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ONSET:-The
period characterizing an abrupt rise in the normal rainfall
curve is taken to define the onset of monsoon. In Maharashtra
the normal date is 7th June. The Onset is very critical for
sowing of Kharif Crops. Delay in Onset hampers the sowing
progress.
(Click to recommended sowing
dates)
(Click to contingency planning)
(Click here to see Map of On-set
dates)
WITHDRAWAL: -
Is defined as the end of rainy season on the last date on which
a threshold amount was exceeded. Another means of finding out
the end of rains was to use the 1st occurrence of a
long dry spell after a specific date. Withdrawal of monsoon
mainly affects the status of residual moisture to be used in
Rabi season.
DRY
SPELL: -
Dry spell like the drought means from the agronomic point of
view, a dry spell is not a drought of climatic magnitude but a
period of a few days or weeks. A dry spell is interval between
two wet spells of seven day magnitude with at least 25 mm of
rain. Five of these seven days must have rainfall of more than 1
mm or more. Dry spells at critical crop growth stages affect the
growth and the ultimate production of crop.
INTENSITY:-Amount
of rainfall occurred per unit period of time. Heavy intensity of
rainfall causes soil erosion and crop losses. It is very
important for flood management and design of soil and water
conservation structures.
WET
SPELL :-
Wet spell
is defined as a rainy day �x� mm of rainfall or seven days spell
where the total amount of rainfall equals to x mm or more and
the condition that 3 out of these seven days must be rainy with
rainfall of more than 2.5 mm of each day.
CRITICAL DRY SPELL: -
Is defined
as the duration between the end of the wet spell and the start
of another wet spell, during which a fifty percent depletion of
available soil moisture occurs in the top 50 cm. Soil layer. |
