Texas Forest Service Interactive Keech-Byram Drought Index Viewer

Use this view to find your county’s current KBDI

Is an index used in determining forest fire potential - John L. Keetch and George Bryam designed the drought index specifically for fire potential assessment. It is a continuous index, relating to the flammability of organic material in the ground. The drought index is based on a daily water balance, where a drought factor is balanced with precipitation and soil moisture (assumed to have a maximum storage capacity of 8-inches) and is expressed in hundredths of an inch of soil moisture depletion.

The drought index ranges from 0 to 800, where a drought index of 0 represents no moisture depletion, and an index of 800 represents absolutely dry conditions. Presently, this index is derived from ground based estimates of temperature and precipitation derived from weather stations and interpolated manually by experts at the Texas Forest Service (TFS) for counties across the state.

At any point along the scale, the index number indicates the amount of net rainfall that is required to reduce the index to zero, or saturation. The inputs for KBDI are weather station latitude, mean annual precipitation, maximum dry bulb temperature, and the last 24 hours of rainfall. Reduction in drought occurs only when rainfall exceeds 0.20 inches (called net rainfall).

KBDI levels and its relationship to expected fire potential are reflected in the following table:

KBDI = 0 – 200: Soil moisture and large class fuel moistures are high and do not contribute much to fire intensity.
KBDI = 200 – 400: Lower litter and duff layers are drying and beginning to contribute to fire intensity.
KBDI = 400 – 600: Lower litter and duff layers contribute to fire intensity and will burn actively.
KBDI = 600 – 800: Often associated with more severe drought with increased wildfire occurrence. Intense, deep-burning fires with significant downwind spotting can be expected. Live fuels can also be expected to burn actively at these levels.