Technical Support for the Tennessee Valley Authority

The Tennessee Valley Authority (TVA) pursues its mission to improve the lives of the people of the valley by providing affordable electricity along with environmental stewardship. TVA manages more than 40 dams and three nuclear power facilities in the Tennessee Valley, with dam safety and risk mitigation being critical aspects of its mission. The organization also handles land management for the Tennessee River system, assisting local power companies and state and local governments with economic development.

TVA River Management is responsible for providing power for more than nine million people in Alabama, Georgia, Kentucky, Mississippi, North Carolina, Tennessee, and Virginia, as well as the operation of the reservoir system to meet flood control and navigation needs. The TVA Dam Safety program mitigates risks related to extreme flooding, dam operations, and dam failures.

Facing such a daunting list of crucial responsibilities, the TVA relies on collaboration with proven partners to ensure the safety of its constituents and the protection of energy and environmental resources.

Pursuing Operating Policy and Operational Forecast System Enhancements

Our Water Resources Management Division, formerly the consulting division of Riverside Technology, Inc., has been working with TVA since 2002. We provide the organization with tools and analyses that are relevant to the modernization of climate, weather, and water services for the region.

Our first project was to assess how modification of TVA’s reservoir operating policies would impact flood risk, hydropower revenues, navigation, water supply and quality, and recreational activities across the Tennessee River watershed. We performed reservoir modeling and flood frequency analysis for 36 reservoirs within the Tennessee basin using the University of Colorado’s RiverWare® river basin model system. Through our work, TVA identified a variety of modifications to their previous operating policy that allowed better use of the available water resources.

TVA also sought support when it came to enhancing its operational forecasting responsibilities, which include data collection and quality control, hydrologic and hydraulic modeling, reservoir operation simulation and optimization, and hydrothermal modeling. In 2012, TVA determined to upgrade their current forecasting system to the Delft Flood Early Warning System (FEWS) platform. We assisted in the upgrade by incorporating improvements to their operational rainfall estimation processing and configuring hydrologic models for a subset of the TVA system within the FEWS framework.

As a result of the success of the pilot FEWS implementation, TVA engaged us to lead the transition of the remainder of their operational forecasting system to the FEWS platform. In addition, we integrated the RiverWare optimization model with FEWS and implemented hydraulic models. Our team also applied tabular, graphical, and spatial displays to support TVA’s decision-making.

An important aspect of TVA’s forecast system modernization involved the development of improved hydrologic and hydraulic models. We coordinated with TVA and the National Weather Service to complete the calibration of the models, which now better simulate natural flows in the system compared with the legacy models. Now, the organization has access to more accurate forecasts of reservoir system inflows that will allow for improved release planning by the TVA river schedulers.

Bolstering TVA’s Emergency Management and Risk Mitigation Capabilities through Future-Looking Projects

Our team provides essential support and analyses to improve TVA’s emergency management tools and risk mitigation as well. From 2013-2015, we provided Emergency Action Plan inundation mapping using HEC-RAS and GIS mapping tools to produce updated inundation maps for the postulated failure of 40 dams. The hydraulic model incorporated information from more than 30 existing models or sources, resulting in a comprehensive hydraulic model that encompasses more than 1,900 river miles and every major reservoir in the TVA system.

We are also leading two major efforts at TVA to provide better risk quantification. First, we are calculating consequences for hypothetical failures through improved HEC-RAS and HEC-FIA models and mapping toolsets to develop life loss and economic consequence for twelve TVA dams. Second, we are quantifying hydrologic hazards (i.e., flood exceedance probabilities) through development of precipitation-frequency relationships and a framework to generate hydrologic hazard curves throughout the TVA reservoir system in support of the Dam Safety program. By calculating finer resolution and more accurate risk information, TVA has valuable tools to make decisions related to major capital improvement projects, the sufficiency of their current operating policy, and allocation of resources.

Looking to the future, we are also working with the TVA to update probable maximum precipitation and flood estimates and assisting in evaluating and improving forecast verification. Our team is also evaluating 3-D modeling tools, improving system-wide hydrothermal modeling, and updating forecast tools for TVA’s three nuclear facilities and multiple coal plants.

With these and other potential projects, we intend to continue our longstanding collaboration with TVA to provide a wide range of river management services across several mission-critical operational areas.