Modeling and Risk Analysis of Nonpoint-Source Pollution Caused by Atrazine Using Swat

Abstract

ABSTRACT. The SWAT (Soil Water Assessment Tool) griculture is the main cause of nonpoint-source (NPS) pollution that affects streams and aquifers throughout the country (Yu et al., 2004). The driving force of NPS pollution is the rainfall-runoff process, which tends to be a complex non-linear, time-varying, and spatially distributed process in agricultural watersheds. This and other related processes may be quantified by means of physical hydrologic models. Likewise, hydrologic modeling is often the first step in the development of a spatial decision support system suitable for identifying areas that are vulnerable to nutrient and pesticide contamination (Lim et al., 2001), evaluating the effect of management practices, and performing risk analyses for different scenarios.In agricultural watersheds, variable amounts of pesticides can be released to streams and aquifers through surface runoff and leaching, jeopardizing sources of drinking water. On the other hand, pesticides make high agricultural yields possible. Atrazine is a key input in corn production throughout the world. However, it is easily carried to streams by rainfall runoff because of its high solubility. Modeling is a valuable

Dominant controls on pesticide transport from tile to catchment scale: Lessons from a minimalist model

“…It is assumed that the sorption process is linear and reversible and that the equilibrium is reached instantaneously. This assumption is consistent with our parsimonious approach, and can be found in similar, recent works on pesticide transport (e.g., Vasquez‐Amabile et al [2006] relative to the SWAT model, and Chinkuyu et al [2005], relative to GLEAMS and RZWQM). Other studies [e.g., Larsbo et al , 2005] refer to the Freundlich isotherm.…”

“…The timing of pesticide application relative to major hydrologic events, is known to play a key role in determining pesticide releases [e.g., Chiovarou and Siewicki , 2007; Luo and Zhang , 2009]. Given their strong correlation to corn planting dates [ Vasquez‐Amabile et al , 2006; Larose et al , 2007], at the river station we used the progressive acreage planted curves—which are available from the USDA National Agricultural Statistical Service for the eastern Illinois region (∼6000 km 2 )—as an estimator and assumed that atrazine was applied only on the area of land that was progressively planted with corn. The USDA database also reports on the averaged atrazine application rates for eastern Illinois for all of the years considered in the study; we refer to those values for our analysis at station R5, as this was the most accurate information we could collect.…”

Tillage Practices Usage in Early Warning Prediction of Atrazine Pollution

“…The statistics for the prediction of atrazine concentration were within ranges reported by other researchers, such as Neitsch et al (2002b) and Vazquez-Amabile et al (2006). Neitsch et al (2002b) Larose et al (2007) for this location.…”

“…In SWAT modeling research by Vazquez-Amabile et al (2006) to simulate atrazine concentrations in the St. Joseph watershed in northeastern Indiana, atrazine application was made as a function of percentage crop planted using USDA National Agricultural Statistics Service (NASS) crop progress reports. A multiple application ratio was then generically applied to all hydrologic response units (HRUs).…”

Impact of Watershed Subdivision and Soil Data Resolution on SWAT Model Calibration and Parameter Uncertainty1

“…The St. Joseph River is a major source of drinking water supply for the 250,000 citizens of Fort Wayne. High levels of herbicide atrazine above Environmental Protection Agency’s action limit of three parts per billion was reported in SJRW between 1995 and 1998 (Vazquez‐Amabile et al. , 2006).…”