Though the Indian Meteorological Department (IMD) has predicted a near-normal monsoon this year, the situation is likely to be complex amid the possibility of spatial variation in the rainfall due to the impact of climate change and lesser water storage reported from reservoirs in the eastern and western regions compared to last year.

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The IMD last month predicted that monsoon will be "near-normal" this year with an expected rainfall of 96 percent. However, Skymet Weather said that the monsoon was likely to be "below normal" to the extent of 93 percent.

According to Skymet Weather, the impact of El Nino would be more in June and July but will decline by August and September.

While the IMD has predicted two per cent probability of "excess" rainfall and 10 percent for "above normal" rainfall, Skymet predicted zero per cent chances of both.

El Nino is a part of a climate pattern that occurs when sea surface temperatures in the tropical Pacific Ocean rise to above-normal levels for an extended period of time. It influences temperature and rainfall across the global.

The IMD had predicted around 96 percent well-distributed rainfall, at a moderate error estimate of plus-minus five per cent of the Long Period Average.

The predictions assume significance in the wake of the Water Resources Ministry data, released on Thursday, which shows that the storage levels in 91 major reservoirs across the country have declined by one per cent.

The water available in these reservoirs for the week ending May 2 was 40.592 BCM (billion cubic metres), which is 25 percent of total storage capacity of these reservoirs. There was 26 percent water in the reservoirs for the week ending April 25.

Rajasthan, Jharkhand, West Bengal, Tripura, Maharashtra, Uttar Pradesh, Chhattisgarh, Andhra Pradesh and Kerala were the states that reported lesser storage than last year for the corresponding period.

The Water Ministry data shows that in the northern states of Himachal Pradesh, Punjab and Rajasthan and Central states of Uttar Pradesh, Uttarakhand, Madhya Pradesh and Chhattisgarh, the present storage was better than last year's and also better than the average storage in the past 10 years.

In the eastern states of Jharkhand, Odisha, West Bengal and Tripura, the storage during current year was less than the corresponding period of last year but was better than the average storage of the past 10 years.

In western states of Gujarat and Maharashtra, the current year storage was less than last year's storage and also less than the average storage of past 10 years during the corresponding period.

In the southern states of Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil Nadu, the storage was better than the corresponding period of last year but less than the average storage of the past 10 years during the corresponding period.

Weeks ahead of the arrival of monsoon, there are reports of several states, including Andhra Pradesh, Telangana, Gujarat, Jharkhand, Karnataka and Maharashtra facing severe water scarcity.

The situation is only likely to worsen in the years ahead with a Ministry of Earth Sciences study showing significant changes in annual rainfall in some meteorological sub-divisions, though there are no changes in the all-India rainfall.

The climate change assessment, done by the Intergovernmental Panel on Climate Change (IPCC), links the growing frequency of extreme rainfall to global warming and warns that the frequency of such events may only increase in India.

The data shows decreasing trends in rainfall over Kerala, east Madhya Pradesh, Jharkhand, Arunachal Pradesh, Nagaland, Manipur, Mizoram and Tripura, and increasing ones over coastal Karnataka, Maharashtra and Jammu and Kashmir.

There is a general increase in the frequency of extreme rainfall (heavy rainfall events), especially over Central India, during the monsoon season.

First Published:May 4, 2019 1:53 PM IST