Sequence-Average and Cumulative Flow Loss Analyses for Colorado River Streamflow at Lees Ferry

This dataset holds scripts for Sequence-Average and Cumulative Flow Loss analyses developed to examine the severity of sustained droughts that have impact on storage and water supply in the Colorado River Basin. These analyses were performed using the methods described in Center for Colorado River Studies Future of the Colorado River Project white paper 4 entitled “The Future Hydrology of the Colorado River Basin” by Salehabadi, Tarboton et al. (2020). This study analyzed the US Bureau of Reclamation Natural flow and Tree Ring Reconstructed flow from Meko et.al., 2017, both at Lees Ferry, using the Sequence-Average and Cumulative Flow Loss plots, which show the mean flow and cumulative magnitude of departure from average conditions, or “flow loss”, for different durations. These plots presented by Salehabadi, Tarboton et al. (2020) characterize the severity of past droughts that have occurred in the Colorado River Basin. Based on examination of these plots, this study defined three drought scenarios: (1) Millennium Drought, (2) Mid-20th Century Drought, and (3) Paleo Tree Ring Severe Drought. The first two were defined using the US Bureau of Reclamation Natural flows from 2000-2018 and 1953-1977 respectively. The last was defined using the years 1576-1600 from the Meko et al., 2017 tree ring reconstruction of streamflow at Lees Ferry.