The Keetch–Byram drought index (known as KBDI), created by John Keetch and George Byram in 1968 for the United States Department of Agriculture's Forest Service, is a measure of drought conditions. It is commonly used for the purpose of predicting the likelihood and severity of wildfire. It is calculated based on rainfall, air temperature, and other meteorological factors.[1]
The KBDI is an estimate of the soil moisture deficit, which is the amount of water necessary to bring the soil moisture to its full capacity. A high soil moisture deficit means there is little water available for evaporation or plant transpiration.[2] This occurs in conditions of extended drought, and has significant effects on fire behaviour.
In the United States, it is expressed as a range from 0 to 800, referring to hundredths of an inch of deficit in water availability; in countries that use the metric system, it is expressed from 0 to 200, referring to millimetres.[3]
| Index value (hundredths of inches) | Index value (millimetres) | Implications[3][4] |
|---|---|---|
| 0–200 | 0–50 | Soil is moist. 0 represents a completely saturated soil.[5] |
| 200–400 | 50–100 | Leaf litter begins to dry. |
| 400–600 | 100–150 | Lower litter actively contributes to fire intensity and will burn actively. |
| 600–800 | 150–200 | Associated with severe drought and extreme fire behaviour. |
See also
edit- National Fire Danger Rating System
- Palmer drought index
- Standardised Precipitation Evapotranspiration Index
- McArthur Forest Fire Danger Index
- Drought
- 1988 revision of the paper, "A drought index for forest fire control.". http://www.srs.fs.fed.us/pubs/rp/rp_se273.pdf Archived 2016-03-03 at the Wayback Machine
References
edit- ^ Keetch, John J.; Byram, George M. (1968). "A Drought Index for Forest Fire Control". Res. Pap. Se-38. Asheville, Nc: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 35 P. 038. USDA Forest Service Southern Research Station. Retrieved August 11, 2016.
(Date: 1968) Res. Paper SE-38. 32 pp. Asheville, NC: U.S. Department of Agriculture, Forest Service
- ^ Finkele, Klara; Mills, Graham A. (September 2006). "National gridded drought factors and comparison of two soil moisture deficit formulations used in prediction of Forest Fire Danger Index in Australia". Australian Meteorological Magazine. 55 (3): 183–197.
- ^ a b "Weather and Bushfire Behaviour" (PDF). NSW Rural Fire Service. Retrieved 20 March 2018.
- ^ "Keetch-Byram Drought Index".
- ^ "Real-time Drought Assessment System of Texas A&M Forest Service" (PDF). Retrieved 20 April 2022.
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