BSc.-MSc.(Integrated)

Climate change poses an emerging threat to sustainability of social and economic
development, livelihoods, and environmental management across the globe. Characterization
of the ecosystems using the AEZ concept is a good decision making approach for variety of
farming activities performed by the farmers and is a useful tool for the studying the impact of
climate change. The objectives of this study are (1) to study rainfall variability and to
determine water availability periods of Agro ecological units of southern Kerala under
different climate change scenarios. (2) To study the impact of projected climate change on
cropping pattern, crop calendar and the possible changes in the water requirements of major
cropping systems prevailed in the various Agro ecological Units of southern Kerala.
Daily rainfall data for the period 1991-2014 were collected from the India
Meteorological Department, Thiruvananthapurm. Weather cock v.1.5 was used for
converting the daily weather data into standard week, month and seasonal formats. It is also
used to compute PET and Thornthwaite water balances. CROPWAT model was used for the
calculations of crop evapotranspiration, crop water requirements and irrigation requirements
for the development of irrigation schedules under various management conditions and
scheme water supply.
The annual rainfall availability in most of the AEUs of Thiruvananthapuram, Kollam
and Pathanamthitta districts show a decreasing trend in the projected climate and an
increasing trend in Idukki, Kottayam and Alappuzha. The number of annual rainy days
generally shows a decreasing trend. The seasonal rainfall of southwest and summer monsoon
will show an increase from the current situation where as northeast monsoon and winter will
have a decreasing trend.
In projected climate of both RCP 4.5 and 8.5 there will be high probability of having
reduction in the number of months having the surplus and an increase in the number of
deficit. The crop evapotranspiration values of rice based cropping system will show a
tendency to increase. In perennial cropping systems of coconut based and rubber the
projected crop evapotranspiration will have a reduction from the present situation whereas in
coffee based cropping system the ETc will have an increasing trend.
The irrigation requirement of all the major cropping systems will increase from the
present situation except in the case of rice-fallow-fallow. The length of growing period of the
cropping season in the major rice growing areas of different AEUs are getting shorter with
slight differences among various agro-ecological units, implying a higher risk of operating
under projected climate as per RCP 4.5. The sowing date will be delayed up to three to five
weeks. It can be also observed that the crops will have to suffer water stress during the grain
filling stage and will be under heavy rains at time of harvest in almost all the considered
cases.