Recently, a detailed study has been conducted on the rainfall pattern of the past 119 years in the northeastern region of India. The results reveal a significant decrease in the annual rainfall in Cherrapunji, Meghalaya, and its surrounding regions. Notably, Mawsynram village in the same state has now usurped the title of the world’s wettest place from Cherrapunji. This article will discuss these findings along with other relevant aspects.
An Overview of Rainfall Reduction
The research presents an interesting fact that the mean annual rainfall during the period of 1973-2019 witnessed a reduction about 0.42 mm per decade. This declining trend is statistically significant for seven stations, namely Agartala, Cherrapunji, Guwahati, Kailashahar, Pasighat, Shillong, and Silchar.
The Reasons Behind The Decrease
The study highlights two main causes behind this change in rainfall pattern. One is the consequence of rising temperatures, particularly in the Indian Ocean region. This region plays a vital role in determining the rainfall in the northeastern region of India. The increasing sea surface temperatures in the tropical Indian Ocean were noted by the first climate change assessment report published by the Union Ministry of Earth Sciences in 2020.
Another significant cause related to the change in rainfall is increased human activities, which have led to substantial vegetation reduction in Northeast India over the past two decades. There has been a marked decrease in Jhum or shifting cultivation, and considerable deforestation in the region. Furthermore, there has been an expansion of cropland, especially after 2006, resulting in the loss of vegetation cover of 104.5 sq km per year. Simultaneously, cropland saw a significant increase (182.1 sqkm per year), and urban areas also expanded (0.3 sq km per annum) during 2001-2018.
The Importance of Studying the Northeast Region
Being a hilly extension of the Indo-Gangetic Plains, Northeast India is highly sensitive to changes in global and regional climate. For instance, the impact of climate change is evident in extreme cases like the decreased rainfall at Cherrapunji. The region boasts the highest vegetation cover in India and houses 18 biodiversity hotspots worldwide, emphasizing its significance towards preserving greenery and mitigating climate change.
Why Are Cherrapunji and Mawsynram Notably Wet?
Cherrapunji and Mawsynram, located on the southern slopes of the east Khasi Hills in Meghalaya, are known for their high rainfall due to favorable geographical factors. The moist winds from the Bay of Bengal, which pass over Bangladesh’s plains, converge in the narrow valleys of the Khasi Hills. Here, the hilly orography forces an upward movement, causing condensation and cloud formation, resulting in heavy rainfall on the windward side of the slope.
Shifting Cultivation: A Double-edged Sword
The indigenous communities of Northeast India widely practice ‘Jhum’ or shifting cultivation. This method involves clearing land by slashing vegetation and burning forests for agricultural use. While it provides an efficient land preparation method, offering food, fodder, fuel, and livelihood to the families, it also contributes to deforestation, soil erosion, and potential river course alteration.
