Yosemite Water Resources – NASA DEVELOP Summer 2013 @ Ames Research Center

Yosemite Water Resources – NASA DEVELOP Summer 2013 @ Ames Research Center

Articles, Blog , , 0 Comments


>>EVAN: Nestled within California’s illustrious
Sierra Nevada Mountain Range, Yosemite National Park is a vital ecosystem home to thousands of floral
and faunal species. Its majestic granite landscape and cascading waterfalls invite nearly 4 million
visitors per year, making it the third most-visited national park in the country. However, just like the
entire state of California, Yosemite has water issues. The park itself plays an instrumental role in
water availability for more than 2.4 million San Francisco Bay Area residents, yet as a society, we must
question whether this increasingly limited supply will sustain our civilization years into the future.>>CARLOS: A team at the NASA Ames Research Center in
Mountain View, CA is working with Yosemite Park hydrologist Jim Roche to develop a predictive
hydrological model for the region. The team will work directly with NASA research scientist John
Shupe to couple the Carnegie Ames Stanford Approach ecological forecasting model with HYDRA, a
hydrological routing algorithm.>>MARK: Our study area is within the state
of California, roughly 200 miles East of San Francisco. This area encompasses the entirety of Yosemite
National Park and is made up of the Upper Merced River Basin and the Upper Tuolumne River Basin.
The Upper Tuolumne contains Lake Eleanor and Hetch Hetchy Reservoir which provide power and a
majority of the water for the San Francisco Bay Area. The Tuolumne River flows into the south east
end of Hetch Hethcy and it is here that the first of our validation stream gages can be found. Further
along, south and east into the mountains we break from the Tuolumne to find the Merced River. West
along the Merced the second validation stream gage is located at the Happy Isles Bridge. Further
down the river the final validation stream gage is found at Pohono Bridge.>>JIM ROCHE: Of particular concern this year,
2013, and last year 2012, are actually low-flow conditions and understanding when that’s going to occur
and for how long because we have a number of systems in the park that are dependent on surface
water for holding water supplies. So having a product relatively off the shelf such as CASA-HYDRA
I think is a great start towards starting to help answer those questions of quantity and duration of surface
water resources.>>TEJAS: The Carnegie Ames Stanford Approach
(known as CASA) is an ecological forecasting model that takes in the total Monthly Precipitation,
as well as Minimum, Maximum and Mean monthly temperatures obtained from the PRISM climate
model. Additionally, CASA incorporates Soil Datasets, such as percent clay and Depth to Bedrock,
which are both derived from STATSGO2. As the final CASA input, Landcover data are collected from the
2006 National Landcover Dataset. All of these inputs are combined in the CASA model, which outputs
drainage, as well as the potential evapotranspiration. These CASA Outputs are combined with a Digital
Elevation Model of Yosemite National Park, and the flow accumulation and direction in the HYDRA
Model. HYDRA is a hydrological routing algorithm that incorporates easch of these inputs to produce monthly runoff values.>>AIMEE: The results are in! And our model
is currently underestimating the total flow for the entire study period by only 15%. These results were validated
by using 2 stream gages on the Merced River. Further hydrograph analysis illustrates the rate of snow accumulation and snowmelt as well as the peak magnitude
reflecting consistent trends with the observed gage values. During both high and low flow years, the model
is not producing snowpack early enough in the season and then melts it away too late in the summer.>>CARLOS: Accurately predicting the timing of
the peak runoff is absolutely crucial for water management especially during periods
of low streamflow. The coupled CASA-HYDRA model will enable Yosemite managers to better
predict seasonal runoff for improved water management. Thank you very much for listening.

Leave a Reply

Your email address will not be published. Required fields are marked *