Impact of El Nino and La Nina events on climatic conditions and rice-wheat productivity in Punjab
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Agriculture in India is mostly rainfed and is greatly influenced by Indian Summer Monsoon Rainfall
(ISMR). It contributes to about 75 per cent of the total annual rainfall. El Nino, a phenomenon during
which unusually warm water appears in the eastern Pacific Ocean has inverse relation with Indian
summer monsoon rainfall. The historical data of different meteorological parameters (maximum
temperature, minimum temperature, relative humidity, sunshine hours and rainfall) for different
locations of Punjab viz. Amritsar (1971-2017), Ballowal Saunkhri (1984-2018), Bathinda (2001-2018),
Ludhiana (1971-2018) and Patiala (1971-2018) were collected from the Department of Climate Change
and Agricultural Meteorology, PAU, Ludhiana and Met Centre, India Meteorological Department. The
rice-wheat productivity data were collected from indiastat.com and Statistical Abstract of Punjab. The
data related to groundwater table (1998-2017) were collected from the Central Ground Water Board,
Punjab. The El Nino/ La Nina events data were retrieved from Golden Gate Weather Services.The
decade wise monthly analysis of maximum temperature showed increasing trend at Ballowal Saunkhri,
Ludhiana and Patiala during all months except January, June and September whereas at Amritsar and
Bathinda decreasing trend was observed in most of the months. The minimum temperature was found
to be increasing at all the locations. The mean relative humidity showed increasing trend at Amritsar,
Ballowal Saunkhri, Bathinda and Patiala whereas at Ludhiana few months showed negative mean
relative humidity. The increasing trend in rainfall was observed at Amritsar and Ludhiana during all
months except May, July, November and December whereas Ballowal Saunkhri and Patiala showed
decreasing trend in most of the months. Inter season rainfall variability during kharif season mostly
occurred in El Nino years at all locations except at Ballowal Saunkhri. The heavy rainfall events
occurred more frequently compared to very heavy and extremely heavy rainfall events at different
locations. Intra season rainfall variability between different seasons was highest during post monsoon
season followed by pre monsoon season. Drought indices standardized precipitation index (SPI) and
aridity index (AI) were calculated. SPI showed that El Nino year was more related with annual and
kharif deficit years. Aridity index showed that El Nino years were warm and dry compared to La Nina
and neutral years and in recent years Ballowal Saunkhri showed shift towards warm and dry conditions.
The ground water table level showed significant decrease at different locations of Punjab. The
relationships between groundwater table and rainfall indicated that continuous deficit rainfall years led
to decline in groundwater table. The correlation between wheat grain yield and diurnal range of
temperature was negative at all the locations except at Ballowal saunkhri.
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