30 August 2017

The flooding has already claimed in excess of 1,500 lives

The cause of the floods in southern Asia

Overstroming Nepal

Heavy rainfall and huge floods are taking their toll on southern Asia. In total, over 1,500 lives were lost in Nepal, Bangladesh and India, with more trouble still to come. Flood expert Niko Wanders explains the cause.  

Monsoons are annual phenomena in southern Asia, during which period rainfall is extreme in both frequency and intensity. This year, however, the monsoon is much more severe than usual. ‘Global warming has increased the chances of this extreme weather’, says Niko Wanders. ‘Rising temperatures mean an increase in the evaporation of water and therefore an increase of rainwater within the atmosphere. Furthermore, the warmer it is, the more precipitation in the Himalayas will take the form of rain rather than snow. Whereas snow usually remains in place for a while, rain immediately flows further downwards.’

‘Global warming has increased the chances of extreme weather’

According to Wanders, the affected areas suffer from storm clouds blowing inland from the Indian Ocean. ‘These clouds eventually hit the Himalayas, which they cannot pass over due to their weight. As a result, the huge clouds release all of their contents on the one side – in this case, Nepal, India and Bangladesh. Over an eight-day period, 1,252 millimetres of rain were reported. That is a truly unprecedented figure – roughly equal to the precipitation that falls over the course of a year and a half here in the Netherlands.’

Sandbags

What's more, the local weather services are neither funded nor prepared as well as they are here. ‘European weather models have a fortnightly forecast’, Wanders notes. ‘A warning of extreme weather ten days ahead will result in raised threat levels for the major European rivers. National water services will be notified seven days in advance, while helicopters and sandbags will be on standby three days before the extreme floods. None of these services are available in southern Asia. In addition, Dutch river embankments are high enough that floods are only expected to occur once every 1,250 years. The same can't be said of the arrangements over there.’

Drought

Dryer spells are not forecast for the victims of the flooding in southern Asia any time soon. ‘It's clear from the models that plenty of precipitation will continue to come down there in the next month. To make matters worse, the rain falling over India, for instance, would usually be distributed over other regions as well. There would normally also be a monsoon in neighbouring Myanmar around this time, but that country is now experiencing extreme drought.’

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