System for Hydromet Analysis, Research and Prediction (SHARP)


SHARP is being designed to facilitate the demonstration and evaluation of variations in the real-time forecasting workflow for short, medium and seasonal range streamflow predictions. To date, it has centered on forecasting in selected medium-sized basins in the continental US. As the figure below illustrates, the philosophy behind SHARP recognizes that model-based streamflow forecasting depends critically on not only the hydrologic and associated models (e.g., river routing), but on a range of key methods and datasets including meteorological analyses, downscaling of weather and climate forecasts, model parameter estimation (ie, calibration), data assimilation, post-processing, and a robust capacity for verification and diagnostic evaluation.

SHARP system schematic


The Department of Interior Bureau of Reclamation (Reclamation), the U.S. Army Corps of Engineers (USACE), and the National Center for Atmospheric Research (NCAR) are partnering to evaluate: (1) the application of state-of-the-science forecasting methods and datasets in an experimental real-time operational platform serving a selection of watersheds across the contiguous U.S., and (2) the performance these methods and datasets in ‘over-the-loop’ forecasting. The first objective is motivated by a lack of experience with various advanced methods (such as data assimilation), implemented in an integrated operational workflow. The second objective is prompted by a perceived need to adjust parts of the current operational forecasting workflow in order to realize fully the benefits of various advanced or alternative methods in streamflow forecasting and water management support. A central hypothesis of this project is that over-the-loop forecasting will help unlock the potential of advanced forecasting methods to inform water resources management, yet there has been insufficient real-time, publicly available testing, demonstration, and evaluation of over-the-loop forecasting from the perspectives of workflow feasibility, product delivery reliability, and forecasting skill. This work is intended to help fill these gaps and further enhance and inform the methods that are being evaluated.


The SHARP system is being designed to produce retrospective and real-time streamflow forecasts:

  1.   Ensemble short-to-medium range (to 15 day) streamflow forecasts. 
  2.   Seasonal probabilistic runoff forecasts of the type used in water supply management in the western US.

The initial phase of this work has focused on individual catchments, and will next shift toward regional implementation over several pilot domains (e.g., the Pacific Northwest).


Andy Wood (NCAR, PI) and Bart Nijssen (U. Washington, Co-PI)


Funding and guidance for the project are primarily provided by the Bureau of Reclamation and the US Army Corps of Engineers, with additional funding support from NOAA.

This product has a project page. See more details here.