: Wang, R., Yuan, Y., Yen, H., Grieneisen, M., Arnold, J.G., Wang, D., Wang, C., Zhang, M. 2019. A review of pesticide fate and transport simulation at watershed level using SWAT: Current status and research concerns. Science of the Total Environment. 669:512-526. https://doi.org/10.1016/j.scitotenv.2019.03.141.
DOI: https://doi.org/10.1016/j.scitotenv.2019.03.141

Interpretive Summary: The use of pesticides in agriculture can alleviate pest stress and increase crop production. However, pesticides can runoff from agricultural fields into rivers and lakes used for drinking water and recreation, causing health concerns. The Soil and Water Assessment Tool (SWAT) has been used to model the fate and transport of pesticides and determine land management alternatives to reduce exposure. In this study, we performed a rigorous review of published studies that used SWAT for pesticide modeling (over 50 studies). This review provides recommendations for improving pesticide fate and transport algorithms in SWAT. Future improvements are also recommended that will address concerns of local stakeholders during model implementation.

Technical Abstract: The application of pesticides in agriculture is a widely-used way to alleviate pest stresses. However, it also introduces various environmental concerns due to the offsite movement of pesticide residues towards receiving water bodies. While the application of process-based modeling approaches can provide quantitative information on pesticide exposure, there are nonetheless growing requirements for model development and improvement to better represent various hydrological and physico-chemical conditions at watershed scale, and for better model integration to address environmental, ecological and economic concerns. The Soil and Water Assessment Tool (SWAT) is an ecohydrological model used in over 3000 published studies, including about 50 for simulating pesticide fate and transport at the watershed scale. To better understand its strengths and limitations, we conducted a rigorous review of published studies that have used SWAT for pesticide modeling. This review provides recommendations for improving the interior algorithms (fate simulation, pathway representation, transport/pollution control, and other hydrological related improvement) to better represent natural conditions, and for further extension of pesticide exposure modeling using SWAT by linking it with other models or management tools to effectively address the various concerns of environmental researchers and local decision makers. Going beyond past studies, we also recommend future improvement to fill research gaps in developing modularized field level simulation, improved BMPs, new in-pond and in-stream modules, and the incorporation of soft data. Our review pointed out a new insight of pesticide fate and transport modeling at watershed level, which should be seen as steps leading to the direction for model development, as well as better addressing management concerns of local stakeholders for model implementation.