HR: 1340h
AN: H33B-1382    [Abstracts]
TI: Identifying Oscillatory Responses on Precipitation and Persistent Drought Conditions in the Colorado River Basin
AU: * Cañón, J
EM: jecanonb@email.arizona.edu
AF: The University of Arizona, Dept. of Hydrology and Water Resources, Tucson, Az 85721 United States
AU: * Cañón, J
EM: jecanonb@email.arizona.edu
AF: Universidad de Antioquia, Departamento de Ingenieria Sanitaria y Ambiental Calle 67 N§ 53-108 Bloque 20 of.415, Medellin, s/n Colombia
AU: Gonzalez, J
EM: javier.gonzalez@uclm.es
AF: Universidad de Castilla-La Mancha, Dept. de Ingenieria Civil Avda Camilo Cela , Ciudad Real, s/n Spain
AU: Valdes, J
EM: jvaldes@u.arizona.edu
AF: The University of Arizona, Dept. of Civil Engineering and Engineering Mechanics,MS 210072, Tucson, Az 85721 United States
AB: Estimating precipitation occurrence and identifying drought conditions are two of the major tasks faced by water resources managers in the Colorado River Basin (CRB). In this study, the Standardized Precipitation Index (SPI) was chosen to analyze the spatial and temporal distribution of precipitation over the CRB at different aggregation scales (monthly, seasonal and annual). The oscillatory response of the SPI, considered as a single variable as well as in terms of its correlated response to the ENSO and PDO indices, was analyzed using Empirical Orthogonal Functions (EOF) and Multichannel Singular Spectrum Analysis (MSSA) over time series of 103 years, from 1900 to 2003. The reconstructed components of SPI showed significant oscillatory responses around 5 and 20 years that coincide with the reconstructed oscillations of the ENSO and PDO signals, respectively. The reconstructed components of SPI tend to be below normal during the cold phase of PDO and above normal during the warm phase of PDO. The oscillations were consistent within the different periods of aggregation and sub basin regions analyzed. The annual and winter aggregations show the larger dependence among the SPI, PDO, and ENSO signals. The occurrence of extreme SPI values associated with ENSO and PDO was also evaluated in terms of a common product of these indices that highlights years 1941 and 1982-1983 as extremely wet and years 1956, 1974, 1997 and 2002 as extremely dry. Periods with generalized values of SPI above normal conditions were identified in 1905-1909, 1978-1988, and 1992-2000 whereas generalized SPI values below normal conditions were found in 1901-1904, 1931-1934, 1953-1956, 1974-1977, 1989-1990 and 2000-2002. These results agree in general with those obtained applying a new Drought Frequency Index (to be presented in an accompany abstract) developed by one of the authors to determine the spatial distribution and persistency of droughts.
DE: 1812 Drought
DE: 1833 Hydroclimatology
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
SC: Hydrology [H]
MN: Fall Meeting 2005