The northern region, agricultural hub of the country, has witnessed huge deviations in rainfall variability in the past decades. In a study, it has been observed that year to year rainfall variability is very large in many parts of Punjab and Haryana with a deviation of more than 35 per cent of normal for minimum rainfall.
“The seasonal analysis showed that the rainfall trend is decreasing in monsoon, post monsoon and winter seasons, whereas an increasing trend of seasonal rainfall during pre-monsoon season was observed in parts of Haryana,” revealed a study paper presented at ‘TROPMET 2015’ that concluded on Wednesday.
The States of Punjab and Haryana which are said to be the granaries of India, have seen large number of years with deficit monsoon rainfall in past two decades. Punjab has seen just two years with above normal monsoon rainfall since 1999 while Haryana had seen just four such years with above normal rains in last 16 monsoons.
Another research paper which provided an analysis of trends and variations in rainfall for Himachal Pradesh and Punjab revealed noticeable variations in different climatic zones with increasing rainfall in the cold desert zone and hot-humid tropical region while decreasing trends in cold and wet climatic region. The overall analysis indicated random fluctuations in inter-annual variations and more variable rainfall which may lead to increased extreme events and increased vulnerability of Punjab and Himachal.
In an attempt to study the rainfall pattern and its variation over time and space in Haryana, Punjab and Himachal Pradesh, the past decades data were analysed. Means and trends of annual, seasonal and monthly precipitation were also analysed at different time scales. For Haryana, the four locations selected for the study included Hisar, Sirsa, Ambala and Karnal well representing the climatic zones of Haryana. During the data analysis, decreasing rainfall trend was observed and the rate of decrease is higher during the recent years.
The similar trend was observed in case of rainy days. Decline in rainy days was also higher in monsoon season. The change in the distribution pattern of the rainfall is also noticed. The average annual rainfall at Hisar is 451.8 mm with standard deviation of 158.8 mm and coefficient of variation of 35.1 per cent.