In this Section:

	Background
	Project Overview
	Research Methods
	Status of Project
	References
	Related Links
	Contacts

Photo by: Lynn Betts
USDA NRCS

Research and Products:
Snow Cover Mapping

Project Overview

From its inception, the CLIMAS research agenda regarding snowpack has relied on feedback from a wide variety of stakeholders, including, among others, the Salt River Project, state engineers from New Mexico and Colorado, and the California Department of Water Resources. They use snowpack information to make management and planning decisions about their specific operations. In a workshop with researchers, stakeholders expressed their dissatisfaction with the data currently available, stating that point data on snow water equivalent were not sufficient to meet their objectives.

Originally, data from national Snow Telemetry (SNOTEL) stations provided a simple index of spring runoff. The relatively long historical record of such data has been used to develop empirical models that generate springtime runoff forecasts based on wintertime SNOTEL snow water equivalent values. However, since the skill of these models decreases substantially during extreme climatic conditions—such as droughts and floods, which are anticipated to increase due to global climate change—SNOTEL data may become less useful. Therefore, ongoing research focuses on deriving forecasts using hydrologic models that consider the spatial variability of snowpack. The use of these models is especially important for forecasting runoff during unusual climatic conditions and for simulating streamflow under different climate change scenarios.

In order to provide data for current and future stakeholder needs, CLIMAS researchers are developing spatially distributed snow water equivalent products that can give estimates of future runoff almost as quickly as snow cover conditions change. The researchers are also developing snow-covered area products using remotely sensed data such as aerial photographs and satellite images taken at different wavelengths. By applying a statistical model to the snow water equivalent point measurements from SNOTEL sites, they can obtain spatially distributed snow water equivalent estimates for the region. After correcting the results by "masking," or removing from the analysis, areas identified by remote sensing as having no snow, researchers incorporate the estimates of snow water equivalent into hydrologic models to demonstrate the use of the products to stakeholders. The overall modeling scheme is shown in Figure 2.

Figure 2. Researchers use a variety of inputs to build hydrologic models to provide streamflow forecasts for decision makers. [more details]