FLASH DROUGHTS

Subject: Geography

Context: A new study has now pointed out that India could experience more such flash droughts by the end of this century.

Several factors including atmospheric anomalies, anthropogenic greenhouse gas emissions play an important role.

Concept:

Fash drought is the rapid onset of drought.
It can develop in as little time as 10 to 15 days.
In contrast with conventional drought, which is mainly driven by lack of precipitation, flash drought usually includes abnormally high temperatures, winds, and/or incoming radiation that leads to abnormally high evapotranspiration (ET) rates.
Flash droughts occur more often than perceived and can cause major agricultural losses if they are not predicted and detected in a timely manner.
The prediction of flash droughts on subseasonal timescales is of critical importance for impact assessment, disaster mitigation, and loss prevention.

Findings of the study

The research team found that flash droughts had sudden decreases in ET anomaly over the drought regions before onset.
That means that soil moisture was plentiful prior to the drought, but rapidly evaporated due to heat/wind/radiation.
The researchers noticed sharp declines in soil moisture anomaly associated with the sudden decreases in ET anomaly.
Temperatures during the development periods were warmer than normal, due to heatwaves in the regions, and the three-month Standardized Precipitation Indexes were negative for flash droughts.
This suggests that closely monitoring rapid changes in ET (a responding variable to temperature), along with soil moisture and precipitation conditions, can provide early warnings of flash drought development.