Are the heavy summer showers in Kerala a cause for serious worry?

These are strange times and any major change in the climatic pattern, even if it looks welcome, can cause serious unease.

Possibly why the unprecedented excess in summer showers this time in Kerala, though it has kept aquifers and wells from drying up during the summer, is largely seen as a portent of some major disaster waiting to happen, a bad omen of sorts.

Since March, Indian Meteorological Department figures show that Kerala had excess rainfall of 40 per cent. Usually, summer showers are patchy. They arrive in great fury, to the accompaniment of scary sound and light effects, but never really seemed motivated enough after the initial promise.

Last year, for instance, Kerala officially had normal summer showers, even a slight excess of seven per cent. But there were six districts, nearly half of Kerala, that had deficient pre-monsoon rains.

But this time, testifying to the uncharacteristically even nature of the pre-monsoon showers, there was not a single district in Kerala that had deficient summer showers.

Three districts (Ernakulam - 61 per cent, Kottayam - 80 per cent, and Pathanamthitta - 103 per cent) had, what in IMD language is called, "large excess" rainfall.

Seven districts – Kannur, Idukki, Kasaragod, Kollam, Malappuram, Thiruvananthapuram and Wayanad – had "excess" rainfall, or more than 20 per cent above the normal. The remaining four districts – Alappuzha, Kozhikode, Palakkad and Thrissur – had normal rainfall.

Heavy summer showers and floods

Last year, when pre-monsoon showers were normal, the southwest monsoon was also normal. Therefore, does excess summer showers warn of another flood year?

The fear has been triggered by the fact that during 2018, the year of the deluge, Kerala had excess summer showers. A reassuring fact is, the 2018 “summer excess” was only a slight excess, below 10 per cent, not the kind of prodigious showers Kerala has experienced this time.

The IMD's monsoon forecast should also have put fears to rest. It predicted a normal monsoon this year. Climatologists have also not found a link between summer showers and the behaviour of monsoon.

There were heavy summer showers in 2008. Wayanad had even witnessed floods in March that year, but the subsequent monsoon was poor. There were poor summer showers in 2011, but the southwest monsoon was healthy that year. In 2016, poor summer showers were followed by poorer southwest and northeast monsoons.

Summer showers, in short, do not carry the DNA of the monsoon in its womb.

Summer showers and early monsoon

Yet, these pre-monsoon showers could influence the southwest season.

S Abhilash of CUSAT's Department of Atmospheric Sciences said excess summer rainfall, like this year's, could cause an early onset of the monsoon.

Senior IMD officials, though they were unwilling to commit at this point, said the existing conditions (May 12 and 13) hint at an early monsoon. The IMD might even declare the onset before May 20.

Some of the conditions required to declare the onset have already come into being. Here are two of them: The westerly winds have already gathered speed over the Arabian Sea and in the last two days at least 70 per cent of the 14 rain gauge stations across Kerala had recorded more than 2 millimetres of rainfall.

Little girl's cooling effect

According to Abhilash, it was the La Nina (the little girl) effect that gave Kerala good summer showers. La Nina is a phenomenon that works in the reverse direction of the more common El Nino, a Spanish word that means 'little boy', the exact opposite of La Nina.

When there is El Nino, moisture-laden winds that cause rains move eastwards, away from the Indian sub-continent. When La Nina happens, the moisture-laden winds move westwards, cooling Kerala's summer.

Rising water level in dams

Nonetheless, heavy summer showers followed by heavy southwest monsoon could be problematic for Kerala. “If this happens, the water level in our dams should be managed with great care and skill,” said environmentalist S P Ravi of Chalakkudy Puzha Samrakshana Samithi.

Good summer showers have already reduced Kerala's daily consumption during summer. This May, daily consumption is lower than during the corresponding periods in the last two years. This saves power but would accumulate water in the dams. “It is time to step up hydel production so that our reservoirs have only the optimum level of water in them,” a top KSEB engineer in the generation wing said.

Warning signs are very near

At the moment, the water level in dams is below the optimum level, though not far below. A heavy burst of rain can change the level in no time.

The Idukki reservoir, for instance, has water up to 2,333.72 feet on May 12. The maximum height allowed on the day is 2,400 ft. But this is just 58 ft below the point when the 'Blue Alert', the first warning, has to be issued.

Water level in Pampa is even closer to the danger mark. On May 12, it was 986.33 ft, which is just 21 ft below the point when the 'Red Alert', the final warning, has to be issued.

Here, therefore, is the one big disadvantage of good summer showers: Kerala's dams begin to flirt with danger even before the monsoon strikes.

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