In a written reply to a question in the Lok Sabha today, Union Minister of Science & Technology, Earth Sciences, Dr. Jitendra Singh informed that five states of Uttar Pradesh, Bihar, West Bengal, Meghalaya and Nagaland have shown significant decreasing trends in southwest monsoon rainfall during the recent 30 years period (1989-2018). This data was obtained from “Observed Rainfall Variability and Changes”, published by IMD in January 2020.

 

Source: IMD

In the last 30 years (1989-2018), Nagaland state received the most rainfall in July (30 percent of SW monsoon rainfall), followed by August (27 percent), June (24.0 percent), and September (20 percent). The contribution of the SW monsoon rainfall to the yearly total is 68%.

 

It was also discovered that districts in Nagaland’s northern and southwestern regions receive more rainfall than districts in the state’s southern and eastern regions. Kiphire and Phek experienced less rainfall throughout the monsoon season, including the SW monsoon season.

 

Rainfall in Kohima, Mon, Mokokchung, Zunheboto, and Kiphire districts are dramatically decreasing during the SW monsoon season and on an annual basis. Dimapur, Tuensang, and Longleng districts, on the other hand, showed a significantly increasing trend in mean rainfall for the SW monsoon season.

 

The spatial structure of the average frequency of heavy rainfall days for the SW monsoon showed that districts Mon and Phek have the lowest frequency of heavy rainfall days.

 

The annual spatial pattern in the average frequency of heavy rainfall days showed that district Mon and a portion of Phek, Kohima have the most rainfall days (2.5-4 days).

 

The average number of rainy days for any station or district does not exhibit a statistically significant trend in June, July, or August. For one station from each of the districts of Phek and Kohima, the frequency of rainy days showed a statistically significant rising (downward) trend for the month of September as well as the SW monsoon season. However, just one station from the Kohima district exhibited an annual declining tendency.

 

No significant trend in frequency of heavy rainfall days for the month of June and August was observed. However in July, one station each from Phek district showed an upward trend in frequency of heavy rainfall days.

 

But in the month of September, one station from Peren district depicted a statistically significant decreasing trend in heavy rainfall days.

 

Meanwhile in Mon district, one station indicated a statistically significant downward trend in dry days in the month of July and August.

 

 

Mokokchung Times

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