S-EPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Athens, GA 30605-2720
Research and Development
EPA/600/S-93/010 February 1994
ENVIRONMENTAL
RESEARCH BRIEF
PATRIOT-A Methodology and Decision Support System for Evaluating the
Leaching Potential of Pesticides
J. C. Imhoff*. P. R. Hummer*, J. L Kittle, Jr.**, and R. F. Carsel***
Abstract
The Pesticide Assessment Tool for Rating Investigations
of Transport (PATRIOT) is a methodology for providing rapid
analyses of groundwater vulnerability to pesticides on a re-
gional, state, or local level. An appropriate measure of ground-
water vulnerability is achieved by quantifying the leaching
potential of a pesticide in terms of the mass transported to the
top of the water table. The PATRIOT software package inte-
grates, in a personal computer environment, a tool that enables
scientifically sound analysis of pesticide leaching potential with
the data needed to use the tool for area-specific analyses
anywhere in the conterminous United States. PATRIOT is
comprised of (i) a chemical fate and transport model (PRZM-2),
(ii) a comprehensive database, (iii) an interface that allows the
user to explore the database and select the data appropriate to
characterize local environmental factors and pesticide applica-
tion scenarios, (iv) a directed sequence of interaction that
guides the user in providing all the necessary information to
perform alternative model analyses, and (v) effective, user-
selected methods of summarizing and visualizing model re-
sults.
*AQUA TERRA Consultants, Ouray, CO 81427.
"AQUA TERRA Consultants, Decatur, GA 30030.
'"Environmental Research Laboratory, USEPA, Athens, GA 30605.
Introduction
One of the most pressing concerns in agrichemical man-
agement today, particularly in agricultural areas, is protecting
our nation's groundwater supplies from invasion by pesticides.
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
provides state governments with a strong mandate to develop
pesticide management plans. In order to make sound deci-
sions, environmental managers at the federal, state, and local
levels need to understand the potential for pesticides to leach
from application sites through the underlying soil's unsaturated
zone and into the groundwater. Pesticide leaching is highly site-
specific, and predicting the expected extent of leaching is not a
simple task. The tendency to leach to groundwater is deter-
mined by the combined factors of climate, pesticide
chemodynamics, soil properties, agricultural practices, and
depth to groundwater. Accurate estimation of leaching potential
requires analysis techniques that consider all of these factors.
The EPA Office of Science, Planning and Regulatory
Evaluation has initiated a research program to develop infor-
mation systems for use in preventing or minimizing groundwa-
ter contamination by pesticides. The purpose of this program is
to provide practical tools, with a strong scientific base, to state
agencies in order to support the development of local pesticide
management plans as mandated by FIFRA and implemented
by the EPA Office of Pesticide Programs.
Printed on Recycled Paper
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PATRIOT integrates existing technologies and
hydrogeologic information into a framework for risk assessment
and management of agricultural pesticides. The system enables
state and local decision makers to rapidly analyze information
about pesticides, soils, and other relevant factors in order to
make sound recommendations about pesticide use that will
protect groundwater quality. Data investigations and model
analyses can be evaluated within state, county, U.S. Depart-
ment of Agriculture Major Land Resource Area, or U.S. Geologi-
cal Survey Hydrologic Cataloging Unit boundaries.
The primary users of PATRIOT are expected to be state
personnel charged with developing local pesticide management
plans. An additional user community will reside within EPA
Headquarters and Regional Offices, where the tool will aid those
involved in evaluating specific pesticides or pesticide manage-
ment plans. Although data analysis is not the primary function of
the software package, it is likely that a broad base of environ-
mental professionals may adopt PATRIOT as a convenient tool
to explore the environmental data that support model analyses.
Figure 1 summarizes the PATRIOT groundwater vulner-
ability assessment software package. The input, process, and
output features of PATRIOT illustrated in the figure are de-
scribed below.
Input. Evaluation of groundwater vulnerability within an
area of interest requires data on (i) the influx of water and
chemical, (ii) soils properties and distribution, (iii) pesticide
chemodynamics, (iv) agricultural practices, and (v) the distance
from the soil surface to groundwater.
Stated simply, the concept of PATRIOT is to integrate data
for rainfall, soils, pesticides, and cropping practices to rapidly
estimate area-specific pesticide leaching potential. These analy-
ses serve as a means of assessing groundwater vulnerability
and developing pesticide management strategies. To accom-
plish these ends, model analyses require data of national scope,
but at a scale that allows determination of leaching potential at
state and local levels.
Processes. PATRIOT enables its users to investigate avail-
able data, select data needed to perform pesticide leaching
analyses for scenarios or areas of interest, and assess ground-
water vulnerability based on the results of a mathematical
model. Data investigation capabilities include extensive search-
ing, ranking, statistical, and display functions that enable users
to explore and understand the PATRIOT database prior to, or
independent of, model analyses. A directed mode of database
interaction dedicated to developing the input to drive one-
dimensional unsaturated zone model analysis of flow and chemi-
cal transport is included. PATRIOT produces an appropriate
estimation of leaching of pesticides to the water table by using
scientifically sound methods and area-specific data.
Output. The end point of PATRIOT analyses is the top of the
water table. The primary outputs are graphic comparisons of
model results of leaching potential for various combinations of
pesticide, soil, agricultural practice, and rainfall. Output options
allow reporting of either unit- or area-weighted leaching analy-
ses aggregated within various geographic boundaries. For a
selected period of analysis, either average annual or total
leaching can be reported. In addition, PATRIOT enables the
viewing of many intermediate tables, maps, and graphics that
support the user and help him or her to understand the impact
of decisions in site characterization. A supplemental feature of
PATRIOT is the ability to model and report the results of Monte
Carlo simulation in order to evaluate the effects of uncertainty in
chemical and soil/hydraulic properties (e.g., decay rate, field
capacity) on pesticide mass leached to the water table.
Databases
Although many data types are potentially useful for support-
ing analysis of groundwater vulnerability to pesticides, the data
that are required to fuel the PRZM-2 model of chemical fate and
transport and allow assessment of pesticide leaching potential
with the desired level of detail include:
(a) Long-term daily rainfall records that can be used directly, or
with appropriate corrections for evaporation and irrigation,
to represent potential infiltration to the unsaturated zone at
locations across the conterminous United States.
(b) A comprehensive set of soils properties (e.g., percent sand,
percent clay, bulk density, percent organic carbon) that
determine pesticide migration through the unsaturated
zone.
(c) Data defining the geographic occurrence of soils within
appropriate geographic boundaries to support the develop-
ment of state and local pesticide management plans.
(d) Chemodynamic properties (i.e., half-life, organic carbon
partition coefficient) that determine persistence and trans-
port of commonly used agricultural pesticides.
(e) Region-specific cropping practices (i.e., dates for planting,
emergence, maturity, and harvest) for agricultural crops
commonly grown in the conterminous United States.
(f) Knowledge of, or data that specify, the crops to which
specific pesticides may be applied and the likely application
dates and rates.
(g) Information about the depth to groundwater for areas that
will be evaluated.
The PATRIOT software package provides comprehensive
databases that satisfy the needs for information on rainfall, soils
properties and occurrence, pesticide properties, and cropping
practices. Pesticide-crop relationships and depth-to-water table
estimates must be provided by the PATRIOT user. The at-
tributes of the PATRIOT database are:
Rainfall. Ten years of daily rainfall values are included at
184 first-order (primary) National Oceanic and Atmospheric
Administration weather stations across the conterminous United
States.
Soils. From the NRI/SOILS5 linked database [1] selected
properties for 24,000 soils series are included. A single soils
series is associated with each of 229,000 sample sites in the
conterminous United States that are classified as having agri-
cultural land use; expansion factors in the National Resources
Inventory database determine the area represented by each
sample site. Data for up to four soil layers within each soil series
include U.S. Department of Agriculture texture class and mini-
mum and maximum values for percent sand, percent clay,
organic matter, bulk density, and available water. In addition, a
Soil Conservation Service hydrologic group designation for
each soil series is included in the database.
Cropping. The PATRIOT database includes an EPA crop-
ping practice database [2] compiled from USDA data on the
customary planting, emergence, maturation, and harvesting
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Input
Process
Output
Investigate
Available Data
Select Data to
Represent Scenarios
or Areas of Interest
for Pesticide
Leaching Analysis
Perform Model
Simulations to
Assess Groundwater
Vulnerability
Unit Leaching Potential
for Selected Soils
....
_
-I-H-1-"-
Area-Weighted Leaching
Potential for Selected
Soils
••
Un
L(
PI
Jii -in
if] Tir
m "W ma rm
certainty in Pesticide
Baching Potential
Figure 1. PATRIOT groundwater vulnerability assessment software package.
dates for 32 major agricultural crops. Cropping dates are keyed
to all geographic boundary schemes supported for PATRIOT
analyses.
Pesticides. Values from the SCS/ARS/CES Pesticide Prop-
erties Database [3] for soil sorption coefficient and soil half-life
for approximately 125 active ingredients commonly found in
agricultural pesticides are included in PATRIOT.
Other Databases. Digital line graph databases are inte-
grated into PATRIOT that allow mapping of the results of
database searches within various geographic boundaries (state,
county, MLRA, hydrologic unit). A coordinate database for the
locations of rainfall records is also included.
Unsaturated Zone Model
PATRIOT integrates the PRZM-2 [4] chemical fate and
transport model of the unsaturated zone with supporting data-
bases. The tasks of preparing input for model analyses and
interpreting the model's results are supported by analysis and
graphics capabilities that are peripheral to the core model and
customized to allow efficient analysis of the specific problem that
PATRIOT addresses (i.e., leaching potential to the water table).
The use of EPA's PRZM-2 model in PATRIOT enables
three general capabilities:
(1) The model evaluates flow and transport through the unsat-
urated zone using scientifically sound methods. Advection,
dispersion, adsorption, and decay are considered.
(2) The model uses formulations that are sensitive to, and can
be evaluated by using, readily available environmental and
chemical data (soils properties, rainfall, cropping practices,
pesticide properties).
(3) The model is capable of comparing mass loadings at the top
of the groundwater table for different environmental sce-
narios; typical run times range from 1 to 60 minutes.
Interaction Framework
PATRIOT is designed specifically for minimal user input
and rapid analysis in a PC environment. Interaction with both the
model and the databases has been implemented using the
interface development tool AIDE [5]. For PATRIOT, AIDE has
been used to implement four major categories of user interac-
tion: (i) on-line documentation and assistance, (ii) analysis of
databases, (iii) development of model input and execution of the
model, and (iv) selection of evaluation options for model output.
Comprehensive on-line documentation and assistance has
been provided through the use of two tools: AIDE and Expert
Help [6]. AIDE features such as Limits (displays allowable
values for user responses to data queries) and Status (displays
system status in a window) provide a first level of on-screen
assistance to PATRIOT users. Additional assistance is provided
through the documentation tool Expert Help. After viewing an
initial, context-sensitive help message, Expert Help allows the
user to branch out in different directions in the documentation to
pursue information on related topics.
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Interaction with the databases has been enabled by imple-
menting option menus related to attribute searching, ranking
and statistical analysis, and display of products that result from
selecting the menu options (i.e., summary displays, graphics,
and mapping). In addition to menu selections, two other modes
of providing information are used: general data entry fields and
"toggled" data fields that only allow selection of "on" or "off
conditions. AIDE has been used to develop a directed mode of
database interaction dedicated to developing all the necessary
input for a variety of user-selected PRZM-2 analysis options.
Finally, menus have been developed that enable the user to
select various alternatives for compiling and viewing model
results.
PATRIOT provides supportive graphics at every stage
(data analysis, model input development, model results evalu-
ation) of the process of analyzing leaching.
The general graphics capabilities of PATRIOT are:
(1) Generation and presentation of tables (Figure 2), maps
(Figure 3), and plots (Figure 4) that clarify the impact of
decisions in scenario development that are antecedent or
ancillary to the model analyses.
(2) Display of a "worksheet" that summarizes the current status
of model scenario specification.
(3) Graphical comparison of either unit- or area-weighted leach-
ing analyses (Figure 5) aggregated within various geo-
graphic boundaries, as appropriate for regional, state or
local investigations.
(4) Plots of "non-exceedance probability" (FigureG), expressed
as a fraction (on the x axis) versus pesticide leached to the
top of the water table (on the y axis) to support uncertainty
analysis.
The graphics products of PATRIOT, all of which can all be
printed on a printer or plotter, are designed to provide much of
the information needed for individual hard copy reports on the
leaching potential of specific pesticides within specific environ-
mental scenarios.
Discussion of Capabilities
The PATRIOT software is comprised of three branches of
code: ANALYSIS, INPUT, and ESTIMATE. A typical application
of PATRIOT will require user interaction with all four databases:
rainfall, soil properties, pesticide properties, and cropping prac-
tices. PATRIOT embodies a "stepping stone" approach to
assessing pesticide leaching potential. That is, the results of
database search activities performed in the ANALYSIS branch
are a prerequisite to specifying model input in the INPUT branch,
and the input specification activities in the INPUT branch are
prerequisites to performing any of the model analysis alterna-
tives that are executed and summarized in the ESTIMATE
branch.
Providing the input needed to perform model analysis
requires iterative visits, first to the ANALYSIS branch and then
to the INPUT branch, to interact with each of the four databases.
The ANALYSIS branch enables the user to investigate each
database and to identify the appropriate data to fuel model
analyses of area- and pesticide-specific scenarios. These data
are stored in a buffer and identified in a "worksheet' to which the
INPUT branch refers as a first step in the effort to establish the
values for each data type that will be used to execute the model.
Within the INPUT branch, two activities are performed. First, for
model input that is supplied directly by the databases, the user
is allowed to view, refine, and assign to the model the data
resident in the buffer after search activity is completed in the
ANALYSIS branch. Second, the user is prompted to provide
additional input, independent of the databases, that is used to
establish model analysis options. A user enters the ESTIMATE
branch only after all databases have been investigated and after
all information necessary to perform a user-specified model
analysis option has been established. If the user attempts to
invoke an analysis by selecting an option in the ESTIMATE
branch before all the necessary data have been provided, he or
she will be returned to the INPUT branch, where an indicator of
missing data/decisions is provided.
When dealing with each of the databases, the user per-
forms iterative searches in the ANALYSIS branch, fine-tuning
the search criteria until the contents of the buffer satisfy the
desired scope of the model analysis (i.e., the proper amount of
data with the appropriate characteristics or geographic loca-
tion).
When a user first enters the INPUT branch, he or she is
prompted to define general run information (e.g., number of
analysis scenarios, standard or Monte Carlo ru n). After the basic
run characteristics have been defined, the interface grooms its
prompts to obtain all the information/decisions from the user and
the databases that are required to execute the specified analy-
sis.
After all the databases have been explored in the ANALY-
SIS branch, and all information required for model execution has
been specified in the INPUT branch, the user proceeds to the
ESTIMATE branch to specify output products and invoke model
execution. In a time span of minutes, the model computes
leaching potential and produces output in the user-selected
format. The user may view the model results for up to 10
combinations of pesticide/soil/cropping practices/infiltration, then
evaluate the results and define new runs, or, when results are
acceptable, save them in files or print hard copies.
Availability and System Requirements
PATRIOT model code is available from the Environmental
Research Laboratory, U.S. Environmental Protection Agency,
Athens GA 30605-2720. Requests, directed to the Laboratory's
Center for Exposure Assessment Modeling (CEAM), should
include four 3.5-inch diskettes, to which the code will be copied.
(Double-sided, high-density, DS/HD 1.44MB, error-free dis-
kettes, B=1 byte, K=1,024, M=1,048,576.) The user also can
obtain PATRIOT by dialing the CEAM bulletin board at 706-546-
3402 and downloading the model (approximately 1 to 1.5 hours
at 9600 baud).
No traditional hard copy users manual is available for
PATRIOT. Rather, the model comes with an on-line expert help
package that guides the user in analysis of data and in develop-
ment of input data for the PRZM-2 model and provides detailed
documentation on features and characteristics of PATRIOT.
The user invokes the on-line help feature by pressing the F1
function key on his or her PC.
PATRIOT was developed to run on a 386/486 IBM-compat-
ible personal computer. The PC must have 7 MB of combined
direct access and extended memory for optimal performance,
and approximately 20 MB of free disk space. A math coprocessor
is required; a VGA monitor that supports a minimum graphics
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Soil Series (Name)> Aura
Soil Number (Numeric Code)> 12864
Class
8
8
5
Percent
Sand
L H
30 70
50 85
60 95
Depth (cm)
SUR 20.3
SUB 149.9
SIR 182.9
Potential Crops
26 Peas 13 Cabbage 1 Corn 18 Tomatoes
Figure 2. Example PATRIOT summary table of properties for Aura soil series.
Percent
Clay
L H
7 20
15 35
3 32
Bulk Dens.
L H
1.17 1.60
1.50 1.70
1.45 1.64
Percent
Org. Mat.
L H
1.0 3.0
0.0 0.0
0.0 0.0
cm cnv3
Avail H20
L
0.11
0.07
0.01
H
0.17
0.15
0.12
HGRP
B
7 Soybeans
9 Wheat
Figure 3. Example PATRIOT map of counties in the New Jersey search area that contain soils satisfying search criteria.
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40
36
32
28
24
o
| 20
'g.
'8
£ 16
12
I
1972
1974 1976 1978
Monthly Precipitation Values for Met Station at NJ - Atlantic City
Figure 4. Example PATRIOT summary graphic of monthly rainfall from 1972 to 1980 recorded at the Atlantic City,
station.
Relative Area-Weighted Leaching Potential of Pesticide for Scenarios
1980
NJ, weather
6000
"o
,2 CT 4500
!i
8*
-^1 1500
8
5 o
a
t»
8
o
m
m
5 6
Scenario Number
10
CO
Scenario
1
2
3
4
5
6
7
8
9
10
Soil
Number
7961
7969
7973
7998
8030
12854
12864
12867
12868
12869
Soil Name
Mattapex
Matapeake
Sassafras
Chillum
Klej
Fort Mott
Aura
Hammonton
Hammonton
Downer
Unit Leach
(Kg/Ha)
0.021
0.132
0.386
0.050
0.827
0.252
0.303
0.385
0.195
0.399
Area (Ha)
486.
5751.
9315.
446.
3726.
2228.
17901.
3848.
4253.
4577.
Figure 5. Area-weighted leaching analyses for 10 PATRIOT modeling scenarios.
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Uncertainty Resulting from Variability in Decay Rate
1.00
0.75
0.50
0.25
0
0.09900 .12480 .15060 .17640 .20220 .22800 .25380 .27960 .30540
Mass of Pesticide Leached to Top of Water Table (Kg AI/Ha)
.33120 .3570
o
Q
d
Input Variable
Decay Rate
LYR
SUR
Mean
0.014
CV
7.194
Dist. Type
Normal
Figure 6. Plot of "non-exceedance probability" expressed as a fraction (x-axis) versus pesticide leached to the top of the water
table (y-axis) to support uncertainty analysis.
display of 640x480 pixels with 16 colors is strongly recom-
mended. Graphics for the PC emulate the ANSI Graphical
Kernel System (GKS) using OTG INTERACTED PATRIOT is
written in FORTRAN 77. If compilation of code is necessary, a
FORTRAN extended-memory compiler and linker are required.
Additional machines that can run PATRIOT include Digital
Equipment Corporation VAX computers running the VMS oper-
ating system, Prime 50 series computers running PRIMOS, and
UNIX workstations.
Summary
PATRIOT provides an easy-to-use, powerful tool for as-
sessing pesticide leaching potential and developing regional
and local pesticide management plans. The software package
provides access to the most current nationwide databases for
soils, rainfall, pesticide properties, and cropping practices for
major crops. The use of PATRIOT is supported by an on-line
expert help library, and the user is guided in developing the
necessary input for running the PRZM-2 model and selecting the
desired analysis capabilities. The model operates on widely
available PC hardware and is available free-of-charge and
without the burden of run-time licenses.
Literature Cited
1. Goebel, J.J. 1991. Agricultural Chemical Use and the
Potential for Groundwater Contamination: How Big Is the
Problem? Appendix D, Description of the National Re-
sources Inventory. U.S. Department of Agriculture, Wash-
ington DC. Draft Report.
2. Bird, S.L, M.J. Cheplick, R.F. Carsel, and M.J. Fendley.
1991. User's Guide for the PRZM Input Collator (PIC
Version 1.0). U.S. Environmental Protection Agency, Ath-
ens GA. Unpublished Report.
3. Wauchope, R.D., A.G. Hornsby, D.W. Goss, and J.P. Burt.
1990. The SCS/ARS/CES Pesticide Properties Database:
I, A Set of Parameter Values for First-Tier Comparative
Water Pollution Risk Analysis. IN: Pesticides in the Next
Decade: The Challenges Ahead. Virginia Water Resources
Research Center, Blacksburg VA.
4. Mullins, J.A., R.F. Carsel, J.G. Scarbrough, and A.M. Ivery.
1993. PRZM-2, A Model for Predicting Pesticide Fate in the
Crop Root and Unsaturated Soil Zones: User's Manual for
Release 2.0. U.S. Environmental Protection Agency, Ath-
ens GA. EPA/600/R-93/046.
5. Kittle, J.L., Jr., P.R. Hummel, and J.C.Imhoff. 1989. ANNIE-
IDE, A System for Developing Interactive User Interfaces
for Environmental Models (Programmers Guide). U.S. En-
vironmental Protection Agency, Athens GA. EPA/600/3-89/
034.
6. SofSolutions, Inc., Omaha NE.
Notice: The information in this document has been funded
wholly or in part by the U.S. Environmental Protection Agency
under Contract Number 68-CO-0019 to AQUA TERRA Consult-
ants. It has been subject to the Agency's peer and administrative
review, and it has been approved for publication as an EPA
document.
•6U.S. GOVERNMENT PRINTING OFFICE: 1994 - 550-0*7/801*4
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