There is no
shortage of water. Amounts available vary regionally and change
over time as precipitation amounts vary. Demand also changes with
increases in population and economic development. Crude estimates
indicate water use per person is 15 liters in undeveloped countries
and approximately 900 liters in developed countries. Throughout
history humans have developed remarkable techniques and technologies
to deal with these issues. Few of these attempted to reduce demand,
most worked to increase supply.
went to great lengths. The extent of the Roman Empire is delineated
by the construction of aqueducts and lead mines developed to produce
pipes to carry their water.
considered important turning points in human development, are technological
controls over weather. Fire, housing and clothing created microclimates
and the ability to live in more extreme conditions. Irrigation was
first introduced in the Fertile Crescent (Figure1) driven by a climate
change. A region that produced crops gradually became drier with
the onset of a warm period called the Holocene Optimum. Besides
the decrease in precipitation there is, at least initially, an increase
Figure 1: The
Fertile Crescent. Source
is to stabilize supply so that plants get the moisture they need
to suit their growth pattern. The contradiction is that as the supply
decreases the demand increases.
One list of
the top 20 weather disasters of the 20th century illustrates the
contradiction. It was dominated by two extremes, droughts and flooding.
Samuel Taylor Coleridge wrote to the contradictions in the Ancient
And all the boards did shrink;
Water, water, everywhere,
Nor any drop to drink.
problem for those who claim there is water shortage or that supply
is threatened. It’s estimated there’s enough in Lake Superior
for total US demand for a year. Compare this with the volume in
the oceans, but that’s the Mariners contradiction. Many suggest
the oceans have an almost unlimited supply, but this raises the
second issue with supply, namely quality. Plants and animals require
a certain quality of water, few more demanding than humans. Before
we can use ocean water we have to remove the salt. Our tongues are
a sensor to protect us from ingesting too much salt with an ability
to detect 200 parts per million (ppm), anything above that level
is increasingly dangerous. Average salt content in seawater is 34,000
of the Titanic disaster was the shift to desalination plants on
ocean going vessels. The Titanic carried massive volumes of freshwater
because large volumes of water are a measure of luxury. When the
buoyancy tanks designed to keep the ship afloat were flooded it
added dangerously to the onboard water volumes. Desalination requires
energy to remove the salt. Surplus heat from the engines, usually
vented through the funnels, is readily available.