New Scientist Australia - 10.08.2019

10 August 2019 | New Scientist | 5

DAMS are typically built to cope

with once in a century floods. But

global warming is raising the odds

of extreme events and therefore

the chances of dams failing too.

“The 1-in-100-year event is

perhaps happening every five

years,” says Roderick Smith at

Imperial College London. “I’m

absolutely convinced that it is

due to climate change.”

On 1 August, 1500 people from

the UK town of Whaley Bridge

were asked to evacuate after

damage to a dam built in 1831

(pictured). Problems began when a

section of the spillway slope where

water drains out of the reservoir

was damaged after heavy rain. The

immediate danger has passed as

the reservoir behind the dam has

been partly emptied into rivers by

using pipes and pumps.

The Whaley Bridge incident is

similar to that at the Oroville dam

in California in February 2017.

Both are earthen dams where

excess water flows over the top of

the dam and down a concrete-

lined spillway. If this concrete is

damaged, the water flowing down

the spillway can rapidly erode the

earth underneath, leading to the

entire dam wall collapsing

There is a much greater chance

of this happening when extreme

rainfall or snow melt leads to very

high water flows into already full

reservoirs.

A 2018 study concluded that

climate change exacerbated the

high water flows that led to the

erosion of the Oroville dam

spillway, which resulted in the

evacuation of 190,000 people

and repairs costing $1.1 billion.

The role that climate change

may have played at Whaley

Bridge isn’t yet clear.

There haven’t been any serious

dam collapses in the UK since the

Eigiau and Coedty dams failed in

1925, killing 16 people. After that,

regular inspections by qualified

engineers became mandatory.

Globally there have been at least

40 dam failures since 2000. The

most recent was the Tiware dam

breach in India on 2 July after

heavy rain. At least 19 people died.

The worst disaster was in 1975,

when around 170,000 died after

China’s Banqiao dam gave way. ❚

A UK town has been evacuated after damage to a dam risked disaster.

The likelihood of such events may be rising, reports Michael Le Page

Deforestation

Bolsonaro hits out

over Amazon data

BRAZIL’S president Jair

Bolsonaro has fired the

director of the nation’s

space agency INPE. Ricardo

Galvao was sacked after

he and his colleagues

revealed that deforestation

in the Amazon has increased

since Bolsonaro took power

in January.

More than 3700 square

kilometres of forest have

been cut down so far this

year, according to INPE, a

figure which is backed up by

other countries monitoring

the region. But Bolsonaro

claimed that the INPE

numbers were a “lie” and

were released to harm

Brazil’s reputation. ❚

Michael Le Page

Chemistry

Metal tongue has

a taste for whisky

AN ARTIFICIAL tongue may

one day help tackle the

counterfeit alcohol trade.

Alasdair Clark at the

University of Glasgow, UK,

and his colleagues built the

device using two different

types of metal taste buds.

To use it, they pour whisky

over the metals and measure

how light is absorbed

(Nanoscale, doi.org/c85z).

This allowed them to

tell apart samples of the

same brand of whisky aged

in different barrels with

more than 99 per cent

accuracy. The tongue could

also differentiate whisky

samples that had been aged

for 12, 15 or 18 years. ❚

Staff and agency

The trouble with dams

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