A Near‐Term Iterative Forecasting System Successfully Predicts Reservoir Hydrodynamics and Partitions Uncertainty in Real Time

• Published in: Water resources research Vol. 56; no. 11
• Main Authors: Thomas, R. Quinn, Figueiredo, Renato J., Daneshmand, Vahid, Bookout, Bethany J., Puckett, Laura K., Carey, Cayelan C.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01-11-2020
• Subjects: Algorithms; Aquatic ecosystems; Coastal inlets; Computational fluid dynamics; Daily forecasts; Data; Data assimilation; Data collection; Drinking water; ecological forecasting; Ecosystems; Ensemble forecasting; ensemble Kalman filter; FLARE; Fluid flow; Forecasting; Freshwater; Freshwater ecosystems; General Lake Model; Hydrodynamic models; Hydrodynamics; Initial conditions; Inland water environment; Iterative methods; Lakes; Mathematical models; Meteorology; Parameter uncertainty; Parameters; Process parameters; Reservoir water; Reservoir water quality; Reservoirs; Root-mean-square errors; Sediment; Sediments; Temperature forecasting; Time management; Uncertainty; Water quality; Water supply; Water temperature; Weather forecasting
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2019WR026138

Freshwater ecosystems are experiencing greater variability due to human activities, necessitating new tools to anticipate future water quality. In response, we developed and deployed a real‐time iterative water temperature forecasting system (FLARE—Forecasting Lake And Reservoir Ecosystems). FLARE is composed of water temperature and meteorology sensors that wirelessly stream data, a data assimilation algorithm that uses sensor observations to update predictions from a hydrodynamic model and calibrate model parameters, and an ensemble‐based forecasting algorithm to generate forecasts that include uncertainty. Importantly, FLARE quantifies the contribution of different sources of uncertainty (driver data, initial conditions, model process, and parameters) to each daily forecast of water temperature at multiple depths. We applied FLARE to Falling Creek Reservoir (Vinton, Virginia, USA), a drinking water supply, during a 475‐day period encompassing stratified and mixed thermal conditions. Aggregated across this period, root mean square error (RMSE) of daily forecasted water temperatures was 1.13°C at the reservoir's near‐surface (1.0 m) for 7‐day ahead forecasts and 1.62°C for 16‐day ahead forecasts. The RMSE of forecasted water temperatures at the near‐sediments (8.0 m) was 0.87°C for 7‐day forecasts and 1.20°C for 16‐day forecasts. FLARE successfully predicted the onset of fall turnover 4–14 days in advance in two sequential years. Uncertainty partitioning identified meteorology driver data as the dominant source of uncertainty in forecasts for most depths and thermal conditions, except for the near‐sediments in summer, when model process uncertainty dominated. Overall, FLARE provides an open‐source system for lake and reservoir water quality forecasting to improve real‐time management.
Key Points
We created a real‐time iterative lake water temperature forecasting system that uses sensors, data assimilation, and hydrodynamic modeling
Our water temperature forecasting system quantifies uncertainty in each daily forecast and is open source
Sixteen‐day future forecasted temperatures were within 1.4°C of observations over 16 months in a reservoir case study