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Flash Droughts

Posted on April 15, 2023 by admin1  2307

In News

  • As per a recent study, flash droughts occurred more often than conventional ‘slow’ droughts in tropical places like India, Southeast Asia, sub-Saharan Africa and the Amazon basin.

More about Study

  • Flash droughts are fast becoming the ‘new normal’ making forecasting and preparing for their impact more difficult.
  • Climate change has effectively speed up the onset of droughts.
  • Reason: when the precipitation suddenly shuts off, hot, sunny and windy conditions can cause large amounts of water to evaporate quickly(i.e., high evapotranspiration)
  • The trends varied from place to place, but, looked at globally, they show a shift toward more frequent and more rapid flash droughts. 

Flash Droughts

  • About: 
    • 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.
    • There is little known about flash droughts or ‘hidden hazards’ when compared to research available on long-term droughts.
  • Occurrence:
    • Flash droughts can occur in the monsoon season as well, primarily caused by the monsoon breaks and these can also occur due to delayed onset of the summer.
  • Duration:
    • Normally, developing drought conditions take months, but flash droughts could occur in weeks and stay on for months.
  • Factors:
    • Atmospheric anomalies (variations), anthropogenic greenhouse gas emissions and ongoing climate change.
  • Detection:
    • Early-warning systems (EWS), that could identify trends in climate and sources of water, are used to detect the emergence or probability of the occurrence of flash droughts.
    • Drought monitoring through use of remote sensing data and various indices for drought monitoring as well as through on-line help facilities.

Drought

  • A drought is a period of unusually persistent dry weather that persists long enough to cause serious problems such as crop damage and/or water supply shortages. The severity of the drought depends upon the degree of moisture deficiency, the duration, and the size of the affected area.

Classification

  • Meteorological Drought: It is 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: It is 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 is identified with soil moisture deficiency in relation to meteorological droughts and climatic factors and their impacts on agricultural production and economic profitability.
  • Ecological drought: When the productivity of the natural ecosystem diminishes due to water shortage which causes ecological distress and ecosystem damage.

 Drought Prone Areas

  • In India, around 68% of the country is prone to drought to varying degrees.
  • The 35% area which receives rainfall between 750 mm and 1125 mm is considered drought prone while 33% receiving less than 750 mm is chronically drought prone.

Drought Prone Areas in India - QS Study

Map of drought prone districts of India

Major Causes

  • Variability in rainfall
  • Deviation in the route of monsoon winds
  • Early withdrawal of the monsoon
  • Forest fires
  • Frequently occurring El NINO events
  • Land degradation in addition to Climate change

Drought Management in India

  • Drought Mitigation Programs 
  • Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)
  • National Rainfed Area Programme- objective of the programme is to increase agricultural productivity in rainfed areas in a sustainable manner by adopting an appropriate farming system
  • Water Harvesting and Conservation-Farm Ponds, Percolation Tanks (PT) / Spreading Basin, Some traditional water harvesting methods like Tankas / Kunds / Kundis In the desert and arid areas of Rajasthan.
  • Rainwater Harvesting in Urban Areas 
  • Afforestation -National Green Mission is an important program to improve afforestation along with the creation of green corridors.
  • Monitoring and Early warning systems at Central and State level to declare ‘Drought’
  • Drought relief and response measures are initiated following the declaration of drought.
 
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