Computer calculation of the Keetch-Byram Drought Index-programmers beware!
Document Type: Journal Article
Author(s): Martin E. Alexander
Publication Year: 1990

Cataloging Information

  • calculation errors
  • drought index
  • equations
  • KBDI - Keetch-Byram Drought Index
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Record Maintained By:
Record Last Modified: March 27, 2018
FRAMES Record Number: 10946


From the introduction: The Keetch-Byram Drought Index or KBDI has been or is still being used as a guide for estimating the cumulative moisture deficiency in deep duff or upper soil layers. Such information is needed for planning fire management operations in many regions of the world. As well, the KBDI has been widely utilized in various fire research studies. It has come to my attention (Crane 1983) again that there are two significant typographical errors in the original 1968-published USDA Forest Service Research Paper SE-38 dealing with the drought index developed by John J. Keetch and George M. Byram. Crane determined that the equation used to calculate the daily drought factor was in fact incorrect. The last constant in the numerator of Equation 18 on page 31 of Keetch and Byram's (1968) publication should have been 8.30 and not 0.083. The end result of this error is a drought factor that is always slightly higher than the correct value.

Online Link(s):
Alexander, M. E. 1990. Computer calculation of the Keetch-Byram Drought Index-programmers beware! Fire Management Notes 51(4):23-25.