Location: Northwest Watershed Research Center
Project Number: 2052-13610-012-026-I
Project Type: Interagency Reimbursable Agreement
Start Date: Sep 29, 2017
End Date: Jun 30, 2021
The objective of this agreement is for Agricultural Research Service (ARS) to integrate spatial snow data derived from NASA’s Airborne Snow Observatory (ASO) into operational runoff forecasts. Utilizing iSnobal, a physically-based snow model, near real-time snow simulations will be developed for the San Joaquin watershed and maintained throughout the snow season. iSnobal model will be updated with ASO data when available and will periodically use short-term weather forecast models to generate short term snowmelt forecasts. The modeling system for taking meteorological station data or weather forecasts, distributing the data, and running the models will be transferred to Reclamation for usability testing. This is the first major step towards having Reclamation running the models, producing water supply forecasts, and having the output data available to other partners. These actions will help achieve the goal of advancing runoff forecasting for the San Joaquin River and Millerton Reservoir, serving as a model for other watersheds in the Sierra Nevada and throughout Reclamation. This project is part of a larger body of work investigating using ASO data and physically based snow models in pursuit of a 21st century vision for hydrologic monitoring and decision support information. Contributors include the USDA Agricultural Research Service, NASA Jet Propulsion Laboratory, California Department of Water Resources, Pacific Gas & Electric, Southern California Edison, South Valley Water Association, and Friant Water Authority.
ARS will construct and maintain a model of the San Joaquin Watershed in the snowpack modeling environment of iSnobal. Simulations will be run from October through July, tracking the accumulation of snow depth, snow density, sublimation, and melting. Spatial snow data from NASA’s Airborne Snow Observatory (ASO), typically collected monthly, will be used to update the model state – improving model accuracy. iSnobal model output will be available on a weekly basis during snowmelt season. Additionally, a small adjacent sub-basin, the Lakes Basin, will be modeled as a calibration tool to take advantage of ample ground-based sensors, with the same reporting schedule. ARS will develop a prototype modeling system that will produce a water supply forecast. This will involve taking meteorological station data or a short term forecast, distributing the data to the modeling domain (San Joaquin), and running the model. The model results will be analyzed to produce a water supply forecast. This activity transfers the product to Reclamation for usability testing and is the first step in running physically based models for operational use. This will eventually allow USBR to operate the model itself and ensure the modeling system is robust for broader use by CA Dept. of Water Resources and other partners. Reclamation will be involved continuously in the development to ensure the product meets expectations.