Colorado river delta reborn

AGUA! Agua!” shouted the crowd as the water gushed past towards the parched Colorado river delta. On 23 March, as part of an agreement between the US and Mexican governments, a giant pulse of water was released through the Morelos dam on the US-Mexico border. Over the next eight weeks, 130 billion litres will pour through the dam to rejuvenate the delta, followed by a lower flow for the next three years. It is the first time that water has ever been released into Mexico for environmental purposes. The delta needs it: the river hasn’t flowed to the sea regularly since the 1960s, when the dam was built. A huge team of scientists will PETE MCBRIDE/NATIONAL GEOGRAPHIC/GETTY–Morelos dam before the releasemonitor the outcome, watching eagerly as the delta springs back to life. Data coming from sensors placed in the riverbed will measure soil and water properties like temperature, salinity and how fast groundwater recharges. The team will also be watching to see if the region’s once-teeming bird populations flock back to the stretches of open water. Meanwhile, remote monitoring from sensors on planes, helicopters and satellites will track vegetation growth and tiny changes in elevation as the ground settles under the weight of the water. “You can’t get a handle on a project this big without taking measurements from the air,” says team leader Karl Flessa at the University of Arizona in Tucson.