In the just concluded month of August 2021, the rainfall in India was a massive 24.13% below normal. Actual rainfall was 195.9 mm, compared to normal rainfall of 258.2 mm, as per figures from India Meteorological Department (IMD). Contrast this with the rainfall in August last year, at 327 mm, was 26.6% above normal, ,and 44 year high. Even in July 2021, the rainfall was much higher at 266.1 mm, 6.73% below normal. In June 2021, the rainfall was 182.9 mm (10.96% above normal), not much below the August 2021 rainfall, when August is supposed to have much higher rainfall than June.
|Actual Rainfall, mm||Normal Rainfall, mm||% Departure from normal|
|June 2021||182.9||166.9||+ 10.96|
|July 2021||266.1||285.3||– 6.73|
|Aug 2021||195.9||258.2||– 24.13|
|June-Aug 2021||644.9||710.4||– 9.22|
The figures also show how wrong were the rainfall forecasts of IMD. IMD had predicted in June normal monsoon for the country with rainfall 101% of normal. Now after the August rainfall figures are out, IMD says the monsoon rainfall will still be normal, but closer to 96 as it forecasts that the September 2021 rainfall will be above 110% of Long Period Average Rainfall of 170 mm. In the past, out of 15 deficient August rainfall years (deficit over 15%), only in four (e.g. in 2005) the season rainfall was normal, in 9 cases it was deficient and in 2 cases (e.g. 2001) it was below normal. Let us see how accurate is this fresh forecast of IMD.
In August 2021, Central India witnessed over 39% deficit, North West India saw 31% deficit and Southern Peninsula experienced 10% deficit. M Mahapatra, Director General of IMD confessed that IMD in its forecasts could not pick up the magnitude of deficiency in states like Gujarat and Odisha, leading to wrong forecasts. He said the rainfall was as per the forecast till second week of Aug, but declined thereafter. Mahapatra did not rule out crop damage due to heavy rains in September, but expressed IMD’s inability to identify such areas.
State wise rainfall As can be seen from the map above, of the 37 States and Union Territories (UTs) of India, three states had Excess rainfall in June-Aug 2021. These include Telangana (highest surplus of 28%), Tamil Nadu and Andhra Pradesh. 23 states and UTs had Normal rainfall and eleven had Deficit rainfall. The highest deficit is in Manipur (-58%), followed by Gujarat (-50%), Ladakh (-52) and Odisha (-29%). The Highest rainfall was in Goa at 2566.8 mm and the lowest rainfall was in Ladakh at 13.7 mm.
Sub Division wise rainfall IMD divides the country into 36 meteorological sub divisions, of which four had surplus rainfall during June-Aug 2021 three month period, the highest surplus was surprisingly in North Interior Karnataka, followed by Telangana, Rayalseema and Tamil Nadu plus Karaikal. Twenty one sub divisions had normal and eleven had deficit rainfall. The highest deficit was in Saurashtra and Kutch at 53%, followed by Gujarat region at 47% deficit. The lowest rainfall was in Western Rajasthan at 169.2 mm and highest rainfall in Konkan and Goa at 2792.5 mm.
River Basin wise rainfall While IMD reporting river basin wise rainfall is good, the reporting remains most callous and hence unreliable. IMD seems unable to understand the importance of reporting rainfall as per river basin, which is in fact even more important than reporting by states or meteorological divisions (incidentally, there a lot of question marks the way IMD has divided the country into these sub divisions.)
For June-Aug 2021 three months, IMD continues to show NO RAIN in a number of sub basins including Upper Brahmaputra, Imphal & Others, Lower Bhima & East flowing rivers between Krishna and Pennar. This is clearly an impossibility and shows how callous IMD is. It also shows NO DATA for Jhelum and Upper Indus. The highest rainfall has been reported for Lower Brahmaputra basin at 2971.1 mm, which is 99% above normal. It is interesting to note that while Gujarat claims lower inflow into the Sardar Sarovar Dam on Narmada from its catchments upstream, IMD reports that Narmada basin has 981.8 mm rainfall, 19% ABOVE NORMAL. So big question mark either on Gujarat’s statement or IMD figures.
STATE WISE DISTRICT WISE RAINFALL: NORTH EAST INDIA: Assam
EAST INDIA: West Bengal
Odisha Highest rainfall deficiency in 23 years Odisha received only 661.1 mm of rain between June 1 and August 31 this year against a normal of 935.8 mm, a deficiency of 29 percent, the MeT Centre said.
This was the sixth occasion in the last 120 years when the southwest monsoon rain during the period has been deficient by 29 percent or more, an official release said on Wednesday (Sept. 1). The previous rain-deficient years were 1924 (636.2 mm), 1954 (646.8 mm), 1974 (658.7 mm), 1987 (641.4 mm) and 1998 (657.5 mm), the department said.
The seasonal deficit is mainly due to a large deficiency in August. Rainfall over the state during the month was 204.9 mm against a normal of 366.4 mm, recording a deficiency of 44 percent, it said. There were only three times in the last 120 years that the August rainfall was less than 204.9 mm — 1965 (187.3 mm), 1987 (190.3 mm) and 1998 (203.5 mm). https://www.moneycontrol.com/news/india/monsoon-updates-highest-rainfall-deficiency-in-odisha-in-23-years-7422951.html (03 Sept. 2021)
SOUTH INDIA: Andhra Pradesh
WEST INDIA: Goa
NORTH INDIA: Ladakh
Jammu & Kashmir