Skip to Main Content U.S. Department of Energy
Waterpower banner

Advancing Modeling Tools For Assessment of Long-Term Energy/Water Risks for Hydropower

According the DOE report titled Energy-Water Nexus: Challenges and Opportunities there is a need to explore the potential risks climate change may have on complex energy, water, and land system interactions. Of specific interest is the relationship between and potential future risks regarding the following:

  • changing water temperature regimes in rivers;
  • electric power generation from hydropower, thermoelectric plant cooling, and discharge; and
  • water-quality and habitat needs for sensitive species

To better evaluate and address the future risks facing hydropower, PNNL, funded by the Department of Energy's Water Power Technologies Office in fiscal years (FY) 2017-2019, is working to provide a scalable, fine-resolution, physics-based modeling framework. This modeling framework will equip decision makers with the capability to model potential likelihood and severity of instream flow changes and water-temperature events under a range of possible future climate scenarios. Based on model outputs, decision makers will be able to evaluate alternative operations and infrastructure investments to mitigate risk.

Initial development and demonstration of the modeling framework will be based off a portion of the greater Columbia River Basin (FY17). Once results from the initial basin are interpreted (FY18), the project will move to a different basin to validate the framework (FY19) while continuing to look at the impacts of altered climate on future hydropower development scenarios in the initial basin as described by the DOE's Hydropower Vision project (FY19).

The modeling framework will be developed through the following set of interrelated components:

Stakeholder Engagement

Columbia River

The first step in developing a modeling framework is to engage decision makers and understand the specific requirements and thresholds they have for making their decisions. This effort will generate a user needs assessment, and will culminate in three stakeholder groups (one national, and one in each test basin). Knowledge gained from stakeholders will inform the entire modeling framework development and application process.

National Committee Meeting, June 2017

Point of Contact:

Climate Modeling

Climate Modeling

A holistic approach will be implemented to consider the uncertainty of climate forecasts on tributary inflows and water temperature. We will leverage our ongoing work using a hybrid downscaling approach in which the regional Weather Research Forecast model is used to dynamically downscale five Global Climate Model (GCM) scenarios to 6-km resolution in the regions of interest. Applying the hybrid downscaling approach will provide high-resolution climate scenarios that bracket the impacts of different carbon-reduction pathways and GCM uncertainties.

Point of Contact:

Watershed Modeling

Watershed Hydrologic Modeling

Water temperature at the plant scale or within headwater tributaries requires analysis at much finer spatial scales than what is typically used by semi-distributed hydrologic models. To achieve the resolution necessary for decision makers, we will employ the Distributed Hydrology Soil Vegetation Model (DHSVM). DHSVM has a physics-based capability to simulate spatially distributed hydrology and water temperature over a stream network at high time and space resolutions, and can also represent topographic and riparian shading effects on stream temperatures.

Point of Contact:

River and Reservoir Water Quality Modeling

River and Reservoir Water Quality Modeling

In a river basin, water-temperature and water-quality requirements are truly a multi-scale problem that can best be addressed using a collection of models, of appropriate dimensionality and scale, linked as a hybrid system. The PNNL modular aquatic simulation system 1D (MASS1) unsteady hydrodynamic and water-quality model has been applied in the Columbia River and can meet the basin-scale need. DHSVM will supply inflows and associated water temperature to the MASS1 model to simulate the upper sub-basins and route flow to the mainstem and impounded rivers. MASS1 then simulates watershed channel flows, mainstem flows, water temperature, and reservoir operations including hydropower production. In areas not affected by reservoirs, but where understanding lateral variation in velocities and temperature are required, a 2D depth-average model (MASS2) will be applied. A thermal power plant module will be included with river-reservoir codes to evaluate the quantity of water withdrawn and the quantity and temperature of water returned to a river. The framework will be structured to accommodate other numerical models provided they are technically acceptable and open source.

Point of Contact:

Biological and Habitat Assessments

Biological and Habitat Assessments

The modeling framework will also help decision makers evaluate potential climate variability impacts on tributary and mainstem flows, water temperature, and suitability for species and habitats of concern. For example, in the Hanford Reach of the Columbia River, velocities, water depths, and temperature are affected by operation of the upstream Priest Rapids Dam which in turn can impact fish habitat. Cool water releases from dams, particularly Dworshak Dam, are one management option to help lower late summer water temperatures in the downstream reaches of the Lower Snake River. The Columbia River estuary offers another case to analyze the effects of the upstream power system on water temperatures downriver of a dam regulated for sensitive aquatic organisms. The water temperature, timing and magnitude of flow upstream of Bonneville Dam affects temperature in the critical shallow-water habitats in the downstream floodplain. In collaboration with Portland State University, PNNL will utilize the widely applicable Delft3D model to quantify changes in habitat suitability for salmon and other sensitive species in conjunction with regression models.

Point of Contact:

Future Hydropower Development

Future Hydropower Development

In addition to existing hydropower and thermoelectric power plants, the modeling framework also will be used to evaluate how the deployment of new hydropower will impact river basins under altered climate scenarios. Future hydropower developments described by the DOE Hydropower Vision will be applied to the Columbia River Basin, allowing for detailed site-specific impacts analysis of future hydropower construction in and beyond the Basin.

Point of Contact:

Water Power Research