More than a decade has passed since the waters
of the Colorado have reached the Sea of Cortez.
During that time, the lower reaches of the river have seen a decline in the amount of healthy vegetation.
But a historic agreement between the U.S. and Mexico
provided a pulse of water to flow down the riverbed and into the delta region.
The lower Colorado River straddles the border between Mexico and the U.S.,
and the two countries are collaborating to study the hydrologic and ecosystem effects of the pulse flow.
For several weeks in the spring of 2014,
a pulse of water passed through the Morelos Dam
totalling 130 million cubic meters,
enough to fill 52,000 Olympic swimming pools.
The water quickly filled the formerly dry riverbed.
Much of the water soaked into the ground in the first half of the journey,
replenishing the supply of ground water. From there it is able to nourish and revitalize
the trees, shrubs, and grasses in the riparian corridor surrounding the river.
Scientists with the U.S. Geological Survey
are using data from satellite observations to track how the vegetation responds
Data from Landsat 8 shows a 40% increase in green vegetation where the surface water flowed
and an overall 23% increase throughout the riparian corridor.
The difference between 2014 and 2013 is most noticeable in the wetlands of the lower delta region.
Going forward, scientists from both countries will continue to study the impact of the pulse flow;
looking to see whether new trees and shrubs take root,
and how new vegetation affects resident and migratory birds.
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