Desalination

Sydney, Australia desalination plant

Source: http://www.puroserve.com/blog/1-7-billion-desalination-plant-opens-in-sydney/

A longstanding dream of water users in arid areas close to the ocean and other salt water bodies has been the easy and cheap desalination of salty water. Desalination is possible by the ancient process of distillation and capture of the salt free steam for condensation, but that process is energy intensive and thus only useful when small amounts of water are needed or energy is really cheap. A technology called flash distillation has allowed energy requirements to be lessened somewhat. A quite different technique called reverse osmosis uses special filters and pressure differentials to desalinate water, a common technique for small plants but also used in large ones. It is claimed to use less energy than flash distillation. Both flash distillation and reverse osmosis require expensive facilities. The Sydney plant shown above cost A$1.7 billion (Puroserve).


Saudi Arabia is the largest user of desalinized water, and nearly 3/4 of the water consumed in Saudi Arabia is desalinated, using a little of its ample supplies of petroleum and natural gas to power flash distillation facilities.  Some of the distilled water is also used for agricultural irrigation in the extremely arid portions of the theocratic kingdom. Even oil rich Saudi Arabia is now looking for other energy sources to desalinate water and has contracted for a solar powered plant, sunshine being abundant in the Saudi desert. Most Saudi plants are close to the coast, but a few also operate in the interior using salty ground water.

The city of Sydney in Australia recently brought a large desalinization plant online, a reverse osmosis facility capable of meeting about 15 per cent of the city's water demand. The plant was built and is operated by the Paris based Veolia corporation (formerly Vivendi Environnement, having been spun off from Vivendi. Prior to 1998 Vivendi was known as Compagnie Générale des Eaux (Wikipedia)).  Veolia sells water supply and management services to a number of cities around the world. Growing populations, climate change, and inadequacies of current supplies have prompted several coastal cities in various countries, including Santa Barbara, California, to use one or another type of desalination to meet part of local demand.


A crucial issue in desalination is the disposal of the brine resulting from the process. Much saltier than sea water, the brine can be toxic to marine life when dumped undiluted into the ocean. 


The same processes used to desalinate sea water can also be used to purify sewage and other contaminated water, but the problems of energy demand and waste disposal remain. For the next few decades desalination is likely to remain a small  source for human water supplies, limited to energy rich regions and to places where the price of water is high enough to justify the costs per liter supplied.

International Water Wars? II

Lower Mekong and Tonle Sap in flood, 2001. Source: NASA Earth Observatory

The previous post commented on the conflict between India and Pakistan over the waters of the Indus River. Part of that river arises in the Tibetan highlands controlled by China. China is unlikely to claim much of the flow of the Indus, for in Tibet the headwaters flow through a high altitude region unsuitable for most agriculture and difficult for human settlement, a zone far from the population centers of China. The Mekong which also arises in the southern Chinese highlands is quite a different kind of river, and part of its course is tangential to some of the most fertile and water demanding parts of southern China. In its headwaters area the Mekong is also of some importance for Myanmar (Burma). Along its lower stretches the Mekong is critical for the agriculture and food supply of Cambodia, Laos, Thailand and Viet Nam.

Like many rivers, the Mekong has large seasonal flow variations. The area it passes though is humid but with a monsoonal climate characterized by a distinct dry season in the Northern Hemisphere winter and a wet season in summer. The monsoon rains greatly augment the flow and lead to the annual flooding of Tonle Sap, a very large seasonal lake in Cambodia shown as the dark patch surrounded by green in the  late summer view from space above (courtesy of the NASA Earth Observatory). If it were solely dependent on rainfall in its lower stretches, the Mekong would diminish to a trickle in April and May. Water from snow and glacial melt in the highlands helps to regulate the flow and to keep the river continually navigable for small craft over much of its length as well as to allow for irrigation during the dry season in the tropical lowlands. The annual flooding of Tonle Sap is a major source of food for Cambodia, one of Asia's poorest countries as it allows large fish harvests.

Over the past several years the governments of the lower Mekong countries have observed diminished flow and contend that China is diverting waters for consumptive use. They are observing the construction of large dams in China, including one that will be the highest in the world when it is complete, that will allow China to generate hydroelectric power but also to regulate the flow of the river and possibly to construct works for diversion of the river waters for Chinese urban, industrial, and especially agricultural uses. China did not sign The Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin, an agreement between the four downstream Southeast Asian nations to cooperate in the development of the river. Combined with the projected impacts of climate change and periodic drought Chinese actions could lead to serious problems in the lower Mekong and to direct conflict between China and its smaller neighbors. China denies the claims by the downstream countries, but long-term diminution of the flow may make that denial difficult to accept.

The potentials for conflict over the Mekong are quite different from conflict over the Indus, especially as six countries are involved, but as publications over the past winter (dry season) have illustrated, the possibility is real and potentially dangerous.

International Water Wars?

Indus Valley, Source: NASA Earth Observatory

A potential for water war between India and Pakistan has long been feared by outside observers. An article in today's right-wing Washington Post suggests that possibility is growing greater. The partition of the Raj in the waning hours of British control creating the predominantly Muslim Pakistan and the mostly Hindu India (though India also has a huge Muslim population making it one of the largest Muslim nations) is usually discussed in religious terms. In the bloody aftermath of the partition, Kashmir with a largely Muslim population, remained a major point of contention between the two mostly unfriendly states with Hindu India controlling the crucial eastern section. There have been almost ceaseless and frequently bloody confrontations between Hindus and Muslims and between India and Pakistan, with China later added to the toxic mix, but more frequently than not, the conflict has been discussed in religious and political terms.

In fact the conflict is also over water, for India and China control the crucial headwaters where the Indus River gets the bulk of its flow from melting snowfall and glaciers in the Himalaya. The Indus is a classic example of what the geographer Edward Ullman many years ago termed an exotic river, a stream that after gathering significant flow in a humid zone passes for much of its length through arid areas where rates of evaporation exceed rainfall and little if any water is added to the flow. In the arid zone the river becomes the major, if not the only, source of water and allows human occupation.

One of the oldest areas of agriculture and urban settlement on earth, the Indus Valley, now largely contained within Pakistan, has an almost total dependence on the flow of the Indus. The larger towns and cities use river water for urban and industrial purposes, and agriculture would be impossible were not for withdrawals of Indus water. The critical headwaters, most of the primary sources of the Indus's flow, are controlled by India (and to a much smaller extent by China). India has the ability, and the facilities, to cut off the flow into Pakistan. There is ample demand for the water within India, for its western portions are nearly as dry as most of Pakistan.

A water blockade with most or all of the flows cut off by India would in very short order lead to a collapse of agriculture in Pakistan and intense privation. It could also lead to open warfare between the nuclear armed states. More on this in later postings.

Water Law and Water Rights

Water rights are among the more complicated issues in civil (as opposed to criminal) law in the United States as well as in in many other countries divided between humid and arid zones and in all countries where groundwater is a major source of drinking, agricultural, or industrial water. As I am not a lawyer, I cannot pretend to understand all of the legal ramifications, but water law and the rights to the use of water which the law establishes are crucial matters in national and especially in state and local politics in the United States and many other countries, including the larger English-speaking countries Australia and Canada.

The rights to use water in the western United States are appropriative and relate to the actual use of the water and the length of time that use has been ongoing. Large areas of land west of the 100th Meridian (pace John Wesley Powell, Wallace Stegner, and Walter Prescott Webb) are essentially useless, for no perennial streams cross them and the rainfall is inadequate for crops, and in some instances even for occasional grazing. Only with access to water is the land useful, and governance of that water has been a key theme in the development of states of the western Great Plains and in the intermontane west. As a general rule, the first users to claim water from a stream had long term rights to the use of that water. Under this appropriative doctrine common in states of the western United States, water rights continue to be granted until rights to all of the water in a stream have been granted. Those rights presuppose the actual consumption of the water so that it is not returned to the stream. Even landowners next to a river or smaller stream may have no rights to use it if all of the water has been appropriated, a situation quite different from that in eastern states where riparian rights prevail and anyone owning land along a stream has rights to the use of the water in the stream. In humid areas the use is assumed generally not to be consumptive, and water used is returned to the stream so the downstream flow is undiminished. Of course, the situation in reality is never quite as simple as the law might suggest, and disputes over water rights are common on the dockets of the Federal courts and those of civil courts in the various states.

New Mexico provides a good example of the complexities of water law in a western state, one where appropriative rights are paramount. Water rights are a crucial matter when agricultural land is sold, and there is fierce competition for available water supplies by urban areas. The election for a new governor in November has brought water issues to the fore in a state where drought and population expansion have increased water demands as supply is diminishing. The almost always fascinating blog from Aqua Doc has a good piece on this issue.

Some New Publications on Water Issues

While I have followed the literature on water resources in a more than casual way for a very long time, preparing to lead the water course in the autumn has led me to be attentive to new and especially to popular material (things not written for water specialists) on the subject. There is a rapidly spreading public awareness of how important water resource issues are in the 21st century, and numerous publications have followed from that interest. From time to time I plan to comment on titles that come to my attention, books and articles likely to be of interest to those who enroll in the courses.

Yesterday I received the 22-28th May issue of the Economist magazine, and it includes a special report on water issues "For Want of a Drink." Although I have not yet had time to read the section carefully, a scan reading suggests that it is a good overview of the topic written from the rightist, corporate-friendly perspective of that business and news magazine. While the magazine, like all publications, has biases, the Economist's biases usually do not interfere greatly with the careful collection and analysis of information for which the magazine is rightly valued.

Peter Gleick of the Pacific Institute wrote the recently published Bottled and Sold: The Story Behind Our Obsession With Bottled Water which has been widely and for the most part very positively reviewed. Last week, the NPR Programme "Fresh Air" featured an interview "War On Tap: America's Obsession With Bottled Water."  Ms. Gross is not my ideal interviewer, but the interview is worth a listen. While I have not yet purchased or read the book, Gleick's past works suggest it is worth buying and reading. (Noted added 3 June: The Diane Ream show from WAMU in Washington, DC and carried by public radio in many other markets also had an interesting interview with Gleick which aired on 27 May. The link is to a recording of the interview).

A couple of weeks ago I bought a copy of Water: The Epic Struggle for Wealth, Power and Civilization by Steven Solomon. Great minds think alike, I guess, for my rough draft outline of ideas to present in the first water class session parallels Solomon's book closely. Needless to say he covers far more ground in over 500 pages than I can hope to cover in a 90 minute class session, so the book is strongly recommended to anyone fascinated by the links between control of water and more general issues of human civilization.

I am working on a bibliography of materials for use with the three courses, and each of the titles listed above are likely to be on that list under the heading of worthwhile popular works.

Introduction

Beginning in the Autumn 2010 term, I am leading three related courses at the Tallwood facility of OLLI at George Mason University: Autumn 2010 World Water Supplies -  the Coming Crisis; Spring 2011 World Food Supply - Famine on the Horizon?; and Spring 2012 World Population Dynamics and Growth (that last title may change as the proposed course is rather far into the future). This blog is intended to support those courses with comments on matters related to the courses, responses to questions and comments raised in class sessions, recommended readings, links to useful supplementary materials, and anything else that seems worth pursuing in the informal context of a blog.