Flash Droughts

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What are Flash Droughts?

• Flash droughts refers to a severe drought kind of situation that develops very quickly and are characterized by rapid soil moisture depletion. 
• Normally, drought conditions take months to develop and are caused by prolonged lack of precipitation or rains.
• But Flash droughts are an extreme climate phenomena that happen within a week or in two weeks’ time and intensify very quickly.
• In India, most of the flash droughts occur during the Monsoon Season.
• Researchers from the Indian Institute of Technology, Gandhinagar  identified 39 flash droughts during 1951-2018 and found that 82 per cent of those occurred during the monsoon season.

Causes of Flash Droughts

• We know very little about flash droughts — or ‘hidden hazards’ — when compared to research available on long-term droughts.
• But, scientists agree that flash droughts are mostly driven by heat waves and very high temperatures.  
• They are usually affected by conditions that lead to abnormally high evapotranspiration (ET) rates such as abnormally high temperatures, winds, and/or incoming radiation.
• Several factors including atmospheric anomalies, anthropogenic greenhouse gas emissions play an important role.
• A considerably long dry spell with significantly low precipitation anomalies during the monsoon results in an increase in air temperature. 
• Increased air temperature and precipitation deficit together cause a rapid depletion of soil moisture leading to flash drought. 
• Therefore, flash droughts in the monsoon season are primarily caused by the monsoon breaks. However, flash droughts can also occur due to delayed onset of the summer.
• In India, prolonged dry spells during the monsoon season — are leading to a flash drought. This happens because rains stay away for 15-20 days at a stretch.

Effects of Flash Droughts on Agriculture:

• Flash droughts are mainly concentrated in the monsoon season in the majority of India. 
• They affect crop production and pose challenges in meeting increased irrigation demands
• This can adversely affect maize and rice grown in the Kharif (June-September) season.
• About 10-15 per cent areas under cultivation of rice and maize were affected by flash droughts during the monsoon seasons in India between 1951 and 2018, a recent study has found.
• In 1979, India faced a severe flash drought, affecting about 40% of the country and taking a toll on agriculture. The big granaries of Uttar Pradesh and Andhra were affected, and the country suffered a loss of about ₹5,000 crores.

Reasons for increase in Flash Droughts in India

• The ongoing climate change has caused a significant increase in global temperature and this can lead to more and more flash droughts in the coming years.
• Around the world, stronger El Niño weather patterns and the ongoing climate breakdown are bringing harsher and more frequent droughts. India is also hard hit by this.
• The changes in greenhouse gas emissions, industrial aerosols, and land-use/land-cover can disrupt the pattern of summer monsoon precipitation, sea surface temperature, and air temperature over India. 
• Scientists predict that as temperatures continue to rise with global heating and populations grow, Indian region will experience harsher water shortages. 
• A recent study by researchers from IIT Gandhinagar concluded that the frequency of concurrent hot and dry extremes is projected to rise by about five-fold. This may cause an approximately seven-fold increase in flash droughts like 1979 by the end of the 21st century
• This increased frequency of flash droughts can have deleterious implications for crop production, irrigation demands and groundwater abstraction in India.

Prevention and Mitigation Measures

• Flash droughts have severe impacts and occur when regular drought conditions rapidly intensify. 
• This makes it more urgent to accurately identify the physical processes behind their origins.
• Early-warning systems (EWS) that could identify trends in climate and sources of water were needed to detect the emergence or probability of the occurrence of flash droughts.
• EWS and drought monitoring helps in formulating an effective, proactive drought policy.
• If the ‘Paris Agreement’ goals are met and global warming is restricted to well below 2 degrees C, the numbers and frequency of the projected flash droughts may go down.