HR: 1340h
AN: H33B-1384    [Abstracts]
TI: Hydrological and Meteorological Drought Severity in Oregon: Comparisons Between the Surface Water Supply Index (SWSI) and Standardized Precipitation Index (SPI)
AU: * Keyantash, J
EM: jkeyantash@csudh.edu
AF: California State University, Dominguez Hills, Dept. of Earth Sciences 1000 E. Victoria St., Carson, CA 90747 United States
AB: The water year of 2005 brought widespread drought to the Pacific Northwest and northern Rocky Mountain states (Wyoming and Montana). These drought conditions may be quantified as shortages in precipitation (meteorological drought) and additionally as deficiencies in current and potential surface water resources (hydrological drought), such as streamflow, reservoir storage, and snowpack. Two widely-used indices designed for the quantification of meteorological and hydrological drought are the Standardized Precipitation Index (SPI) and the Surface Water Supply Index (SWSI), respectively. The commonalities and differences for these two drought indices are compared for two climate divisions in Oregon--representing moist and dry environments--for water years 1976 through 2005. Additionally, the 2005 Oregon drought is statistically described in terms of its return period. SPI values are readily translated into exceedance probabilities, but such an approach is atypical for the SWSI (viz., the SWSI is computed using nonexceedance probabilities for its input hydrological variables, but the index itself is not considered as a Gaussian variable). This paper examines the probability distributions of historical monthly SWSI values in Oregon, to ascertain whether consecutive monthly values of the SWSI may be combined to describe the 2005 drought event in terms of its exceedance probability. Such a product would mirror the abilities of the SPI, which can quantify the severities of drought intervals using the perspective of multiple timescales.
DE: 1812 Drought
DE: 1833 Hydroclimatology
DE: 1872 Time series analysis (3270, 4277, 4475)
SC: Hydrology [H]
MN: Fall Meeting 2005