Page 28 - ARUBA TODAY

A28 SCIENCE
Monday 3 February 2020
As forests burn around the world, drinking water is at risk

By TAMMY WEBBER able to fire due in large creased in recent de- and other aquatic life than doubled over the past
Associated Press part to hotter, drier weath- cades, and that expansion necessary for high-quality 20 to 30 years, said Doerr,
Fabric curtains stretch er that has extended fire likely will continue through water before it reaches from Swansea University.
across the huge War- seasons, and more people the century because of a reservoirs. Already, thun- Although there might be
ragamba Dam to trap ash fewer cities and towns in
and sediment expected to the path of runoff in those
wash off wildfire-scorched areas, problems do occur.
slopes and into the reser- In Canada's Fort McMur-
voir that holds 80% of un- ray, Alberta, the cost of
treated drinking water for treating ash-tainted water
the Greater Sydney area. in its drinking-water system
In Australia's national capi- increased dramatically af-
tal of Canberra, where a ter a 2016 wildfire.
state of emergency was In the Western U.S., 65% of
declared on Friday be- all surface water supplies
cause of an out-of-control originate in forested wa-
forest fire to its south, au- tersheds where the risk of
thorities are hoping a new wildfires is growing — in-
water treatment plant and cluding in the historically
other measures will prevent wet Pacific Northwest. By
a repeat of water qual- mid-century almost 90% of
ity problems and disruption them will experience an in-
that followed deadly wild- crease — doubling in some
fires 17 years ago. — in post-fire sedimenta-
There have not yet been tion that could affect drink-
major impacts on drinking ing water supplies, accord-
water systems in southeast ing to a federally funded
Australia from the intense 2017 study.
fires that have burned more A boom floats across a small bay near the dam wall at Warragamba Dam in Warragamba, "The results are striking and
Australia, on Wednesday, Jan. 29, 2020.
than 40,000 square miles Associated Press alarming," said Sankey,
(104,000 square kilometers) the USGS geologist, who
since September. But au- helped lead the study. "But
thorities know from experi- moving into those areas, warmer climate, experts derstorms in southeast a lot of communities are
ence that the biggest risks where they can acciden- say. Australia in recent weeks working to address these is-
will come with repeated tally set fires. Most of the more than have caused debris flows sues," he added. "It's not all
rains over many months or More than 60% of the wa- 25,000 square miles (64,000 and fish kills in some rivers, doom and gloom because
years while the damaged ter supply for the world's square kilometers) that though fires continue to there are a lot of opportu-
watersheds, or catchment 100 largest cities originates have burned in Victoria burn. nities to reduce risks."
areas, recover. in fire-prone watersheds and New South Wales have "You potentially get this Denver Water, which
And because of the size — and countless smaller been forest, including rain- feedback cycle," where serves 1.4 million custom-
and intensity of the fires, communities also rely on forests, according to scien- vegetation can't recolo- ers, discovered "the high
the potential impacts are surface water in vulnerable tists in New South Wales and nize an area, which intensi- cost of being reactive" af-
not clear yet. areas, researchers say. the Victorian government. fies erosion of any remain- ter ash and sediment runoff
"The forest area burned in When rain does fall, it can Some believe that high ing soil, said Joel Sankey, from two large, high-inten-
Australia within a single fire be intense, dumping a lot temperatures, drought and research geologist for the sity fires, in 1996 and 2002,
season is just staggering," of water in a short period more frequent fires may U.S. Geological Survey clogged a reservoir that
said Stefan Doerr, a profes- of time, which can quickly make it impossible for some The role of climate change handles 80% of the water
sor at Swansea University in erode denuded slopes and areas to be fully restored. is often difficult to pin for its 1.4 million customers,
England who studies the ef- wash huge volumes of ash, Very hot fires burn organic down in specific wildfires, said Christina Burri, a water-
fects of forest fires on sedi- sediment and debris into matter and topsoil needed said Gary Sheridan, a re- shed scientist for the utility.
ment and ash runoff. "We crucial waterways and res- for trees and other vegeta- searcher at the University It spent about $28 million to
haven't seen anything like ervoirs. Besides reducing tion to regenerate, leaving of Melbourne. But he said recover, mostly to dredge 1
it in recorded history." the amount of water avail- nothing to absorb water. the drying effects of wild- million cubic yards (765,555
The situation in Australia il- able, the runoff also can in- The heat also can seal and fire — combined with hot- cubic meters) of sediment
lustrates a growing global troduce pollutants, as well harden the ground, caus- ter weather and less rainfall from the reservoir.
concern: Forests, grass- as nutrients that create al- ing water to run off quickly, in much of Australia, even Since then, the utility has
lands and other areas that gae blooms. carrying everything in its as more rain falls in the spent tens of millions more
supply drinking water to What's more, the area that path. northern part of the coun- to protect the forests, part-
hundreds of millions of peo- burns each year in many That in turn can clog try — mean that "we should nering with the U.S. Forest
ple are increasingly vulner- forest ecosystems has in- streams, killing fish, plants expect more fires." Service and others to pro-
But climate change has af- tect the watershed and
fected areas such as north- proactively battle future
ern Canada and Alaska, fires, including by clearing
where average annual some trees and controlling
temperatures have risen vegetation in populated
by almost 4 degrees (2.2 areas. Utilities also can treat
degrees Celsius) since the slopes with wood chips and
1960s, compared to about other cover and install bar-
1 degree (0.55 degrees riers to slow ash runoff. They
Celsius) farther south. As purposely burn vegetation
a result, the forested area when fire danger is low to
burned annually has more get rid of undergrowth.q