Monsoon is normally associated with flash floods. But a team of Indian researchers found that a kind of rapidly developing drought also manifests during the prominent rainy season.
- What are Flash Droughts?
- Causes of Flash Droughts
- Effects of Flash Droughts on Agriculture
- Reasons for their increase in India
- Prevention and Mitigation Measures
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.
- Drought is a deficiency in precipitation over an extended period.
- It is a normal, recurrent feature of climate that occurs in virtually all climate zones.
The prolonged period of abnormally low rainfall, leads to a shortage of water.
- Meteorological Drought: classified based on rainfall deficiency with respect to long term average, where 25% or less is normal, 26-50% is moderate and more than 50% is severe.
- Hydrological Drought: defined as deficiencies in surface and subsurface water supplies leading to a lack of water for normal and specific needs. Such conditions arise even in times of average (or above average) precipitation when increased usage of water diminishes the reserves.
- Agricultural Drought: it’s identified with soil moisture deficiency in relation to meteorological droughts and climatic factors and their impacts on agricultural production and economic profitability.
Drought Prone Areas:
- In India, around 68% of the land area is prone to drought to varying degrees.
- The 35% area which receives rainfall between 750 mm and 1125 mm is considered drought prone
- 33% receiving less than 750 mm is chronically drought prone.Meteorological Drought: classified based on rainfall deficiency with respect to long term average, where 25% or less is normal, 26-50% is moderate and more than 50% is severe.
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.
- Groundwater is the source of 40% of India’s water needs and it is depleting at an unsustainable rate
- As per NITI Aayog’s 2018 report 21 Indian cities – including Delhi, Bengaluru, Chennai and Hyderabad – are expected to run out of groundwater by 2020
- 40% of India’s population will have no access to drinking water by 2030
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.
Approach to the answer:
- Define Flash droughts
- Identify the differences between flash droughts and normal droughts
- Briefly discuss the effects of flash droughts in India
- Mention the prevention and mitigation measures