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 ?