6.7 Spatial and temporal extents of drought in the U.S

Wednesday, 22 June 2005: 3:30 PM
North & Center Ballroom (Hilton DeSoto)
Ryan S. Kangas, DRI, Reno, NV; and T. J. Brown

This study examines the spatial and temporal aspects of drought throughout the contiguous US in order to obtain a greater understanding of drought regimes including, intensity, duration, and spatial coverage. PRISM (Parameter-elevation Regression on Independent Slopes Model) is an analytical model using point data and a digital elevation model (DEM) to estimate monthly precipitation at a 4km resolution for the contiguous US back to 1895. Two datasets are constructed from PRISM data for analysis. First, the Standardized Precipitation Index (SPI) is calculated using the PRISM precipitation data for 1, 3, 6, 12, 24, 36, 48, 60, 72, 84, 96, 108, and 120-month time scales. Spatial and temporal patterns of drought are determined for these SPI time scales from 1895 to 2003. Second, the Palmer Drought Severity Index (PDSI) is calculated monthly for the 1895-2003 period. The results of both methods quantify the occurrence and frequency of drought events observed for spatial scales ranging from larger than hundreds of thousands of sq. km and covering multiple states to smaller than a few hundred sq. km. This presentation will provide results of intensity, duration and spatial extent of drought utilizing SPI and PDSI indices from PRISM data. While this project is being done in the context of fire and fuels management, the results also have value for water management, agriculture, recreation and other environmental and human interests related to water availability.
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