Introduction to Water – Agriculture and Industry
0 Comments


>>So today we are going to look at using water
in agriculture and in industry. Irrigation offers an enormous boost to agriculture as
about 25% of all harvested lands worldwide are using irrigation. And that may not seem
like a lot to you, but in India alone the irrigated land represents about 66 million
acres. That acreage represents an awful lot of grains that provide the primary source
of food calories for millions of Indians. The boom of irrigation worldwide happened
in the latter half of the 20th century, from the 1960s onward. Irrigation was a great thing
at first and happened in one of two ways. Dams were built to store the water from a
stream or rainfall, and canals or pipes were sent from the reservoirs out to farms or wells
were drilled into the vast reservoir of groundwater beneath the surface. This water was then piped
into sprinkler or drip irrigation systems to water the fields. All of this was a wonderful
thing and many more lands were planted and harvested than ever before. But the gains
were not without problems. Dams have ecological consequences, disrupting fisheries and aquatic
life downstream. They also increase the evaporation of water with the reservoir’s high surface
area, and so much of the water stored up gets lost to the atmosphere. A second problem is
that irrigation increases the salinity of the soil. As water trickles down from steep
slopes or is pumped up from the ground, it invariably carries salts and minerals with
it from the soil from which it came. And as more and more water is used and/or evaporated,
what is left on the soil is salt, more and more concentrated as more irrigation water
is applied. Eventually the soil becomes too salty for many plants. In Pakistan alone millions
of acres have been poisoned by high salinity and overall farm yield is down 30% from historic
high levels. Rainwater, on the other hand, is not salty. So rain fed agriculture will
not result in salty soils. A third problem is one that we are very familiar with here
in Oklahoma. Dropping water level in the groundwater aquifer. The Ogallala Aquifer is a vast, shallow
aquifer located beneath the Great Plains in the U.S. It’s one of the world’s largest aquifers,
as it underlies and area of approximately 174,000 square miles in portions of 8 states.
In some places, due to extensive irrigation pumping, the water level is dropping more
than 5 feet per year. And so irrigation may not be sustainable. It may be yet another
example of how we have fooled ourselves into thinking that freshwater is unlimited. In
fact, it is not. Industry is another big user of water. In some countries like the U.S.,
industry is our biggest user of water, using about 60%. Sometimes the quality of this water
is left unchanged, such as when water is used for cooling. But, before we consider quality,
let’s talk about quantity. In terms of quantity, industries are very different in their uses
of water. 10 gallons of water is needed to refine petroleum into 1 gallon of gasoline.
25 gallons of water is needed to make just over 2 pounds of steel. But perhaps the biggest
user is the pulp and paper industry. 86 gallons of water is needed to make just over 2 pounds
of paper. So, when we save paper, we’re not only saving a tree, but also lots of water.
Coca-Cola, like many industries, is starting to track its water use in order to look for
ways to reuse or reclaim water. Coke claims that for every liter of beverage it produces,
it needs 1 liter for the drink itself and 1.43 liters for manufacturing, cleaning, and
processing. Globally it uses enough water in a single day to provide all the water needed
for a metropolitan area the size of Oklahoma City. But Coke has a big goal. Its CEO says
that by the year 2020 Coke will become the first major global corporation to become water
neutral. That is, it will have found a way to reuse its processing water continuously.
That would be a very large step. Regarding water quality, water pollution from industry
can range from heavy metals to highly toxic compounds that are not only poisonous but
also flammable. The Cuyahoga River in Northeastern Ohio actually caught fire at least 13 times
in the 1950s and 60s. The largest river fire in 1952 caused over a million dollars’ worth
in damage to boats and a riverfront office building. Fires erupted on the river several
times between that fire in June 22nd in 1969 when river fire that day captured the attention
of TIME Magazine, which described the Cuyahoga as the river that oozes rather than flows,
and in which a person does not drown but decays. This fire was one of the incidents that helped
spawn the environmental movement in the U.S. and resulted in the Clean Water Act of 1972.
This legislation requires industries or anything that discharges used water from a pipe to
make sure the water is clean to certain minimal standards, especially regarding metals and
the most dangerous toxic compounds. Water pollution is coming out of a pipe is called
a point source and because of this legislation, many of our polluted rivers and streams have
become much cleaner over the past 40 years. To summarize, we enjoy many of the benefits
that water provides us via agriculture and industry, but there is always a price to pay
for this water use, both in terms of creating potential water shortages and in resulting
in water pollution that affects both people and wildlife living downstream.

Leave a Reply

Your email address will not be published. Required fields are marked *