2. Benchmarks of Normal Monsoon Behaviour and Possible Shifts
i) South-west monsoon over different parts of the country sets in at different times between May and September. Its normal onset period over Kerala is around 29th May and by June 1st week, the northern limit of monsoon passes over Karnataka, Manipur and Tripura. By the second week of June, the limit passes through Mumbai, Kolkata and covers the states of Assam and Arunachal Pradesh.
ii) The onset over the north-western parts of India is around last week of June to the first week of July and covers the entire country within about 30 days. Similarly, monsoon withdrawal starts from the second week of September over the northern parts and around 15th October, the south-west monsoon conditions cease to operate.
iii) Breaks in monsoon situations result from the change in the track of tropical depressions from Bay of Bengal and their number in a given month give rise to dry spells over certain sub-divisions in any given year. It happened in 2009 due to cyclone called Aila.
The four broad scenarios for which one has to plan for contingency are:
I. Delayed onset
Maximum of three weeks from normal date for the given region. This happened in North-west India in 2002 and North West and North East India in 2009.
II. Early onset and sudden breaks.
This scenario happened in some parts of the country in 2009.
III. Early withdrawal of monsoon
By last week of August and causes stress during maturity of crops.
IV. Delayed withdrawal or extended monsoon.
May damage matured crops at the harvesting time.
V. Various permutations and combinations of above four scenario.
Complexities of management increases.
Ministry of Agriculture, GOI.
Submitted by sugatha on Mon, 07/09/2009 - 16:22