NASA Ames Scientists Train the Next Generation of Earth Explorers
South of the San Francisco Bay is a 100-year tidal floodplain near NASA Ames Research Center, Moffett Field, Calif. Because of the potential for flooding, Ames purchased a segment of the mud flats for flood storm management, and has used the area for field experiments to teach and train gifted science students about the practical benefits of studying the tidal salt marsh and its wildlife.
For the last eight years, NASA Ames Earth Science Division has been participating in a student internship program called DEVELOP. Funding comes through the Applied Sciences Program in the Earth Science Division in the Science Mission Directorate at NASA Head Quarters. It is a training and development program that provides an opportunity for talented science students to learn and use sophisticated NASA technology, while mentored by science advisors from NASA and partner agencies. At the completion of the program, students share their research results with local communities, demonstrating how NASA science measurements and predictions can be used to address local policy issues.
“Every summer is full of surprises. Our students usually work on some aspect of the South Bay Salt Ponds Restoration Project,” said Jay Skiles, a research scientist and program science mentor at NASA Ames. “This year, one of our student teams studied the sedimentation now taking place in the salt ponds after some of the levees were purposely breached. The DEVELOP program is a great way for students to learn science skills and meet professionals in the field.”
During the past two centuries, the San Francisco Bay has lost an estimated 85 percent of its historic wetlands to fill or alteration. This dramatic decline in the wetlands has caused a severe impact to tidal marsh habitats and the fish and wildlife. In addition, the changed environment has increased the risk of local floods, according to South Bay Salt Ponds Restoration Project literature.
To help restore the wetlands, one of the first defenses was to build levees that separate the ponds from the tides. It was expected that once the levees breach, the sediment from the ponds would evolve into tidal marsh. In addition, by phasing the restoration of tidal marsh over many years, the need for large volumes of sediment also would be reduced.
NASA scientists regularly mentor and teach students about the scientific method, using inquiry and data collecting as a means of assessment and resolution. At Ames, scientists have taken a proactive role monitoring and studying fluvial (stream) and coastal flood sources. In this case, they helped a team of students, ranging from high school to university graduates, model the sediment deposits to predict marsh habitat development.
“I heard about the internship program while I was attending San Francisco State University,” said Michelle Newcomer, a master’s student at SFSU and a DEVELOP team member. “I applied because it sounded really exciting. I wanted to apply my geographic information system (GIS) and remote sensing skills to a real-world project.”
The five-member team called themselves the Salt Pond Restoration Sedimentation Team. They identified four project objectives: (1) track sediment transport pathways to determine the source of sediment in the South Bay; (2) calibrate satellite imagery with the collected suspended sediment concentration measurements, using Landsat 5 imagery, and data and imagery from NASA satellite instruments Moderate Resolution Imaging Spectroradiometer (MODIS), and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER); (3) create a GIS model to predict sediment deposition and (4) assess the applicability of remote sensing for predicting sediment deposition during restoration.
“We focused on two salt ponds in the Alviso complex, one of which was referred to as Pond A21. Coyote Creek is the waterway that connects the pond to the Bay. We also were interested in Pond A6 because it is the next pond to be breached; we wanted to use our model to forecast marsh accumulation in A6,” said Newcomer.
To predict marsh accumulation, students used the marsh sedimentation model, called MarSed, which was implemented in a geographic information systems platform. The conceptual model has different variables that effect marsh accumulation, including the concentration of suspended sediments, how quickly sediment settles, and time of flooding. Field work was necessary to get the suspended sedimentation measurements.
Field work consisted of going out into the San Francisco Bay on pontoon boats, provided by NASA’s Disaster Assistance and Rescue Team (DART) facility. While on the boats, students collected water samples at the bay’s surface, and recorded their exact location using a Global Positioning System (GPS) device.
Once samples were collected, students began processing them at the U.S. Geological Survey laboratory in Menlo Park, Calif.
The team concluded that (1) the delta and Coyote Creek are primary sources of suspended sediment to the Alviso ponds, (2) suspended sediment concentrations could successfully be detected using remote sensing, (3) sediment deposition for Pond A21 was successfully predicted using remote sensing and GIS techniques, and (4) Pond A6 is predicted to reach equilibrium conditions stable enough for vegetation colonization after 60 months of tidal inundation.
The team reported that restoration managers can use these products as a tool for determining the locations of pond breaches, as well as understanding the time frame of future marsh development.
“We knew that we wanted our calibrated model to do well. At the end of the project, we were all very happy, and felt accomplished that we had actually got it to work,” said Newcomer.
For more information about the DEVELOP program, visit:
For more information about the South Bay Salt Pond Restoration Project, visit:
Ruth Dasso Marlaire
Ames Research Center, Moffett Field, Calif.