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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING WATER QUALITY IN AGRICULTURAL WATERSHEDS UNDERLAIN BY CLAYPAN AND RESTRICTIVE LAYER SOILS

Location: Cropping Systems and Water Quality Research

Title: Process-based index modeling of landscape vulnerability to off-site agrichemical movement

Authors
item Shea, Pat -
item Milner, Maribeth -
item Hosseini, Atefeh -
item Dhakal, Kundan -
item Bernards, Mark -
item Baffaut, Claire
item Lerch, Robert

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 23, 2013
Publication Date: N/A

Technical Abstract: dentifying areas vulnerable to off-site agrichemical movement and surface and ground water contamination through conventional data collection is labor-intensive, costly and time-consuming. To promote efficient agrichemical use and protect water resources, a process-based index model was developed to assess landscape vulnerability to runoff and leaching. The model is based on hydrologic/landscape characteristics [including saturated hydraulic conductivity, soil organic matter, texture, clay content and mineralogy, pH, depth to a restrictive layer, whole fraction erodibility, drainage class, flooding frequency and slope] and the physicochemical properties of the agrichemical of interest [including adsorption (organic carbon partition coefficient), relative persistence (half-life), and susceptibility to abiotic hydrolysis]. The watershed-scale (regional) model incorporates chemical dissipation and hydrologic functions and utilizes the 1:24,000-scale USDA-NRCS Soil Survey Geographic Database (SSURGO), although laser imaging detection and ranging (LiDAR) data can be used for more detailed assessments. Because mitigating contamination of surface and ground waters requires implementation of conservation management practices, the model was adapted to field scale using data from a Missouri research site. Available data included saturated hydraulic conductivity, pH, organic matter, 5 x 5 m resolution elevation from which slope was derived, and Agricultural Policy/Environmental eXtender (APEX)-modeled daily moisture content. Mathematical functions were imported into ArcGIS and maps generated showing relative potential for off-site movement across the field. These qualitative regional and field-scale models can help identify vulnerable areas within watersheds and agricultural fields to target and prioritize sites for implementation of best management practices and regulatory strategies that effectively address water quality concerns.

Last Modified: 10/20/2014
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