Transcript Paper - Sanford

Using Environmental Tracers to Help
study areaModel of
CalibrateThe
a Ground-Water
The Middle Rio Grande Basin
Ward Sanford and Niel Plummer
USGS National Research Program, Reston, VA
Doug McAda, Laura Bexfield & Scott Anderholm
USGS Water Science Center, Albuquerque, NM
Information Used to Construct and
Calibrate the Model
• Geologic Information
• Hydrologic Information
• Geochemical Information
• MODFLOW, MODPATH and UCODE
Geologic Information
Geologic Studies were used to Develop
the Model Geometry and Zonation
Geologic
model of the
Middle Rio Grande
Basin constrained by
gravity data (Grauch)
Inner Valley
Alluvium
River Gravels
Ceja Gravels
Layer 1
Layer 2
Medium to
Coarse Sand
Silts
Medium Sand
Fine to
Medium Sand
Eolian Sand
Volcanic Sand
Piedmont Slope
Deposits
Volcanic Flows
Volcanic
Intrusions
Inner Valley
Alluvium
River Gravels
Ceja Gravels
Layer 5
Layer 6
Medium to
Coarse Sand
Silts
Medium Sand
Fine to
Medium Sand
Eolian Sand
Volcanic Sand
Piedmont Slope
Deposits
Volcanic Flows
Volcanic
Intrusions
Rio Grande
alluvium
Layer 1
Layer 1
Fine sand
Paleochannel
sand & gravel
Very fine Sand
Ceja gravels
Proximal
volcanic sand
Northern fluvial
sand & gravel
Northern proximal
volcanic sand
Central fluvial
sand & gravel
Southern fluvial
sand & gravel
Southern proximal
volcanic sand
Central fine &
very fine sand
faults
Rio Grande
alluvium
Geologic
Model
Fine sand
Medium Sand
Paleochannel
sand & gravel
Very fine Sand
Northwest
medium sand
Central
medium sand
Ceja gravels
Proximal
volcanic sand
Northeast
medium sand
West central
medium sand
East central
coarse sand
Northern
medium sand
Northern proximal
volcanic sand
Northern fluvial
sand & gravel
Ground-Water
Southern
proximal
Flow
Model
Central fluvial
sand & gravel
Southern fluvial
sand & gravel
volcanic sand
Central fine &
very fine sand
faults
N
Medium to
coarse sand
scale
0
10
20 km
Southwest
medium sand
Southeast
coarse sand
Piedmont
slope deposits
silts
Extrusive
volcanic rocks
Intrusive
volcanic rocks
Hydrologic Information
Middle
Rio-Grande
Basin
Water Table in 1960
N
Albuquerque
Boundary
Conditions
Jemez Mountain-Front Recharge
and Underflow
Jemez
River
Western Basin
Underflow
Basin
Underflow
Rio
Puerco
Rio
Grande
Middle
Rio-Grande
Basin Boundary
Tijeras
Arroyo
Eastern
Mountain - Front
Recharge
Southwestern
Basin
Underflow
Abo
Arroyo
Rio
Salado
Geochemical Information
Deuterium
Carbon-14
Middle
Rio-Grande
Basin
Boundary
pmC
100
per mil
80
-120
-110
60
-100
40
-90
-80
20
-70
-60
0
-50
Bounda ry
of the
Middle
Rio-Gra nde
Basin
Edge of the
finite-difference
model grid
Albuquerque
Local northwest recharge
Northern MF Recharge
Hagan basin underflow
Jemez underflow
Rio Puerco
Rio Grande
Eastern Mountain Front
Ladron Peak
Abo Arroyo
Basin Discharge
Results
Recharge Estimates
120,000
100,000
Rio Grande
80,000
Acre-feet
per Year
Mountains
60,000
40,000
20,000
0
Kernodle (1995)
Sanford (2003)
Creating a “Trough” with Low Recharge
Western
Recharge
Northwestern
Recharge
River
Water
Northeastern
Recharge
Eastern
Recharge
40 km
Water Levels
For Layer 2
Estimating Paleorecharge Rates
Summary and Conclusions
• Environmental Tracers are an important source of data to
use in addition to geology and water levels to calibrate
regional groundwater models
• Recharge in the Middle Rio Grande Basin is much less
than previously estimated, but was higher in the past.
• The lower recharge rates can explain spatial features in
both the water table and geochemical zones