Evaluation of the Enhanced Snowmelt Runoff Model to Assist in Water Management Operations and Decision Support
The need to accurately predict snowmelt runoff for the numerous and often competing water uses that Reclamation delivers water for has never been greater. Improved daily streamflow forecasts are needed to assist Reclamation operations to efficiently manage reservoirs and deliver water to the numerous users. With a greater degree of climatic variability, including winter snowfall and spring precipitation, improved streamflow models are needed.
This project would focus on evaluation of recently developed technologies to improve the predictability of streamflows based on short-term to medium length downscaled weather forecasts to assist Reclamation's decisionmaking and management of water. Reclamation will collaborate with the Natural Resources Conservation Service (NRCS) and private industry to calibrate and run the enhanced Snowmelt Runoff Model (SRM) for five basins starting in the 2011 runoff season.
Five basins in the Snake River basin were selected, using considerations of climatic variability, rain and snow (which influence snowmelt runoff), past research by the University of Idaho, and headwater streams in primarily snow dominated basins. The enhanced model uses National Aeronautic and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS ) data, improved snow probability mapping algorithms to see under clouds, and downscaled 15-day weather forecasts for NRCS's Snowpack Telemetry SNOTEL) sites. The use of satellite snow covered images provides the input variables of the receding snow covered area in the basin not monitored by NRCS's SNOTEL network to improve the accuracy of predicting daily streamflows and timing of snowmelt runoff. This enhanced SRM model could be implemented and expanded in other Reclamation projects to assist in water management. Anuik Consulting has the expertise with the model, as they were the primary developers of the enhanced model while completing their degrees at the University of Idaho from 2002-2007.
Need and Benefit
Over 80 percent of the water supply in the Western U.S. results from the melting mountain snowpack. Many local, State, and Federal agencies depend on knowledge of the runoff from the mountains, including those interested in agriculture, power generation, tourism, and fire prediction. Accurate streamflow forecasts are critical in the Western U.S., where our annual water supply falls as snow and the warm, dry summers provide ideal growing conditions for irrigation agriculture. Irrigation is critical in the U.S., as nearly half the value of all crops sold comes from the 16 percent of harvested cropland that is irrigated. Four government agencies, which include Reclamation, the U.S. Army Corps of Engineers (Corps), NRCS, and the National Weather Service (NWS), each forecast and coordinate streamflow forecasts to help manage this critical natural resource in the West that is highly depended on the amount of snow that accumulates in the mountains of the West.
Reclamation and water resource managers require accurate and timely predictions of water supplies and demands to manage water in high runoff years and allocate when resources are limited to meet complex and often competing demands for water. Accurate estimates and forecasts of snow cover extent, snow water equivalence, and snowmelt are important for efficient short- and long-term management of water in both low runoff years and high runoff years. Through sound science, these products are now available to incorporate into streamflow models to improve streamflow forecast results. There is a critical need by water resource managers, including Reclamation and NRCS, for improved short-term to seasonal water supply. These forecasts would help management of this natural resource and benefit both agencies in meeting their mission while helping their customers who deliver to the users, and managers that include farmers and irrigators, hydropower producers, and fish and wildlife.
The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.
Enhanced Snowmelt Runoff Model Scoping and Literature Progress Report 2011 (final, PDF,
By Mr. Brian Harshburger
Publication completed on September 28, 2011