By Dr. Tim Ball Thursday, November 4, 2010
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.
Some societies 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.
Major advances, 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 in variability.
Figure 1: The Fertile Crescent. Source:
The objective 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 Mariner,
Water, water, everywhere,
And all the boards did shrink;
Water, water, everywhere,
Nor any drop to drink.
It’s the 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 ppm.
One outcome 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.
The energy source is important because it determines the cost of the water. Several systems are operating round the world. They are fuelled by oil, nuclear, and until regulations changed, burning garbage. In the 1980s Japan offered to sell water to Saudi Arabia at a lower cost than desalination even with their oil. Interestingly, Saudi Arabia turned the offer down because they didn’t want to depend on a foreign nation for a primary resource. The Saudi’s recently signed a contract with Japan to facilitate water desalination projects.
Solar energy is not a viable alternate energy because it’s intermittent and requires almost 100% backup. However, like some alternate energies it has specialized applications. The Ancient Mariner’s problem of no drinking water faced pilots who ditched in the ocean during WWII. A simple device was produced to provide adequate water to prevent dehydration. It was an inflatable ring like a child’s paddling pool, but with an inflatable tripod holding up clear plastic panels. Sunlight passed through the plastic, raised the temperature and increased the rate of evaporation. When salt water evaporates it does so as freshwater. This means freshwater condenses on the inside of the clear plastic, where it can trickle down to a collecting channel. Similar vast floating devices could cover stretches of ocean, producing freshwater that is then pumped ashore with energy from solar power. Intermittent energy supply is not a problem because the water is easily stored on land.
Diversion of water through elaborate canals and pipes are the most common systems used by people throughout history. The water system at Machu Picchu, the ancient Inca city high in the Andes, is little known, but one of the most amazing pieces of engineering in a city of engineering marvels. They have also used some amazing ways of tapping into supplies. For example, a series of shafts go down to the water table where they connect a tunnel that taps the groundwater. They are called Qanats and are found from China to the Middle East, and Galeria in Mexico and Central America (Figure 2).
Figure 2: Cross-section through a Qanat. Source:
Some Qanats are centuries old and many are being brought back into use or expanded.
Other ideas include using oil tankers to draw fresh water directly from the ocean surface off the coast of Brazil. The volume of flow in the Amazon is so great that there is fresh water up to 200 km offshore.
People living in naturally dry areas usually drive other ideas proposed for obtaining more water. A major part of the population shift in the US is from the wet east to the dry west driven by Horace Greeley’s suggestion to go west young man. Few regions have extended their tentacles further to tap water supply than Southern California. It’s not surprising they were a region, followed by Saudi Arabia and Australia, to investigate towing icebergs from Antarctica. The idea is to carve off pieces of shelf ice, the source of large tabular icebergs. These frequently break away as the glacier advances into the ocean. Estimates are that 50 percent of the glacier would melt in passage. At its destination it is beached, surrounded with a plastic curtain to contain the melt-water that is then pumped ashore.
There are no water shortages. There are regions of deficit and surplus and these amounts change over time. Water is not lost. If taken out of the system in one place it is ultimately returned. Israel is one country that has assessed its water supply and done more with technology to maximize use. In most other regions governments have taken pride in providing water without a thought to the real value. It is probably the ultimate entitlement.
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Dr. Ball can be reached at: Letters@canadafreepress.com
- How Desalinization Works (treehugger.com)
- Turning Water Into… Water – Blog Action Day 2010 (gcaptain.com)