Pesticide modelling for a small catchment using SWAT-2000

Area of Science:

• Environmental Science
• Hydrology
• Agricultural Science

Background:

• Pesticide contamination of water bodies is a significant environmental concern.
• Understanding pesticide transport in agricultural catchments is crucial for effective water resource management.
• Tile drainage is a common feature in agricultural landscapes, influencing water and chemical movement.

Purpose of the Study:

• To assess the predictive capability of the Soil and Water Assessment Tool (SWAT) for pesticide concentrations in streamflow.
• To evaluate the impact of different pesticides and cropping patterns on pesticide losses.
• To explore management options for mitigating pesticide loads in agricultural catchments.

Main Methods:

• Monitoring of pesticide concentrations in stream flow from the Colworth catchment (142 ha) over 14 months.
• Utilizing hydrological modeling with crop growth and evapotranspiration simulation within SWAT 2000.
• Modeling specific pesticides: terbuthylazine, terbutryn, cyanazine, and bentazone.

Main Results:

• Close agreement was observed between SWAT-predicted and observed pesticide concentrations at the catchment outlet.
• The Soil and Water Assessment Tool (SWAT) demonstrated sound performance in hydrological and pesticide modeling.
• Scenario trials indicated potential for management interventions to reduce pesticide loads.

Conclusions:

• SWAT is a reliable tool for understanding pesticide behavior and predicting concentrations at the catchment scale.
• The study provides a validated modeling approach for assessing agricultural impacts on water quality.
• Findings support the use of SWAT for developing strategies to minimize pesticide contamination in surface waters.