Abstract:
Drought is a major natural hazard that causes the earth to parch and a considerable
hydrologic or water imbalance resulting water shortages, wells to dry, depletion of
ground water and soil moisture, stream flow reduction, crops to wither leading to
crop failure and scarcity in fodder for livestock. This study analyzed drought
diagnosis and monitoring over Bangladesh. Emphasis is given to analyze
meteorological drought through calculation of Standardized Precipitation Index (SPI).
Other popular drought indices are not utilized due to the lack of observed data.
Besides observed dataset, Regional Climate Model output is utilized in calculation of
SPI at different station locations over Bangladesh. The historical records of drought
event extracted from Bangladesh Statistical Bureau (BBS) and International Disaster
Database EM-DAT are used to confirm the drought which detected by the model
data SPI calculation for particular drought month/year. The main goal of this
research is to identify the utility of climate model outputs in projecting drought
phenomenon in this region. The SPI is calculated for month 1, month 2... month 6,
month 9, month 12, month l5, month 18, month 2l and month 24 using observed and
model datasets. In calculation of SPI, 27 station locations data over Bangladesh
during 1961 to 1990 is utilized. It is found that point information at a particular
station location is not enough to detect drought condition using model data with
reference to the observed values. Sometimes observed data also show drought in one
location but opposite situation (surplus of rainfall) in other nearby location due to the
huge variation of rainfall in place-to-place. Regional average information provides
better understanding in detection of drought compared to point information because
drought is a regional phenomena. It is not possible to detect same month/year as a
drought situation by both datasets used in this study suggests further study with more
datasets and new technique. Overall, model outputs employed SPI during 196l-1990
can detect moderate and severe drought compared to the extreme cases over
Bangladesh. Historical record of drought confirms drought detection by the model
data. This infers that statistics of drought may be helpful in preparedness from
impacts of drought in agricultural and water resources sectors even though particular
drought month/event may not be projected very accurately.
