1. Drought in
Oregon
George H. Taylor
October, 2007

6. Detroit Lake, 2001

10. Definitions of Drought
An absolute drought is a period of at least 15 consecutive days to none of which is credited 0.01 inches of rain or more.
A partial drought is a period of at least 29 consecutive days, the mean daily rainfall of which does not exceed 0.01 inches.
A dry spell is a period of at least 15 consecutive days to none of which is credited 0.04 inches or more.

11. “Absolute drought”

13. Drought Indices Drought Indices Palmer Drought Severity Index (PDSI)
Surface Water Supply Index (SWSI)
Keetch-Byram Drought Index (KBDI)
Standardized Precipitation Index ("SPI")
Percent of Normal
Crop Moisture Index
Percentiles
Deciles
…others

14. Surface Water Supply Index (SWSI)
Designed as an indicator of surface water conditions for areas which are "mountain water dependent," in which mountain snowpack is a major component.
Inputs:
Precipitation
Reservoir storage
Snowpack
Stream flow
4.0 extremely wet
0 normal
-4.0 extremely dry

16. Water Availability Committee
USDA (Sect. of Ag.)
Governor
Drought Council
Water Availability Committee
Counties
OWRD SC
ODF
NRCS
NWS
USGS

17. Soil Climate Analysis Network (SCAN)

27. The End