This resource is an updated version of the following resource:
Salehabadi, H., D. Tarboton (2022). Hydrology scenarios that characterize plausible future drought conditions in the Colorado River Basin, HydroShare, https://doi.org/10.4211/hs.ca2e152c9fca4b2aa7c3294a388c522d

The previous dataset was updated using the most recent version (last updated on 12/15/2022) of the US Bureau of Reclamation Natural Flow database, covering the time period from 1906 to 2020. In addition to this update, the dataset now provides CRSS-ready-to-use input files including:
• Flow inputs at 29 CRSS sites
• MWD_ICS.SacWYType (Sacramento Water Year Type)
• TMD_East_Slope_Supply.St_Vrain_Annual_Flow (St Vrain Annual Flows)
• HydrologyParameters.SupplyScenario
• HydrologyParameters.TraceNumber
• MeadFloodControlData.hydrologyIncrement

This dataset holds streamflow sequences for three drought scenarios developed to characterize plausible future drought conditions in the Colorado River Basin. These sequences were produced 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) and paper Salehabadi, H., D. G. Tarboton, B. H. Udall, K. G. Wheeler and J. C. Schmidt, (2022), "An Assessment of Potential Severe Droughts in the Colorado River Basin," JAWRA Journal of the American Water Resources Association, https://doi.org/10.1111/1752-1688.13061. The three defined drought scenarios are as follows: (1) Millennium Drought, (2) Mid 20th Century Drought, and (3) Paleo Tree Ring Drought. The first two droughts were defined using the US Bureau of Reclamation Natural flows from 2000-2020 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. 100 streamflow traces, each 50 years long were produced for each scenario by resampling years with replacement. Resampling from identified past drought scenarios, provides test droughts based on past flows that are more severe, due to the variety in the sampling, than any past droughts that have actually occurred. They are nevertheless plausible, since they are derived from past records. We used a nonparametric resampling approach referred to as “Water Year Block Disaggregation” to split the simulated annual flow at Lees Ferry into monthly flows at each of the 29 Colorado River Simulation System (CRSS) natural inflow sites. For the first two scenarios where there are historical natural flows at the 29 CRSS sites, this selects the entire water year block of monthly flows across sites for the corresponding drought year. For the paleo scenario, where there are no flows at the sites, the historical natural flow year with the annual flow at Lees Ferry closest to the paleo flow is selected and then flows across the sites and months adjusted by the ratio of paleo flow to closest historical flow.