A LANDSCAPE-SCALE RESTORATION EXPERIMENT: THE 2014 SPRING FLOOD FLOW RELEASE TO THE COLORADO RIVER DELTA, MEXICO The Colorado River delta was once a several-million acre expanse of marsh wetlands, riparian forest, and estuarine habitat located near the river’s mouth in Northwest Mexico (Glenn et al. 2001). However, the diversion of Colorado River water for human use in the arid western U.S. and northwestern Mexico resulted in the gradual drying of the delta with a subsequent loss of over 90% of original habitat (Glenn et al. 2001). Very little water has reached the delta since the era of dam construction on the Colorado River (Nagler et al. 2005), and the highly altered hydrologic regime and influx of invasive species have led to [...]
Summary
A LANDSCAPE-SCALE RESTORATION EXPERIMENT: THE 2014 SPRING FLOOD FLOW RELEASE TO THE COLORADO RIVER DELTA, MEXICO
The Colorado River delta was once a several-million acre expanse of marsh wetlands, riparian forest, and estuarine habitat located near the river’s mouth in Northwest Mexico (Glenn et al. 2001). However, the diversion of Colorado River water for human use in the arid western U.S. and northwestern Mexico resulted in the gradual drying of the delta with a subsequent loss of over 90% of original habitat (Glenn et al. 2001). Very little water has reached the delta since the era of dam construction on the Colorado River (Nagler et al. 2005), and the highly altered hydrologic regime and influx of invasive species have led to the reduction of native plant and animal populations in the delta (Glenn et al. 2001). However, modest flood flow releases to the Colorado River in Mexico have the potential to revive native vegetation along the riparian corridor (Zamora et al. 2001; Glenn et al. 2001).
An experimental pulse flow of water was delivered to the Colorado River delta in the spring of 2014. This engineered spring flood of approximately 130 million cubic meters (105,000 acre-feet) was implemented as part of the U.S.-Mexico binational agreement, Minute 319, an addition to the 1944 U.S.-Mexico Water Treaty. The term of Minute 319 is from 2012-2017, which allows for a 5-year pilot program to implement and monitor the impacts of the pulse flow release. The purpose of the pulse flow is to improve hydrologic and ecosystem conditions in the riparian corridor of the delta in Mexico to support native wildlife, particularly avian species. Although small compared to the spring floods before the construction of upstream dams and reservoirs, the pulse flow is the first transboundary water allocation for the environment.
Teams of scientists from government agencies, universities, and environmental NGOs from both the U.S. and Mexico are measuring the surface flow rates, inundation, ground water recharge, ground water levels and subsurface flows, geomorphic change, recruitment and survival of vegetation, and avian response to the pulse flow release. Monitoring includes on-the-ground observations and measurements, remote sensing, and modelling for both active and passive restoration sites. The results of this experiment may foster efforts to extend the treaty agreement for a longer-term dedication of environmental flows to the delta and may guide future efforts to effectively and efficiently manage water for the environment through pulse flow releases. No results are available at the time of writing of this abstract.
