Estimation of Agricultural Pesticide Use in Drainage Basins Using Land Cover Maps and County Pesticide Data
By Naomi Nakagaki and David M. Wolock
U.S. GEOLOGICAL SURVEY
Open-File Report 2005-1188
Sacramento, California 2005
ONLINE ONLY
National Water-Quality Assessment Program
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Abstract
A geographic information system (GIS) was used to estimate
agricultural pesticide use in the drainage basins of streams that are studied
as part of the U.S. Geological Survey’s National Water-Quality Assessment
(NAWQA) Program. Drainage basin pesticide use estimates were computed by intersecting
digital maps of drainage basin boundaries with an enhanced version of the National
Land Cover Data 1992 combined with estimates of 1992 agricultural pesticide use
in each United States county. This report presents the methods used to quantify
agricultural pesticide use in drainage basins using a GIS and includes the estimates
of atrazine use applied to row crops, small-grain crops, and fallow lands in 150
watersheds in the conterminous United States. Basin atrazine use estimates are
presented to compare and analyze the results that were derived from 30-meter and
1-kilometer resolution land cover and county pesticide use data, and drainage
basin boundaries at various grid cell resolutions. Comparisons of the basin atrazine
use estimates derived from watershed boundaries, county pesticide use, and land
cover data sets at different resolutions, indicated that overall differences were
minor. The largest potential for differences in basin pesticide use estimates
between those derived from the 30-meter and 1-kilometer resolution enhanced National
Land Cover Data 1992 exists wherever there are abrupt agricultural land cover
changes along the basin divide. Despite the limitations of the drainage basin
pesticide use data described in this report, the basin estimates provide consistent
and comparable indicators of agricultural pesticide application in surface-water
drainage basins studied in the NAWQA Program.
CONTENTS
Abstract
Introduction
Background
Purpose and Scope
Acknowledgments
GIS Datasets
Drainage Basin Boundaries
Land Cover
30-Meter Resolution
1-Kilometer Resolution
County Agricultural Pesticide Use
Estimating Agricultural Pesticide Use in Drainage Basins
Basin Pesticide Use Estimated from the 1-Kilometer Resolution
Land Cover Dataset
Steps to Generate a 1-Kilometer Resolution Pesticide Use Grid
Steps to Estimate the Basin Pesticide Use Using a 1-Kilometer
Resolution Pesticide Use Grid
Basin Pesticide Use Estimated from the 30-Meter Resolution
Land Cover Dataset
Results
Which Resolution is the Most Appropriate for Estimating Agricultural
Pesticide Use in Drainage Basins?
Limitations of the Agricultural Pesticide Use Estimates in
Drainage Basins
Other Applications of the Methods
Future Directions
Summary
Endnotes
References Cited
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Water Resources of California
