Modelling of atrazine loss in surface runoff from agricultural watershed

There have been growing concerns over the negative effect of pesticide usage on human health and environmental sustainability. It has been found out that atrazine, a widely used herbicide, threatens ecosystems. Its residues after application can be discharged into water bodies, and thus contaminate surface water and pose risks to public health. An integrated modelling system was developed to estimate atrazine losses through surface runoff. This model includes a distributed hydrological model, a pesticide adsorption model, relational databases, and a geographic information system. The proposed model can simulate atrazine losses due to runoff through the consideration of emission, degradation, adsorption, and movement of atrazine in dissolved and adsorbed phases at the top soil layer. A case study was carried out in the Auglaize-Blanchard Watershed. A comparison between observed and predicted data during May 1997 to April 1998 was conducted. The correlation coefficients are over 0.9 and the statistical significance level was approximately 5%, indicating a reasonable prediction accuracy. The modelling results provide useful decision support for water quality management.