Bringing Life to Colorado With Experimental Flow

Just last spring, a rejuvenating pulse of river water rushed down to the lower reaches of the drying Colorado River. Now, new NASA satellite imagery is showing the stunning results of this life-granting experiment.

Unlike stronger flowing rivers, the Colorado River doesn't always feed into far shores. In fact, the year was 2000 when the river last reached the Sea of Cortez, found between Mexico's mainland and Baja California. Since then the river's lower reaches have receded, resulting in a heavy decline of healthy vegetation along river shores.

Now an experimental release of river water, as part of collaboration between the United States and Mexican governments back in March, appears to have rejuvenated life along the river, resulting in an at-least 40 percent increase in green vegetation since the decline.

"The vegetation that desperately needed water was finally able to support more green leaves," Pamela Nagler, of the US Geological Survey's (USGS) Southwest Biological Science Center, said in a recent statement. "These are existing trees, like saltcedar, willow and cottonwood, and a lot of shrubs and grasses that hadn't seen much water in a long time."

Nagler and other members of the Minute 319 Science Team used sensors on USGS/NASA's Landsat 8 satellite to track the response of plants to the pulse of water. Comparing Landsat data and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite, the team calculated a 43 percent increase in green vegetation along the route directly wetted by the flow, and a 23 percent increase in greening along the river banks.

"In addition to remote sensing, ground-based geophysical methods such as time-lapse gravity maps provide information about the change in groundwater storage, which ultimately supports riparian vegetation," added Jeff Kennedy, USGS hydrologist and participant in the study.

The apparent success of this experiment will likely mean that carefully controlled water pulses will be used to keep thirsty riverbeds healthy in the future, even while trying to conserve how much water is briefly released from nearby dams.

Using greenness data collected both from the ground and from satellites, researchers will continue to investigate the long-term impacts to groundwater and study whether or not new trees and shrubs take root following these life-granting flows.

[Credit: NASA's Goddard Space Flight Center]

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