Urban floods intensifying as rural areas drying up around world

Source: Xinhua| 2017-08-15 14:54:15|Editor: ying
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By Will Koulouris

SYDNEY, Aug. 15 (Xinhua) -- After conducting a landmark study of global rainfall and river systems, scientists in Australia said Tuesday they have discovered that while urban areas are increasingly being flooded, rural areas are drying up around the world.

Australian scientists from the University of New South Wales (UNSW) analyzed data from over 43,000 rainfall stations - and 5,300 river monitoring sites - across 160 countries worldwide, and said that the data shows that climate change is a factor in the worsening of river flows.

Ashish Sharma, professor of hydrology at the UNSW School of Engineering told Xinhua on Tuesday that his research showed a direct link between warmer temperatures and more intense storms, but that flooding was actually decreasing - which despite what it may appear to be, is a major concern.

"This was something that was quite surprising to us, because typically when you expect the rainfall to intensify, you should see a corresponding increase in the floods," Sharma said.

"What we figured out is that the warmer temperatures are making the soils much drier than what they were before. Now these soils don't really matter in an urban context, because in the city you hardly have any soil. But, you do have a lot of soils that act as a buffer to the big intense storms in rural areas."

With the overnight mudslides in Sierra Leone that have left a death toll estimated into the hundreds, Sharma said that while there could be many factors in play in that horrific incident - such as deforestation - in a broader context, the warmer temperatures associated with climate change could possibly be connected.

"As a result of warmer temperature, the atmosphere holds more moisture, when it comes down, it falls with greater intensity," Sharma said.

"So when you have the higher, more intense, energy laden rainfall - if the soil is completely saturated, that provides that added turbulence that can possibly create these type of events."

The professor was adamant that the data that he collected demonstrates not an isolated, but a worldwide issue for concern - with this current study being the first of its kind to provide a clear assessment of the dangers of allowing adequate water controls to be brushed to the wayside.

"This is a huge problem, this is the first study that assesses this type of an impact across the world. We have taken data from 160 countries, lots of river bases. Nearly 50,000 rain gauges have been assessed," Sharma said.

"So we are actually using data that people have been collecting religiously, very systematically for the last 50, 60, 70 years - essentially if anybody wants to reassess our results, they just have to download the data and see, that the data is showing intensification of rain universally across the world."

But the same data is showing that common floods, the ones which are necessary to ensure water supply are on the decrease, which puts pressure on already dwindling supplies of fresh water across the world - and marginalizes many on which their survival depends.

"What we have to do is to take a step back and see what we did 50, 60, 100 years ago - to make places livable," Sharma said.

Places like Arizona, and California were prime examples of this, according to Sharma, who said that despite all conditions indicating those areas should not be able to sustain such vast amounts of people, civil engineers planned for the long term water needs of ever expanding populations.

"With the Netherlands, half of the country is below sea level. Essentially engineers have built big engineering projects to make it possible for people to live there. In Australia, one of the big engineering wonders of the world is the Snowy Mountains Scheme," Sharma said.

"So all of these things have been done many years ago because conditions were not exactly how humans, the people who were living there, wanted them to be, and now the conditions are changing," he added.

"The atmosphere is warming up, it is holding more moisture, it is sending down more intense bursts of rainfall - we just have to reengineer a lot of things on ground again with the same intensity as we did so many years back."