Browsing by Author "Hidalgo, Hugo"

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    Five Hundred Years of Hydrological Drought in the Upper Colorado River Basin
    (2007-06) Timilsena, Janak; Piechota, Thomas C.; Hidalgo, Hugo; Tootle, Glenn; University of Alabama Tuscaloosa
    This article evaluates drought scenarios of the Upper Colorado River basin (UCRB) considering multiple drought variables for the past 500 years and positions the current drought in terms of the magnitude and frequency. Drought characteristics were developed considering water-year data of UCRB’s streamflow, and basin-wide averages of the Palmer Hydrological Drought Index (PHDI) and the Palmer Z Index. Streamflow and drought indices were reconstructed for the last 500 years using a principal component regression model based on tree-ring data. The reconstructed streamflow showed higher variability as compared with reconstructed PHDI and reconstructed Palmer Z Index. The magnitude and severity of all droughts were obtained for the last 500 years for historical and reconstructed drought variables and ranked accordingly. The frequency of the current drought was obtained by considering two different drought frequency statistical approaches and three different methods of determining the beginning and end of the drought period (annual, 5-year moving, and ten year moving average). It was concluded that the current drought is the worst in the observed record period (1923-2004), but 6th to 14th largest in terms of magnitude and 1st to 12th considering severity in the past 500 years. Similarly, the current drought has a return period ranging from 37 to 103 years based on how the drought period was determined. It was concluded that if the 10-year moving average is used for defining the drought period, the current drought appears less severe in terms of magnitude and severity in the last 500 years compared with the results using 1- and 5-year averages.
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    The Western U.S. Drought: How Bad Is It?
    (2004-08-10) Piechota, Thomas C.; Timilsena, Janak; Tootle, Glenn; Hidalgo, Hugo; University of Alabama Tuscaloosa
    Historical stream flow records and the forecast for 2004 make the current (1999–2004) drought in the southwestern United States the worst one in the past 80 years for portions of the Upper Colorado River Basin (UCRB).For the Colorado River (near Cisco, Utah), the cumulative stream flow deficit (departure from long‐term mean) for the current drought is almost 11 km8, or approximately 2 years of average stream flow Although the current drought is the most significant, based on historical stream flow records, is it the worst ever?