Context: According to a study, Mawsynram(Meghalaya) become the wettest place in the World. It has replaced Cherrapunji(Meghalaya) from the top spot. Mawsynram receives over 10,000 MM of rain in a year.

About the study

• The study looked at the rainfall pattern of the past 119 years (period of 1901–2019).It found a decreasing rainfall trend at Cherrapunji and nearby areas.
• The 1973–2019 period shows a decrease of about 0.42 mm per decade in rainfall. This trend was statistically significant at seven stations (Agartala, Cherrapunji, Guwahati, Kailashahar, Pasighat, Shillong and Silchar).

What was the need for this study?

• Northeast India is highly sensitive to changes in regional and global climate. The first signs of the effect of climate change will be evident in extreme cases such as the rainfall at Cherrapunji.
• Northeast India also has the highest vegetation cover in India. It includes 18 biodiversity hotspots of the world,
• Thus, it is important in terms of its greenery and climate-change sensitivity.

Reasons for decreasing trend of rainfall

• Changes in Temperature: The changes in the Indian Ocean temperature have a huge effect on the rainfall in the NorthEast region.
• Reduction in Vegetation Area: Satellite data analysis shows a reduction in the vegetation area in northeast India. Lesser vegetation results in changing rainfall patterns.
• Increase in Cropland Area and Deforestation: Jhum cultivation or shifting cultivation in the region has contributed to deforestation and increase in crop land area.

Jhum Cultivation

• Jhum Cultivation also known as shifting cultivation. It is a slash-and-burn agricultural practice that is widely practiced among the indigenous communities of Northeast India.
• Under this cultivation, the farmers grow the crops by first clearing the land of trees and vegetation and burning them thereafter. The burnt soil contains potash which increases the nutrient content of the soil.

Reason for High Rainfall in Cherrapunji and Mawsynram

• Cherrapunji (elevation 1313 m) and Mawsynram (elevation 1401.5 m) are located on the southern slopes of the east Khasi Hills in Meghalaya.
• Meghalaya is a mountainous state with numerous valleys and highland plateaus.
• Elevation in the plateau region ranges between 150 m to 1,961 m , with the central part comprising the Khasi Hills with the highest elevations.
• The rainfall in Cherrapunji-Mawsynram is caused by the orography favouring a monsoon wind regime.
• The northward moving moist winds from the Bay of Bengal passing over the plains of Bangladesh are forced to converge in the narrow valleys of the Khasi Hills with orography providing forced ascent that causes condensation, formation of clouds resulting in rain on the windward side of the slope.