Rainfall

June Aug 2024: District wise rainfall in India’s SW Monsoon

In the just concluded month of Aug 2024, India received just 295.2 mm (162.7 mm or 36.2% below normal in Aug 2023[i], 263.8 mm in Aug 2022, 3.5% above the normal[ii]) or 15.8% above normal rainfall of 254.9 mm as per India Meteorological department (IMD). In Aug 2021, the rainfall was 195.9 mm[iii], about 24.13% below normal and  in Aug 2020, the rainfall was 327 mm[iv], or about 26.6% above normal.

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Cauvery · River Water Disputes

Lessons for Other River Basins from the Cauvery Dispute

Guest Article by Prof Bhakti Devi

Numerous articles have cropped up explaining the reason behind the Cauvery water inter-state dispute. A remarkable thing to note in these explanations is that every one of the articles focuses on the volumetric allocation of water. Even the documents relating to legal agreements between the two states on how the water of the Cauvery River will be shared focus on the volumetric distribution. Which, on the surface, appears completely logical but seems illogical when you understand the science of how a river gets its water which is the elephant in the room.

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Monsoon · Rainfall

June July 2022: District wise rainfall in India’s SW Monsoon

In the just concluded month of July 2022, the second month of India’s South West 2022 monsoon, India received 327.7 mm rainfall, 16.8% above the normal July rainfall of 280.5 mm as per India Meteorological department. In July 2021, the rainfall was 266.1 mm[i], about 6.7% below normal and  in July 2020, the rainfall was 257.1 mm[ii], or about 9.9% below normal.

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Dam Safety

Tamil Nadu: Thalavanur check dam collapsed twice within a year

Thalavanur check dam collapsed[i] in morning hours of November 9, 2021. This is the second time the check dam has faced significant damages within a year of its construction. Before this, the same check dam broke down in January, 2021. The first collapse took place 5 months after its inauguration on September 19, 2020. Its construction was started in April 2019.

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Monsoon · Rainfall

Heavy Rainfall in India in Oct-Nov 2021

India has seen rather heavy rainfall in October and November 2021, with October All India Rainfall being 33% above normal and November rainfall being record breaking 86% above normal. The combined Oct + Nov Rainfall was 48% above normal, and by Dec 7, as we write this, it is already 53% above normal for the period from Oct 1 to Dec 7, 2021.

While lingering South West Monsoon brought large part of the excess rainfall in first half of October, the unusually active North East Monsoon with continuous supply of moisture from Bay of Bengal has been the main reason for the high rainfall since late October. The onset of La Nina has also contributed to this and with La Nina forecast to remain in place till March 2022, we are in for continued wet spell in South India, it seems. IMD has already forecast above normal rainfall in South Karnataka during Dec 2021 to Feb 2022.

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Monsoon · Rainfall

June July 2021 District Wise SW Monsoon Rainfall in India

In the just concluded month of July 2021, India received 266.1 mm rainfall, that is 6.73% below normal July rainfall of 285.3 mm, as per India Meteorological Department (IMD). This is in contrast with June 2021 rainfall, that was almost 11% surplus over Normal rainfall. Not only that surplus has been wiped out by the July 2021 deficit, the overall June July 2021 rainfall now is 449 mm, or about 0.7% below normal rainfall of 452.2 mm, as per IMD.

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Monsoon · Rainfall

June 2021: District wise rainfall in India’s SW Monsoon

In the just concluded June 2021, the first month of India’s South West 2021 monsoon, India received 182.9 mm rainfall, 10.96% or about 11% more than the normal June rainfall of 166.9 mm as per India Meteorological department. In June 2020, the rainfall was 196.9 mm, or about 18% above normal and in June 2019 it was 33% below normal.

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Indian Meteorological Department · Rainfall

Pre Monsoon 2021 season – State Wise, District Wise Rainfall

In the just concluded pre monsoon season (March 1 to May 31, 2021) India received 155.2 mm rainfall, 18% above the normal rainfall of 131.7 mm as per the India Meteorological Department (IMD). This is similar to the case in 2020[i] when India received 158.5 mm or 20% above normal rainfall.

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Rainfall

District wise Winter 2021 Rainfall in India

In the just concluded Winter Season (Jan 1 2021 to Feb 28 2021), as per India Meteorological Department (IMD), India received 32% below Normal Rainfall. The Normal rainfall in this two-month season is supposed to be quite low at 40.8 mm, but the actual rainfall was just 27.8 mm, which means rainfall was less than 0.5 mm per day in the season. Out of this the Rainfall in January 2021 was 20.2 mm, 17% above the normal rainfall of 17.3 mm. So in February 2021, the rainfall was 7.6 mm, against the normal rainfall of 23.5 mm, so the February rainfall was 68% below normal!

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Rainfall

Post Monsoon 2020: State wise Rainfall

According to India Meteorological Department (IMD), during the just concluded Post Monsoon Rainfall for 2020, that included rainfall during Oct-Dec months, India received 124.6 mm rainfall, 0.64% above the normal rainfall of 123.8 mm during the period. As per IMD[i] definition, the rainfall was thus normal.

This three-month period from Oct 1, to Dec 31 includes the North East Monsoon that mainly affects parts of South India including Tamil Nadu, Puducherry, Rayalseema, parts of Karnataka and Kerala. IMD declared on Jan 1, 2021 that the of NE Monsoon ended on Dec 31, 2020 with normal overall rainfall: TN had 6% above normal, Karnatak 13% above normal, Puducherry 32% above normal, Andhra Pradesh 33% above normal. However, Lakshadweep had 9% below normal and Kerala 26% below normal. This monsoon provides 48% of the annual rainfall of TN so it is most imp for that state.

The rainfall revived only towards the end of November, mainly due to two consecutive cyclones — Nivar and Burevi — both of which developed in the Bay of Bengal. While Cyclone Nivar crossed the coast close to Karaikal near Puducherry and brought heavy showers for the east and coastal districts of Tamil Nadu, Cyclone Burevi weakened before it reached land.

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