Flash Droughts

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    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.