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An integrated RICEWQ-AnnAGNPS modeling system to evaluate the fate and transport of thiobencarb in Colusa Basin, Northern California
Citation:
Wang, R., R. Bingner, Y. Luo, Y. Yuan, M. Locke, D. Denton, AND M. Zhang. An integrated RICEWQ-AnnAGNPS modeling system to evaluate the fate and transport of thiobencarb in Colusa Basin, Northern California. 2018 SETAC North America Annual Meeting, Sacramento, CA, November 04 - 08, 2018.
Impact/Purpose:
Presented at the 2018 SETAC North America Annual Meeting
Description:
As a pre-emergent or early post-emergent herbicide, thiobencarb is widely used to control for grasses and broadleaf weeds in rice fields in Northern California. Released paddy water containing thiobencarb may pose ecological risks to non-targeted organisms (e.g., aquatic invertebrates) living in downstream water bodies. Current watershed level models usually lack proper mechanisms to accurately represent the complicated hydrological and water quality conditions in rice fields. Therefore, they are not suitable to re-capture the fate and transport of herbicides like thiobencarb in this setting. In this research, we develop an integrated modeling system: RICEWQ-Annualized Agricultural Nonpoint Source Pollution (AnnAGNPS) to correctly determine the dynamics of thiobencarb in rice fields, as well as the subsequent processes after paddy water is discharged and transported downstream. The RICEWQ model, which is specifically designed for rice fields, was first setup at all rice paddies in the Colusa Basin in Northern California to simulate paddy water discharge and thiobencarb exposure to nontargeted organisms at the edge of fields. The AnnAGNPS, a watershed level model, was setup in the same region to capture the flow discharge of this herbicide from land uses other than rice. Landscape processes of thiobencarb from fields to reaches and channel routings are also simulated by the AnnAGNPS model. Consequently, the impact of an upstream rice herbicide application on exposures at receiving water bodies can be evaluated, with the implementation of the proposed coupled modeling system in Colusa Basin.
