Keetch–Byram Drought Index (KBDI)


Drought means, receiving less rainfall than what we expect. It can happen anywhere in the world. Drought indices summarized associated data like rainfall, stream flow, etc. into a single number which can be used to obtain comprehensible big picture. Some of well-known Drought indices are, Palmer’s Index (Palmer, 1965), Keetch–Byram Drought Index (Keetch and Byram 1968), Standardized Precipitation Index (McKee et al,. 1993, 1995), Vegetation Condition Index (Kogan 1998).

With development of Remote Sensing Technology, scientists were able to formulate drought indices with remote sensing data with better spatial resolution and extent. One of them is Keetch–Byram Drought Index (KBDI). Originally, KBDI was developed by John L. Keetch and George Bryam in 1968 (Keetch, John J; Byram, George, 1968, "A drought index for forest fire control"). Typically, it was applied in wild-fire potential assessment in USA. KBDI reflects water gain or loss within the soil (Simply, Evaporation is minus and Precipitation is plus) using Mean annual rainfall, daily rainfall and daily maximum temperature as input parameters. It is ranging from 0 (no drought) to 800 (extreme drought). Mathematical representation of KBDI is shown below,






GSMaP Rainfall


The amount of rainfall and its spatial distribution are important for water resources assessment, flood and drought prediction. In many developing countries the availability of ground measuring stations is very limited and unevenly distributed, making assessment of water resources and flood forecasting difficult. The availability of several high resolution global satellite based rainfall products by various operating agencies such as Global Satellite Mapping of Precipitation (GSMaP), CMORPH, TRMM Multi satellite Precipitation Analysis provides information of rainfall occurrence, amount and distribution in such data sparse region. Among them, GSMaP provides the highest resolution satellite-based products at a finer temporal scale.

Initially the project of GSMaP was promoted as a research study for producing high resolution and high precision global precipitation map using satellite data sponsored by JST (Japan Science and Technology. Since 2007, this project was promoted and initiated by Japan Aerospace Exploration Agency (JAXA) as Precipitation Measuring Mission.




 KBDI - Drought in Thailand 2011




This Image shows monthly KBDI (Left: Jan to Right: Dec) from 2007 to 2012. Offset of Wet Season in Thailand (Usually June to October) can be observed in 2010 which leads to Drought Condition in Thailand.