The Indian Meteorological Department has released a 'new normal' rainfall update for the country. While the new updated rainfall normal measures a decline in annual rainfall in the country, the monsoon rainfall in Odisha shows a decline in quantity.
As per the IMD report, the annual rainfall measured in the country for the period 1961 to 2010 had been 1176.9 mm (117.69cm). The updated rainfall data shows that in the period 1971-2020, the annual rainfall received by the country is recorded at 1160.1 (116.1). The new normal rainfall data, therefore, has recorded a decline of 1.59 cm of rainfall in the country.
The data released by IMD documented a drop in monsoon rainfall in the country. Sample the following table.
During the period 1961- 2010, the country had received an average rainfall of 880.6 mm during the monsoon period (June - Sept). However, the updated rainfall data measures the average rainfall during the monsoons in the period of 1971-2020 at 868.6 mm.
Data analysis shows the monsoon rainfall in the country shrinking by around 1.2 cm during the period 1971-2020. The drop in precipitation quantity is attributed to erratic monsoon in the last decade and a half.
Be it monsoon, pre or post-monsoon or even winter, the prevailing trend has been that the rainfall has turned frugal in the country. A drop in quantity is measured in every season.
The SW monsoon rainfall in the country has been on the decline since the decade of 1971-80. but the horror story is during the last two decades of 2001-2011, the departure from normal monsoon rainfall had been a massive 4.8 percent. In the decade 2011-2020, the decline is 3.8 percent.
Data with IMD revealed that the country had recorded the highest 6.1 percent departure from mean decadal rainfall during the SW monsoon period. The country had recorded a bountiful monsoon during the period 1921-1960. After a continuous rise for three consecutive decades, monsoon rainfall has taken a plunge from the decade 1951-60. (see the above image)
The IMD data pops up a changing trend of rainfall in the State. In the period 1961-2010, the mean rainfall during the SW monsoon period in the State had been around 1160.2 mm rainfall.
As per the new updated normal rainfall released by IMD, the mean rainfall measured for the period 1971-2020 had remained between the range of 1000mm-1600mm. A detailed analysis by IMD shows that in the period of 1971-2020, the State had recorded a rainfall that had been in the range of (-20mm to 10mm).
The explanation of the above numbers here is the mean rainfall during the long period of 1971-2020 in the monsoon period had been deficient in the State by 20mm and above normal by only 10mm.
A glance at the above data clearly shows the drop in monsoon rainfall in the State is higher at 20mm than the rise of 10mm.
Odisha Vs Other States
A comparative analysis of rainfall in SW monsoon data shows that states like major parts of Gujarat, Rajasthan, Madhya Pradesh and Andhra Pradesh have recorded higher rainfall in Monsoon during the period of 1971-2020. The states have recorded excess rainfall to the tune of 33 percent. (see the image below).
Dry or Deluge In Odisha?
Unlike the country, the annual rainfall in the State has not recorded a drop. The mean annual rainfall measured in the State for the period 1971-2020 had been higher by around 10mm. The mean annual rainfall recorded in the State during the period 1961-2010 had been 1447.8mm.
But the significant pointer for the State has been that mean rainfall has turned negative (-5mm) in winter. The precipitation quantity in pre-monsoon had been in the range of (-2mm) to (2mm).
However, it is in the post-monsoon season (means during Oct-Dec), mean rainfall in the above mentioned period had been up by nearly 10 mm.
A deficient monsoon and surplus post-monsoon do hold ominous portends for the agrarian State. Declining monsoon rain means erratic rainfall during the sowing season, and surplus rainfall in Oct-Dec means crop loss during the harvesting period.