DECREASING TREND IN RAINFALL
23/02/2021

Tags:

CONTEXT:
  • It has been found in the recent study that looked at the rainfall pattern in the past 119 years found a decreasing trend at Cherrapunji (Meghalaya) and nearby areas.
ABOUT:
  • The village of Mawsynram in East Khasi Hills district of Meghalaya has beaten Cherrapunji to become the wettest place in the world.
  • Mawsynram receives over 10,000 millimetres of rain in a year. It is located around 81 km by road from Cherrapunji however the straight line distance between the two is 15.2 km.
FINDINGS:
  • The annual mean rainfall for the period 1973–2019 showed decreasing trends of about 0.42 mm per decade.
  • It was statistically significant along seven stations like Agartala, Cherrapunji, Guwahati, Kailashahar, Pasighat, Shillong and Silchar.
  • The phenomenon is driven by changes in the Indian Ocean temperature and conversion of forestlands and vegetation cover to croplands in the last two decades.
  • These long-term rainfall changes in the region are responsible for the observed shift of the world’s wettest place from Cherrapunji to Mawsynram (separated by 15-km) in recent decades.
  • Mawsynram receives an average annual rainfall of 11,871 mm while Cherrapunji braces for torrential rains every year with an annual average at 11,430 mm.
  • Largest rainfall areas are also showing changes in rainfall and that is important for water management.
  • Since North East India is mostly hilly and is an extension of the Indo-Gangetic Plains, the region is highly sensitive to changes in regional and global climate. Pre-monsoon and monsoon are the rainy seasons of North East India.
                                                        
CAUSES:

  • Around 80 percent of India’s annual rainfall comes from the Indian summer monsoon, spanning from June to September.
  • But deforestation over the past few decades has caused summer monsoon to weaken, resulting in a considerable decline in rainfall.
  • Large-scale conversion of forests to crop lands is disrupting India’s rainfall.
  • Reduction in the vegetation area in northeast India in the past two decades, implying that human influence also plays an important role in the changing rainfall patterns.
  • Jhum cultivation or shifting cultivation is now decreased and being replaced by other methods.
CONCLUSION:
  • Hence a reliable estimate of the trend and/or multi-decadal variability of mean rainfall over the North East India and that of the extreme events are critical for delineating the impact of climate change over the region.
  • A better understanding of the physical mechanisms of the North East India’s rainfall variability is crucial for developing advanced projections of future rainfall variability.
Quiz of the Day for IAS Prepation
Test Your UPSC Preparation With Vajirao's Daily Current Affairs Quiz

Select the correct answer and click on the “Finish” button Check your score and explanations at the end of the quiz

Start Quiz