Hydrothermal Modeling for Lay Dam, Coosa River (AL, USA)

The Coosa River is one of the most developed rivers in Alabama. The river is used for recreation, drinking water, power generation, agriculture and timber. One section of the Coosa River between Logan Martin and Lay dams is the Lay Lake which was impounded by one of the earliest concrete dams in the US. Thermo- and hydrodynamics of this lake are strongly governed by the operation of the hydropower plants at the Logan Martin and Lay dams and Ernest C. Gaston thermal power plant. Therefore, the investigation of thermal and hydrodynamics of this lake is very important to ensure the effective power generation and environmental protection.

To assist Alabama Power for effective and environmental sustainable power generation for the Lay Lake, Dynamic Solutions, LLC has been conducting a numerical modeling and investigation of thermal and hydrodynamics of the lake using the Environmental Fluid Dynamics Code (EFDC) Model. The model has been setup for the main channel and embayments of the Coosa River between the two dams using a curvilinear orthogonal grid and takes into account hydrodynamic and hydrothermal processes as well as meteorological forcing of winds, sun radiation and evaporation. Model boundary conditions are flow and temperature data of the water released from the dams and operational data of the power plants.

The model has been calibrated using intensive data of ADCP flows, water levels and water temperature collected in the period from July to September 2010. The model results help to assess the existing system hydrodynamic and hydrothermal conditions to match the environmental standard. Important hydrodynamic and hydrothermal phenomena such as reversal flows from hydropower operations and cooling water recirculation have been revealed which will help to improve the operation of the power plants.