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United States Department of Agriculture

Agricultural Research Service

Research Project: Application of a Physically-Based Distributed Snowmelt Model in Support of Reservoir Operations and Water Management

Location: Northwest Watershed Management Research

2013 Annual Report


1a.Objectives (from AD-416):
This project will focus on the Bureau of Reclamation’s need for hydrologic modeling tools that can optimize reservoir management decisions to improve planning and management of water supplies. The latest advances in snow accumulation and melt modeling, much of it developed at the USDA-ARS Northwest Watershed Research Center, will be applied to the Boise River Basin. There are three large reservoirs in this stretch of the Boise River. This will be the first application of a physically-based distributed snow model in an operational forecasting setting. We will assess the suitability of these modeling tools to operational needs and evaluate their performance against currently available streamflow products.


1b.Approach (from AD-416):
Stage one will be the application of Isnobal, a physically-based distributed snow model, in an operational setting - the Boise River Basin. The model will be forced with currently available data including meteorological stations operated by the Natural Resources Conservation Service, Reclamation, and Sawtooth National Forest Avalanche Center. Simulated snowcover will be evaluated against satellite-derived observations and melt inputs will be compared to measured discharge. All modeling will be conducted at the USDA-ARS Northwest Watershed Research Center in Boise, ID. Updated maps of SWE and snowcover energy state will be repeatedly transferred to Reclamation. The sensitivity of the simulations to gaps in data availability will be evaluated and recommendations for additional instrumentation made.

In stage two Isnobal will be coupled to a soil storage or routing model in order to convert Isnobal-simulated surface water inputs to stream discharge. Additionally, the feasibility of ingesting short-term weather forecasts to produce predictions of reservoir inflows will be assessed. Prior research initiatives have successfully coupled Isnobal with routing models spanning a range of complexities to model streamflow. We will investigate the appropriateness of these prior couplings as well as other routing models for operational applications. Once coupled, predicted streamflow will be evaluated against observations. Available short-term weather forecasting products will be evaluated for compatibility with Isnobal modeling requirements.

Stage three will be a proof of concept of the abilities of the coupled Isnobal-routing model to forecast short-term (1 - 3 days) reservoir inflows. Short-term weather forecasts will be manually input to the coupled model. At this stage, it will also be possible to adjust forecasted temperatures, precipitation, and cloud cover in order to simulate flows for a range of conditions centered on the most probable forecast. Predicted inflows will be provided as a test product to Reclamation and other interested parties. Simulated inflows will be evaluated against other forecasting products and observations.


3.Progress Report:

This cooperative agreement was established to assist Bureau of Reclamation's need for hydrologic modeling tools that can optimize reservoir management decisions to improve planning and management of water supplies. In FY2013, the Isnobal snow model was set up and run in near real-time for the Boise River Basin. Set-up included the creation of automated routines to retrieve meteorological observations from 18 sites, to spatially distribute these data to generate model forcings, and ultimately run the Boise River Basin snow simulations and create desired outputs. From the beginning of April through early June the snow model was updated on a weekly basis. After each update, maps and graphs of the Snow Water Equivalent and snowmelt data were electronically transferred to the Bureau of Reclamation’s Boise offices. Analysis of the FY2013 work is currently being conducted to further improve the modeled products. This agreement was established in support of objective 3 of the in-house project, the goal being to expand integrated snow hydrology modeling to larger scales, coupling to belowground processes, including wind effects on precipitation input, and helping to incorporate snow-related processes into ARS watershed and management simulation models (e.g., SWAT, AnnAgNPS, KINEROS, AgES, AGWA, RHEM, ISNOBAL, PIHM, etc).


Last Modified: 8/29/2014
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