2014 #ColoradoRiver Delta pulse flow analysis

Martha Gomez-Sapiens, a monitoring team member and postdoctoral research associate in the UA Department of Geosciences, stands on a riverbank next to willows and cottonwoods that germinated as a result of the pulse flow. (Photo: Karl W. Flessa/UA Department of Geosciences)

From KUNC (Luke Runyon):

A group of scientists, including those from the U.S. Geological Survey, are also gaining insight into how the flow was felt by plants, animals and the overall delta ecosystem.

Using a mix of groundwater monitoring and satellite imagery, scientists say even the pulse’s modest flow of water — approximately one-twentieth the amount that spilled into the delta before humans built the river’s massive upstream dams — recharged aquifers, greened plant life and spurred the return of bird species.

Years before the flow, Mexico and the United States agreed to the experiment, and to the idea that the water was not just for human use, but can and should be used to revive ecosystems. The agreement — an update to a 1944 treaty between the two countries — gave Mexico the ability to store more water in American reservoirs and, just once, flood the final miles of the dry river bed to see what happened.

From above you can use the naked eye to see the water’s effect. Before and after photos show plant life greening not just in the river’s bed where water actually flowed, but beyond the banks, which Leenhouts says is a sign of recharged groundwater.

“In the two years following the flow it was possible to measure increased green up,” using satellite images, he says.

During that same period both the number of and varied species of birds increased, he says, a side effect of the revived vegetation.

Even though the pulse flow only lasted a few months in 2014, its effects lasted for years. The greenness of vegetation wasn’t as vibrant the following year, but it was still greener compared to 2013. That indicates the single sustained flow provided enough water to keep plants alive for at least a year…

Scientists’ chance to study and test the effect of simulated floods isn’t over. A new update to the 1944 treaty signed this year allows for more pulse flows when Mexico stores surplus water.

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