growth, yield will be reduced. However, droughts have different impacts on different crops.
module 2
Because of the complexity of the relationships of crop growth and water requirement, agricultural
drought is difficult to measure.
Seasonal droughts are related to deficit soil moisture during certain periods within a season.
In Bangladesh, three types of droughts are recognized during monsoon season:
■ early-season ■ mid-season ■ terminal-season
Early-season droughts are due to delayed onset or early breaks in monsoon rainfall. Mid-season
droughts are caused by intermittent, short or extended dry spells. Terminal-season droughts are
caused by early withdrawal of monsoon rainfall. In the Barind tracts of Bangladesh, terminal
droughts are more frequent and coincide with the most important growth phases of the rice
crop. Fig.2.3 shows monthly rainfall distribution in Northwestern Bangladesh and gives an idea
of different types of drought: mid-season drought (2001), terminal drought (2002) and normal
monsoon (2003).
Impact of drought
Bangladesh is affected by major country-wide droughts every five years. However, local droughts
occur frequently and affect crop life cycles. The agricultural drought, related to soil moisture
deficiency, occurs at various stages of crop growth. Monsoon failure often brings yield reduction
and famine to the affected regions. A better understanding of the monsoon cycle is clearly of
major scientific and social value.