Heat waves and droughts occured much more frequently over the past three years in India, says study

There has been a substantial increase in the frequency of concurrent meteorological droughts and heat waves across whole India

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Frequency of heatwaves and drought affecting the area
Frequency of heatwaves and drought affecting the area

Researchers from Indian Institute of Science (IISc) have found that frequency of heat waves accompanied by drought has increased in magnitude and in area over the past three decades in India.

Heat waves (a prolonged period when temperatures approach record extremes) and droughts are destructive even when occurring in separate events, their concurrence is far more serious. Single extreme event may not be critical, but two extremes occurring at once is much more significant in the distress it causes. Both phenomena have a serious bearing on water resources, affecting agriculture and human settlements.

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Highlights of the story:

  • It was found that percentage increase in frequency of heat waves along with drought were most significant in parts of Maharashtra and Southern Gujarat, Karnataka and Andhra Pradesh which may be due to intricate relationship of land surface processes, soil moisture, transpiration and local climate
  • Researchers of the study calculated the Heat wave Magnitude Index daily (HWMId) which combines duration and magnitude of heat waves, and the Standardized Precipitation Index (SPI), which defines meteorological drought from 1951 to 1981. Using that as the base, they compared it with the HWMId and SPI between the years 1981 and 2010
  • The conclusion was based on analysis of rainfall and temperature data of 50 years
  • The area affected has gone from almost nothing in 1951, to nearly 4 per cent by 2010. Nearly 18 per cent of country's area on average has been facing at least three days of temperatures above 85th percentile
  • The next step would be to factor in soil moisture along with the data to develop models that could predict where the extreme events could occur

Impact of drought in India:

  • Physical Impact : Affects the recharge of soil moisture, surface runoff and ground water table. Soils dry up, surface runoff is reduced and ground water level is lowered
  • Impact on Agriculture: Indian agriculture still largely depends upon monsoon rainfall where about two-thirds of the arable land lack irrigation facilities and is termed as rain fed. Severe shortage of food-grains had been felt and the country had to resort to import of food-grains to save the poor people from hunger and starvation. Employment levels in agricultural sector falls as well
  • Ill health and spread of diseases like diarrhea, dysentery, cholera and opthalmia caused by malnutrition, hunger and starvation
  • Migration of people from drought hit areas to other areas in search of livelihood and food
  • Rise in inflation rate and fall in purchasing power

The greatest impact of droughts are seen on the weaker sections of society. These include landless laborers, small marginal farmers and artisans like weavers. Such people live in hand to mouth economy and do not have enough stock to sustain in the event of a drought.

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