Transcript Nutrient and Pesticide Accounting in the Chipola River/Floridan Aquifer System—Update This Study Jointly Funded by U.S.

Nutrient and Pesticide Accounting in
the Chipola River/Floridan Aquifer
System—Update
This Study Jointly Funded by
U.S. Geological Survey
and
Florida Department of Environmental Protection
Presented by
Rick Hicks of FDEP
And Christy Crandall of USGS
STUDY OBJECTIVES
• Identify significant nutrients and pesticides inputs to the Chipola
River/Floridan aquifer system using existing information
• Characterize the hydrologic and geochemical processes occurring along
flowpaths using a groundwater flow and tracking model and a
geochemical model along flow paths.
• Test 1 or possibly 2 hypothetical scenarios—tracking nitrate and maybe
an organic compound to the Jackson Blue Spring and the Chipola River.
• Provide a model that will assist in predicting spring and ground water
impacts from land use modifications
BACKGROUND
Study
Area
Location
Chipola Watershed
Floridan Aquifer System
• Vertically contiguous thick sequence of
limestone and dolostone of late
Paleocene to early Miocene age
• Highly potable--drinking water is derived
from Floridan aquifer system
• Contains numerous springs, sinks and
other karst features—highly vulnerable.
The Floridan
Aquifer and the
Chipola
River Basin
•Recharge occurs mainly in
unconfined and semi-confined
areas
•Potentiometric surface—
flows southward from northern
extent
The Floridan
Aquifer and the
Chipola
River Basin
• Ground water makes up the
majority of the Chipola River's
discharge during low and
medium flow conditions
•At least 63 springs
identified(Barrios and
Chellette, 2004)
• Higher nitrate concentrations and more
occurrances of nitrate and pesticides in
the Chipola River and Floridan aquifer in
this area than in other areas of the
Floridan aquifer system (U.S. Geological
Survey data).
Progress
1) Acquired and compiled existing
data
2. Selected and sampled field
parameters, NO3, and E.Coli at
contributing springs and in the
Chipola River (57 sites total
sampled)
Preliminary
Nitrate
Results in
mg/L as N
Preliminary
E.Coli.
Results
In count
per 100 ml
3. Used preliminary data to target 3
flowpaths and obtained permission to
sample wells within these flowpaths:
-2 flowpaths were selected for
nutrient issues
- 1 flowpath was selected for E.Coli
4 ) Sampled 3 wells along each
flowpath for major ions, nutrients,
age tracers, isotopes, pesticides,
pharmaceuticals, field parameters
The 3 Selected
Flowpaths
With preliminary
NO3 in mg/L as N
From all data and
networks
-most flowpath
data is not back
from the lab yet.
4. Continue to build and calibrate a
ground-water flow and particletracking model for the Floridan
Aquifer/Chipola River system
—progress
¹
Legend
flurbspol polygon
boundary
Existing
Finite
meshcl2_polygon
Element
Groundmodgrid1_polygon
water Flow
Model
fldnext_84 arc
Boundaries (2)
Tallahassee
New MODFLOW
based Groundwater Flow Model
Boundary
0 10 20
40 Kilometers
GW Flow Model is built in MODLFOW using
the following data and parameters
from Finite element Model:
•
•
•
•
•
•
•
Hydraulic parameters
Aquifer tops and bottoms
Pumping data
Recharge
Boundary conditions
River stage and parameters
Starting heads
Model Currently running in MODLFOW but
still needs work:
• Boundary conditions are not working
properly yet.
• Currently working on this as Rick is giving
this talk.
• Will have to adjust parameters from old
model during calibration.
Timetable
• Model calibration completed by 12/07
• Particle tracking along flowpaths hopefully
completed by 03/08