The increasing frequency of major flooding
in parts of the United States coupled with dam failures such as the breached
Edenville and Sanford dams in Michigan should serve as a warning on the
vulnerability of our infrastructure during extreme weather, according to Mark
Anderson, an instructor at South
Dakota School of Mines & Technology’s Department of Civil and Environmental
Engineering.
“The nation’s water infrastructure is in need of engineering
attention,” says Anderson, who previously served as the director of the United States
Geological Survey (USGS) Dakota Water Science Center in Rapid City, and has
spent his career working on water issues.
These challenges highlight the need for scientists and
engineers trained at institutions like South Dakota Mines. Civil engineers can
lead the way in innovative renovations to existing infrastructure and designs
for new dams, bridges and roads that are more resilient to withstand a changing
climate. Environmental engineers can help design new infrastructure that works
in harmony with the natural world. Scientists like meteorologists and
climatologists can lend to the understanding of what is coming and what society
will need to do to prepare.
The United States Army Corps of
Engineers National
Inventory of Dams shows 15,491
are classified as “high” hazard dams with another 11,333 that are “significant”
hazards. On the high hazard list was the Edenville
Dam that failed catastrophically on May 20, 2020. A 2011 report by
the Congressional Research Service titled “The Bureau of
Reclamation’s Aging Infrastructure” points out that most Reclamations dams
have an average age of over 50 years. It is now 10 years later.
Climate change adds another level
of complexity to the challenge of aging water infrastructure, Anderson says. “Many
of the dams weren’t built or designed to cope with increased weather
variability now being documented,” says Anderson. An article in Science
magazine, “Stationarity
Is Dead: Whither Water Management?” points out that greater rainfall and
streamflow means the criteria engineers used - based mainly on historical
observations - to design thousands of dams around the United States no longer
holds true. “We need
scientists and engineers to help us migrate to the next better design system,”
says Anderson.
When dams fail, major loss of life
can occur. The Association of State Dam Safety Officials have a number of case
studies on their Lessons Learned
page. Anderson points to the 2019 collapse of the Spenser Dam on the Niobrara
River in Nebraska and the 2017 near collapse of the Orville
Dam in California which forced the evacuation of about 200,000 people, as
two examples that should serve as another warning today. Repair of the Orville
Dam is now expected to exceed
$1.1 billion and that is just one dam among thousands that need attention.
“We are on the cusp of a major
recognition that our dams need to be retrofitted, redesigned, reconstructed and
in some cases, completely removed when modern environmental concerns prevail,”
says Anderson. Fish passage and restoration of the salmon habitat tilted the
balance for removal of the Elwha and Glines Canyon Dams in Washington State and
the Marmot Dam in Oregon. Scientists and engineers led the schedule of deconstruction,
with data that predicted sediment release and salmon repatriation. Anderson says
the Bureau of Reclamation and other regulatory agencies do a fantastic job with
the resources they have. But he adds that “these are complex problems that will
take resources and a lot of science and engineering expertise.”
Both the Missouri and Mississippi River
Basins saw major flooding in 2019. It was the wettest year on record in some
parts of these watersheds.
One report shows record river levels were
reached in locations across six states. In many areas, the ground
remains saturated as the 2020 spring and summer wet season approaches.
“Increased rainfall also means that more precipitation is shunted towards
surface and river runoff rather than further soil water storage. This enhances
local flood risk and adds up over a river basin,” says Bill Capehart, Ph.D., who leads the Atmospheric and
Environmental Sciences program at South Dakota Mines.
“Risks to our aging infrastructure are not just limited to
dams,” says Capehart. In 2019, Interstate 90 in eastern South Dakota was closed
for the first time in its history because of water flowing over the driving
surface. “Overall, our national infrastructure is losing resiliency with the existing
climate before factoring in the potential of climate change.” Anderson
adds that ageing and vulnerable infrastructure includes water treatment
and distribution systems across the country. Many of these systems lie in
floodplains or along coastal areas that can be threatened by a changing climate.
A 2017 report by the American Association of Civil Engineers gave our overall national
infrastructure grade a “D+.” The American Road and Transportation Builders Association
also recently reported
that Great Plains states including South Dakota, North Dakota and Iowa had more
than 10% of their bridges listed as structurally deficient. Some of the impacted
bridges are part of the heavily traveled interstate highway system. Capehart
says climate change will bring an increase in extreme events. “On top of this,
lower-intensity ‘nuisance’ events will likewise become more frequent, creating
more instances of damage that are often absorbed by property owners rather than
insurance and large-scale relief programs,” says Capehart.