Modeling Yosemite’s Water Budget: It’s HYDRA-Logical!

Map of Yosemite National PArk. Image Credit: DEVELOP

Image Credit: DEVELOP

Authors: Evan Johnson, Andrew Nguyen, Vanessa Archambault, Jeffrey Stine

Mentors/Advisers (affiliation): John Shupe (NASA Ames Research Center) Jim Roche (National Park Service), Cindy Schmidt (Bay Area Environmental Research Institute)

Team Location: Ames Research Center, Moffett Field, California

Abstract: Historic trends reveal extreme precipitation variability within the Yosemite National Park (YNP) geographic region. California obtains greater than half of its annual water supply from the Sierra Nevada snowpack. However, precipitation and runoff can fluctuate between less than 50 percent and greater than 200 percent of climatological averages. Such unpredictability presents a constant challenge for water managers throughout the state. Advances in hydrological modeling are crucial to improving water-use efficiency at the local, state, and national levels. The NASA Carnegie Ames Stanford Approach (CASA) is a global simulation model that combines multi-year satellite, climate, and other land-surface databases to estimate biosphere-atmosphere exchange of energy, water, and trace gases from plants and soils. By coupling CASA with a hydrologic routing algorithm known as Hydra, it is possible to calculate current water availability and observe hydrological trends within YNP. The inclusion of satellite-derived inputs such as surface evapotranspiration, temperature, precipitation, land cover, and elevation enabled the creation of a valuable decision-support tool for YNP’s water resource managers. This geospatial assessment generated a standardized method which may be repeated in both national and international water-stressed regions.