4/
7/
04
1
A
Varying
Volume
Water
Body
Model:

Testing
and
Evaluation
Marietta
Echeverría
Office
of
Pesticide
Programs,

Environmental
Fate
and
Effects
Division
4/
7/
04
2
PE4
Shell
 
Launches
PRZM
 
Launches
EXAMS
RRA
Shell
 
Launches
PRZM
 
Launches
VVWM
EXAMS
 
Constant
volume
 
Monthly
parameter
value
variation
VVWM
 
Volume
varies
 
Daily
parameter
value
variation
PRZM
Output
File
PRZM
Output
File
Level
II
v
1.0
Level
II
v
2.0
PRZM
PRZM
Input
File
PRZM
Input
File
4/
7/
04
3
QA/
QC
Testing
°
Tested
RRA
shell
for
launching
PRZM
against
the
PE4
shell
°
Ran
all
crop
scenarios
with
RRA
shell
°
Compared
the
VVWM
dissipation
processes
with
EXAMS
°
Verified
the
VVWM
volume
and
overflow
4/
7/
04
4
EXAMS
and
VVWM
Comparison
°
FL
sugarcane
and
CA
almond
crop
scenarios
°
Short­
lived
ChemA
and
longlived
ChemB
°
"
Standard"
ecological
surface
water
modeling
scenario
4/
7/
04
5
Surface
Water
Modeling
Scenarios
100
n.
a.

Minimum
volume
(
m3)
30,000
n.
a.

Maximum
volume
(
m3)
20,000
20,000
Initial
volume
(
m3)
0.01
n.
a.

Minimum
depth
(
m)
3
n.
a.

Maximum
depth
(
m)
2
2
Initial
depth
(
m)
1
1
Surface
area
(
ha)
10
10
Drainage
area
(
ha)
PRZM/
VVWM
PRZM/
EXAMS
4/
7/
04
6
CA
Almond,
ChemA
4/
7/
04
7
CA
Almond,
ChemB
4/
7/
04
8
FL
Sugarcane,
ChemA
4/
7/
04
9
FL
Sugarcane,
ChemB
4/
7/
04
10
Summary:

QA/
QC
Testing
°
RRA
shell
consistent
with
PE4
°
RRA
shell
compatible
with
crop
scenarios
and
metfiles
°
VVWM
dissipation
processes
consistent
with
EXAMS
°
VVWM
volume,
overflow
and
hydrologic
washout
verified
4/
7/
04
11
Summary:

EXAMS
and
VVWM
Comparison
°
Varying
volume
water
body
significantly
effects
EECs
due
to
dilution,

evaporation
and
dissipation
due
to
hydrologic
washout
°
Dissipation
due
to
washout
can
be
dominant
process
°
Standard
modeling
scenario
may
not
be
appropriate
for
all
crop
scenarios
