Modeling fate and transport of pesticides from dryland agriculture using SWAT model

• Published in: Journal of environmental management 2023-05, Vol.334, p.117457-117457, Article 117457
• Main Authors: Dogan, F. Nihan, Karpuzcu, M. Ekrem
• Format: Article
• Language: English
• Subjects: adsorption; Agriculture; arid lands; basins; Chlorpyrifos; Drinking Water; Drinking water basin; environmental management; Environmental Monitoring - methods; Fenpropimorph; landscapes; Models, Theoretical; Pesticides; Pesticides - analysis; Rivers; sediments; soil; Soil and Water Assessment Tool model; SWAT; Water Pollutants, Chemical - analysis; watersheds
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2023.117457

The aim of this study was to understand pesticide fate and transport from dryland agriculture in a major drinking water basin using SWAT and to identify critical source areas in the basin. Hydrological calibration results indicated satisfactory simulation of hydrologic processes within the catchment. Long term average observed sediment values (0.16 ton/ha) were compared with the annual average simulated SWAT outputs (0.22 ton/ha). Generally, the simulated concentrations were higher than the observed values, but the distribution pattern and trends were similar among the months. Average concentrations in water were 0.036 μg/L and 0.006 μg/L for fenpropimorph and chlorpyrifos, respectively. Transfer rates of pesticides from landscape to rivers showed that 0.36% of fenpropimorph and 0.19% of the applied amount of chlorpyrifos were exported to the river. Higher amount of fenpropimorph transport from land to the reach was attributed to its lower Koc (soil adsorption coefficient) value compared to chlorpyrifos. Higher amounts from HRUs were observed in the application month (April) and following month (May) for fenpropimorph, while the months after September showed higher amounts for chlorpyrifos. The specific HRUs (Hydrological Response Units) located in sub-basins 3, 5, 9 and 11 presented highest dissolved pesticide amounts, while HRUs in sub-basins 4 and 11 exhibited highest concentrations for adsorbed pesticides. Best management practices (BMPs) were recommended in critical subbasins to protect the watershed. Despite the limitations, the results demonstrate the potential contributions of modeling in terms of assessing pesticide loadings, critical zones and application timing. •SWAT model can reasonably capture pesticide pollution trends in the basin.•Rainfall events following pesticide application result in peak concentrations.•Pesticide fate and transport strongly depends on Koc and degradation rate constant.•BMPs are recommended for critical areas prone to pesticide pollution in the basin.