Thermal Discharge Modeling in Mobile River
using 3D Hydrodynamic Model EFDC
Janesh Devkota and Dr. Xing Fang
Department of Civil Engineering, Auburn University
Dr. William Garrett and Jonathan Ponstein
Alabama Power Company
September 7-9, 2011
2011 Alabama Water Resources Conference
Presentation Outline
• What is EFDC ?
• Why EFDC over other popular models such as
UNTRIM, DELFT 3D and MIKE 3D ?
• Area of applications of EFDC
• EFDC software
EFDC
• Model site
• Model setup
• Results
• Calibration
• Future climate scenario and sensitivity analysis
Environmental Fluid Dynamic Code - EFDC
Overview
• The EFDC model is surface water modeling
system that incorporates fully integrated
hydrodynamic, water quality and sedimentcontaminant simulation capabilities.
• EFDC is extremely versatile and can be used for 1,
2, or 3-dimensional simulations of rivers, lakes,
estuaries, coastal regions and wetlands.
• The single source code implementation eliminates
the need for linking multiple models to arrive at an
effective modeling solution.
EFDC Development History
• Developed at the Virginia Institute of Marine
Science (College of Wm. & Mary) with primary
support from the state of Virginia.
• Presently maintained by Tetra Tech, Inc. with
ongoing development support from the US EPA
ORD (Office of research and development), OST,
and regions 1&4
• Currently used by federal, state and local agencies,
consultants, and universities.
Why EFDC was chosen over other models?
Boundary
EFDC
UNTRIM
DELFT
MIKE3
Flow
*
*
*
*
Open
*
*
*
*
Hydraulic Structures
*
Jet Plume (Near
Field/Far Field)
*
Withdrawal/ Return
*
•Unlike other models, EFDC has some extra features to include
the boundary conditions such as hydraulic structures, jet plume
(near field/ far field) , withdrawal/return flow.
•EFDC is a hydrodynamic model used by EPA.
• Several Thermal Discharge Applications done successfully
in various studies.
EFDC Thermal Discharge Applications
• Analysis of temperature in Conowingo Pond as influenced
by the Peach bottom Atomic Power Plant thermal
discharge.( Conowingo Pond)
• 3D numerical simulation for flow and heat transport of
power plant affected by tide (nuclear power plant in
Haiyang in Shandong Province, China)
• Development of an Ecohydraulics Model to evaluate the
impacts of water withdrawals on estuary. (Homosassa River
in Florida )
• Development of temperature criteria for marine discharge
from a large industrial seawater supplies project in Western
Australia (Burrup Peninsula in Western Australia)
EFDC Software (EFDC Explorer)
EFDC Explorer is a
pre-processing and
post processing
software that would
help setup EFDC
model and analyze
the results.
The model is developed by
Dynamic Solutions and I
would like to acknowledge
Dynamic Solutions for
making the web version
free.
Study Site: Barry Power Plant
• The simulation domain of the
model is a segment (about 16.0
river miles) of the Mobile River
between upstream, 10 km
upstream of Bucks USGS
station and downstream, the
intersection of Mobile River at
Interstate 65 Bridge.
• Barry Power Plant is operated
along the Mobile River near
Bucks which has the tidal
effects at downstream from the
Gulf of Mexico
• The model created using EFDC
will be referred as Barry
Model.
Mobile River
Highway 65
James M. Barry Generating Plant
Data Requirements
• Determine the type of model application (e.g.
dimensionality, time dependency, and state variables)
• Set up inputs to drive the model (e.g., bathymetry,
weather data, external loadings, inflows, and open
boundary conditions.
• Provide a basis for adjusting model parameters
(model calibration).
• Evaluate if the model adequately describes the
waterbody (model verification).
Key Processes in Barry Model
• Withdrawal of water at the intake canal and return of
the flow at the discharge canal near the Barry Power
Plant.
• Stratification in the river.
• Tidal effects from Gulf of Mexico.
• Atmospheric interaction (wind, air temperature, solar
radiation, etc.)
Model Set Up
• Orthogonal curvilinear coordinate system was used.
• Computational grid has 1926 active horizontal cells
and 6 horizontal layers in the vertical direction.
• Time step of 5 seconds was used to satisfy CFL
(Courant- Freidrich-Levy) condition.
• Initial conditions: water depths, flow velocities,
water column and bed temperatures.
• Depths based on bathymetry data, velocities were set
to zero at beginning of simulation.
• Water column and river bed temperature were
initialized to 25 ⁰C.
• Bottom roughness height of 0.02 m was used.
Grid for the Barry Model
Intake canal
Barry Location
Discharge canal
Total no of intake cells = 150
Total no. of discharge cells = 59
Total No. of volume cells = 1926*6 = 11,556
Min (m)
Avg (m)
Max (m)
Dx
9.3
38.7
74.3
Dy
10.4
63.3
377.9
Grid Overlapped on Map
Intake canal
Discharge canal
Boundary Conditions
Upstream boundary
• Flow boundary
• Temperature boundary
Downstream boundary
• Elevation boundary
• Temperature boundary
Meteorological Input
Wind speed,
solar radiation,
and air
temperature are
major
meteorological
inputs for
modeling the
temperature in
the rivers.
Fair hope Station
&
Jay Station
(FAWN)
Withdrawal and Return in Barry Model
Mobile River
Intake Canal
Intake Canal
4 and 5
Withdrawal Location
Discharge Canal
1 and 3
Return Flows
Mobile River
Discharge Canal
Calibration
• Water surface elevation, flow velocities, and
temperature were simulated using EFDC
model
• The calibration was done for elevation,
velocity, and temperature on several locations.
Calibration Stations
Upstream
St 3
St 4
St 5
St 6
Mobile River
Downstream
Zoomed to show calibration Stations
near intake and discharge canal
USGS/APC Bucks Station
Bucks
Mobile
River
Temperature Calibration at Discharge and Intake
Mixing Zone Calibration
Vertical Temperature Profile Calibration
Temperature Calibration at C1, C2, 1, 2, 3 & 4
Temperature Calibration at Station 5, 6, and 7
Station 5
Station 6
Station 7
Sensitivity Analysis
• Various sensitivity scenarios were tested for the
Barry Model.
1. Half the inflow
2. Double the inflow
3. Downstream 1 ft increase
4. Downstream 3 ft increase
Graphs For Sensitivity Analysis
- For the half inflow scenario, temperature is more than the base case
- For the 3 ft increase downstream, the temperature variation is higher
than base case.
Future Climate Scenario
• Canadian Climate Center (CCC) GCM model was used to predict the future
climate scenario: Air temperature and solar radiation are predicted to
increase while wind speed slightly decreases.
Projected Changes from CCC GCM
There is slight increase in temperature in mixing zone under the
future Climate Scenario.
Summary and Conclusion
• Barry model was developed using three dimensional
EFDC (Environmental Fluid Dynamics Code) model.
• Flow boundary, elevation boundary and withdrawal
and return boundary were used.
• Model was successful in estimating the flow and
temperature variations from the observed historic data
of 2010.
• Sensitivity study was done to understand the impact
on temperature under various cases such as surface
elevation rise in downstream, half inflows, and future
climate conditions.
THANK
YOU
Questions ?