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Assessment of the Environmental Fate of the Herbicides Flufenacet and Metazachlor with the SWAT Model
Author(s) -
Fohrer Nicola,
Dietrich Antje,
Kolychalow Olga,
Ulrich Uta
Publication year - 2014
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0382
Subject(s) - environmental science , swat model , soil and water assessment tool , water resource management , ecology , geography , biology , surface runoff , cartography , streamflow , drainage basin
This study aims to assess the environmental fate of the commonly used herbicides flufenacet and metazachlor in the Northern German Lowlands with the ecohydrological Soil and Water Assessment Tool (SWAT model) and to test the sensitivity of pesticide‐related input parameters on the modeled transport dynamics. The river discharge of the Kielstau watershed was calibrated (Nash‐Sutcliffe efficiency [NSE], 0.83; r 2 = 0.84) and validated (NSE, 0.76; r 2 = 0.77) for a daily time step. The environmental fate of metazachlor (NSE, 0.68; r 2 = 0.62) and flufenacet (NSE, 0.13; r 2 = 0.51) was simulated adequately. In comparison to metazachlor, the simulated flufenacet concentration and loads show a lower model efficiency due to the weaker simulation of the stream flow. The in‐stream herbicide loads were less than 0.01% of the applied amount in the observed time period and thus not in conflict with European Environmental Legislation. The sensitivity analysis showed that, besides the accurate simulation of stream flow, the parameterization of the temporal and spatial distribution of the herbicide application throughout the watershed is the key factor for appropriate modeling results, whereas the physicochemical properties of the pesticides play a minor role in the modeling process.