Reviewed by Alex SmithJun 10 2022
In today’s scenario, the drought affecting the upper Colorado River Basin is especially critical. A new study was performed by the federal government and university scientists under the guidance of the Bureau of Reclamation.
The Colorado River below Glen Canyon Dam before arriving at Lees Ferry. A new study has found that the Colorado River experienced a severe drought impacting the Upper Colorado River Basin in the second century. Image Credit: Reclamation/Alex Stephens.
The study has been reported in the journal Geophysical Research Letters.
The research identified a second-century drought that is more severe than the current drought or previous droughts.
Previous studies have been limited to the past 1,200 years, but a limited number of paleo records of moisture variability date back 2,000 years. While there has been research showing extended dry periods in the southwest back to the eighth century, this reconstruction of the Colorado River extends nearly 800 years further into the past.
Subhrendu Gangopadhyay, Study Lead Author and Principal Engineer, Water Resources Engineering and Management Group, Bureau of Reclamation
The study determines that in comparison with the present 22-year drought in the Colorado River, with just 84% of the average water flow, the water flow at the time of a 22-year period in the second century was significantly lower. This is just 68% of the average water flow.
Tree-ring records are sparse back to the second century. However, this extreme drought event is also documented in paleoclimatic data from lakes, bogs, and caves.
Connie Woodhouse, Study Co-Author and Professor, University of Arizona
The authors rebuilt the streamflow at Lees Ferry on the Colorado River to develop these outcomes. Paleoclimatic data gathered for the reconstruction is from a barred network of tree-ring-based Palmer Drought Severity Index values.
Such prolonged records notify water managers if droughts in the past were similar to or more serious compared to droughts in the past. The basis for the study’s analysis utilizes the natural flow evaluation data from 1906 to 2021 from the Lees Ferry gage.
What’s Next?
The rebuilt streamflow data that was developed in this study is currently available for public use. It is anticipated that water managers will utilize this new prolonged data to comprehend past droughts better and to prepare for future droughts.
The results of this work can provide water managers with an increased understanding of the range of flow variability in the Colorado River. It should provide information to help water managers plan for even more persistent and severe droughts than previously considered.
Subhrendu Gangopadhyay, Study Lead Author and Principal Engineer, Water Resources Engineering and Management Group, Bureau of Reclamation
Woodhouse added, “For future work, collection and analysis of more remnant wood can further document this second-century drought.”
The Colorado River basin is facing a severe 22-year drought with wide impacts across the West. This water is used to supply homes and crops, as well as for the production of electricity. Drought affects everything inside the basin.
The study co-authors include Greg McCabe of the Cody Routson from Northern Arizona University, U.S. Geological Survey, and Dave Meko of the University of Arizona.
Journal Reference:
Gangopadhyay, S., et al. (2022) Tree Rings Reveal Unmatched 2nd Century Drought in the Colorado River Basin. Geophysical Research Letters. doi.org/10.1029/2022GL098781.