The Predictability of Streamflow in U.S. Watersheds
The overarching goal of this project is to identifying and prioritize the research necessary to improve improve hydrologic monitoring and prediction products in response to user needs.
The US Bureau of Reclamation (Reclamation) and the US Army Corps of Engineers (USACE), in collaboration with the US National Weather Service (NWS) recently assessed the use of weather and hydrologic forecasts for short-term water management. The resulting report -- Short-Term Water Management Decisions: User Needs for Improved Weather and Climate Prediction Information (or ST Doc) -- identified gaps related to better use of weather, climate, and hydrologic information (i.e. monitoring and forecasts) in short-term water management decisions. Short-term decisions in this case are those associated with look-ahead periods of generally 1 year or less. Among other elements, the ST Doc described how different weather and hydrologic information products are used to support different water management decisions.
As a first step toward addressing the identified needs, NCAR is undertaking a comprehensive predictability assessment to quantify and document the major sources of skill and uncertainties in hydrologic monitoring and prediction products, and to investigate the potential for current state of the art datasets and techniques to reduce these uncertainties. In particular, the project will quantify the impact of different sources of uncertainty on different types of forecasts (e.g., 1-day stage forecasts, 3 month volume forecasts), at different forecast initialization times throughout the year (e.g., forecasts initialized on October 1st versus April 1st), and in different hydroclimate regions (e.g., regions with/without substantial snow storage; regions with varying degrees of climate predictability). Integrating the USBR-USACE assessment of user needs with an assessment of the opportunities to improve hydrologic prediction products will provide a foundation for identifying future research and development priorities.