Chapter 13 – Living in the Environment/ 12th ed
I. Introduction – the Prophecy:
Our liquid planet glows like a
soft blue sapphire in the hard-edged
darkness of space. There is nothing
else like it in the solar system.
It is because of water.
John Todd
We live in a water world. Water – mostly salt water - covers 71% of the planet’s surface. It is the basis of life, all organisms are made up mostly of water – a tree is about 60% water by weight and most animals are about 50-65% water. There are no substitutes for most of the uses of water resources, not only as drinkable water, but also as a supplier of food and in sculpting the earth’s surface, moderating climate and diluting pollutants.
Despite the fact that water is the lifeblood of the biosphere, it is also one of our most poorly managed natural resources. We waste it and pollute it, we also charge too little for making it available, thus encouraging still greater waste and pollution.
Only a tiny fraction of the planet’s abundant water supply is available to human use as fresh water. About 97.4% by volume is found in the oceans and is too salty for drinking, irrigation or industry (except as a coolant)[1]. Most of the remaining 2.6% that is fresh water is locked up in ice caps or glaciers or is in groundwater too deep or salty to be used. Thus, only about 0.014% of the earth’s total volume of water is easily available to us as soil moisture, usable groundwater, water vapor, and lakes and streams.
Fortunately, the available fresh water amounts to a generous supply. About 20% of all water running to the sea each year is in rivers too remote to supply cities and farming regions. Downpours of rain that cannot be collected make up another 50% of the total global runoff. This leaves about 30% of the total global runoff for human use.
This available water is continuously collected, purified, recycled, and distributed by the solar-powered hydrologic cycle[2] as long as we do not overload it with slowly degradable and nondegradable wastes or withdraw water from underground supplies faster than it can replenish. Unfortunately, we are doing both. Also, global warming is projected to alter the global hydrological cycle. A warmer atmosphere will increase global rates of evaporation, shift precipitation patterns, and disrupt water supplies in unpredictable ways. Some areas will get more precipitation and some less. River flows will change. Monsoons and hurricanes are likely to intensify, and the average sea level will rise from thermal expansion of the oceans and partial melting of ice caps and mountain glaciers.
Nature’s water delivery does not match up with the distribution of much of the world’s population. Differences in average annual precipitation divide the world’s countries and people into water haves and have-nots. For example, Canada with only 0.5% of the world’s population, has 20% of the world’s fresh water[3], whereas China with 21% of the world’s population has only 7% of the supply. Asia, in general, with 61% of the world’s people, has only 36% of the earth’s reliable annual runoff, and South America, with 26% of the earth’s reliable runoff, has only 8% of the world’s people. About 60% of South America’s runoff flows through the Amazon River in remote areas where few people live[4]. Two countries share almost 150 of the world’s 214 major river systems (57 of them in Africa), and another 50 are shared by 3 to 10 countries. Some 40% of the world’s population already clashes over water.
Since 1990, global water use has increased about ninefold and per capita use has quadrupled, with irrigation accounting for the largest increase in water use. As a result, humans now withdraw about 35% of the world’s reliable runoff. At least another 20% of this runoff is left in streams to transport goods by boats, dilute pollution, and sustain fisheries. Thus, we are directly or indirectly using more than half of the world’s reliable runoff. Because of increased population growth (between 2000 and 2054, the world’s population is expected to increase by about 3 billion people) and economic development, global withdraw rates of surface water are projected to at least double in the next two decades and exceed the reliable surface runoff in a growing number of areas.
As population, irrigation, and industrialization increase[5], water shortages in already water-short regions will intensify and heighten tensions between and within countries. As water becomes scarcer, access to water resources will be a major factor in determining the economic, environmental, and military security of a growing number of countries. According to Lester Brown and Christopher Flavin from the Worldwatch Institute, “The spreading scarcity of water may be the most underestimated resource issue facing the world as it enters the new millennium.”
In fact, a world without drinkable water, with its supplies contaminated and polluted and people dying from starvation and diseases is a prophecy widely depicted in movies and books[6]. It is up to our generation to make this prophecy remain as a science fiction story or allow it to become a devastating reality.
II. The Water Wars - the Middle Eastern situation:
The wars of the next century
will be about water.
Ismail Serageldin,
Vice-president of the World Bank.
According to water expert Malin Falkenmark, there are four causes of water scarcity: (1) a dry climate, (2) a drought (a period of 21 days or longer in which precipitation is at least 70% lower and evaporation is higher than normal), (3) desiccation (drying of the soil because of such activities as deforestation and overgrazing by livestock)[7], and (4) water stress (low per capita availability of water caused by increasing numbers of people relying on limited levels of runoff). A country is said to be water stressed when the volume of its reliable runoff per person drops to below about 1,700 cubic meters (60,000 cubic feet).
Data from the United Nations and the World Bank shows that about 500 million people live in 34 Asian, African and Middle Eastern countries suffering from water stress, and this could increase to almost 3 billion people in 50 countries by 2025. Water shortages in Africa are expected to be especially acute because 67% of its land is dry (40%) or desert (27%), and its population is expected to increase from 800 million to 1.3 billion between 2000 and 2025.
All but 2 of the world’s 34 water-stressed countries must import about one-fourth of the world’s total grain exports to supplement their food production. As population grows and water scarcity increases, such grain exports are expected to increase. This could heighten competition for the world’s grain exports between countries such as China and other developing countries in Asia, Africa and the Middle East, raise grain prices, and increase hunger and malnutrition in developing countries that cannot afford to pay higher prices for grains.
Evidence of water stress is seen in damming and draining rivers to supply water for irrigation and cities and dropping water tables in some of the world’s major food-producing areas. According to a 1999 report by the World Commission on Water in the 21st Century (funded by the United Nations and the World Bank), half of the world’s major rivers are going to dry part of the year or are seriously polluted.
This situation leads to another prophecy -- the next global war will be over water! According to United Nations Secretary-General Kofi Annan: “fierce competition for fresh water may well become a source of conflict and wars in the future.”
This tension is especially felt in the Middle East, whose countries have some of the highest population growth rates in the world. Because of the dry climate, food production depends heavily on irrigation. Existing conflicts between countries in this region over access to water may soon overshadow both long-standing religion and ethnic clashes and attempts to take over valuable oil supplies. In fact, water has been called “the oil of the 21st century”.
In the Middle East, most of the water comes from three shared river basins: the Nile, Jordan and the Tigris-Euphrates.
In the Niles Basin, Ethiopia controls the headwaters that feed 86% of this river’s flow, and it plans to divert more of this water; so does Sudan. This could reduce the amount of water available to water-short Egypt, whose terrain is desert except for a green area of irrigated cropland running down its middle along the Nile and its delta. Between 2000 and 2025, Egypt’s population is expected to increase from 67 million to 97 million, greatly increasing the demand for already scarce water. Egypt’s option will be: (1) go to war with Ethiopia and Sudan, (2) cut population growth, (3) improve irrigation efficiency, (4) spend $2 billion to build the world’s longest concrete canal and pump water out of Lake Nasser (the reservoir created from the Nile by the Aswan High Dam)[8] and create more irrigated farmlands in the middle of the desert, (5) import more grain to reduce the need for irrigation water, (6) work out water-sharing agreements with other countries, or (7) suffer the harsh human and economic consequences.
In fact, shortages of water create millions of environmental refugees. According to the United Nations, in 1998 about 25 million people had to flee their homes because of water shortages, pollution and flooding in their river basins. By 2025, the number of such environmental refugees could quadruple. In water-short rural areas in developing countries, many women and children must walk long distances each day, carrying heavy jars or cans, to get a meager and sometimes contaminated supply of water.
The Jordan Basin is by far the most water-short region, with a fierce competition for its water between Jordan, Syria, Palestine (Gaza and the West Bank), and Israel. This is one more component of the tensions between Jewish and Muslims (especially Palestinians). The combined populations of these already water-short countries are projected to increase from 31 million to 51 million between 2000 and 2025. Syria plans to build dams and withdraw more water from the Jordan River, decreasing the downstream water supply for Jordan and Israel. Israel warns that it will consider destroying the largest dam that Syria plant to build.
In the Tigris-Euphrates Basin, Turkey - located in the headwaters -, controls how much water flows downstream to Syria and Iraq before emptying into the Persian Gulf. Turkey is building 24 dams along the upper Tigris and Euphrates rivers to (1) generate huge quantities of electricity, (2) irrigate a large area of land, (3) boost the region’s income fivefold, and (4) generate about 3.5 million jobs for its 65 million people. If completed, these dams will reduce the flow of water downstream to Syria and Iraq by up to 35% in normal years and much more in dry years. Syria also plans to build a large dam along the Euphrates River to divert water arriving from Turkey, which will leave little water for Iraq and possibly lead to a war between Syria and Iraq.
Clearly, water distribution will be a key issue in any peace talks in the Middle East. Resolving these problems will require a combination of regional cooperation in allocating water supplies, slowed population growth, improved efficiency in water use, and increased water prices to encourage water conservation and improve irrigation efficiency.
III. Increasing the fresh water supply:
It is not until the well runs dry
that we know the worth of water
Benjamin Franklin
There are five ways to increase the supply of fresh water in a particular area:
III.1. Building dams and reservoirs:
The main purpose of dams and large reservoirs is to capture and store runoff and release it as needed for (1) controlling floods, (2) producing hydroelectric power, and (3) supplying water for irrigation and for towns and cities. Reservoirs also provide recreational activities such as swimming, fishing, and boating. Many rivers resemble an elaborate plumbing system, with multiple dams used to control the timing and flow of water, like water from a faucet. The goal of this engineering approach to river management is to capture and use as much of a river’s flow as possible. This has worked, with the world’s dams increasing the annual runoff available for human use by nearly one-third.
However, a series of dams on a river, especially in arid areas, can reduce downstream flow to a trickle and prevent it from reaching the sea as a part of the hydrologic cycle. Major rivers that run dry and do not reach the sea anymore during the dry season include the Colorado River in the United States, the Yellow River in China, the Nile in the Middle East, the Ganges and Indus in South Asia, and the Amu Darya and Syr Darya in five countries that once were part of the Soviet Union. Also, dams and reservoirs impairs the important ecological services that rivers provide[9].
See the example of the Aswan High Dam in Egypt, which was built in the 1960s to provide flood control and irrigation water for the lower Nile basin and electricity for Cairo and other parts of Egypt. In fact, it has supplied about one-third of Egypt’s electrical power. Other benefits have been the storage of water for irrigation, which saved Egypt’s rice and cotton crops during severe droughts in the 1970s and 1980s and helped avert massive famines; and it has also increased food production by allowing year-round irrigation of nearly 3.3 million hectares (8.2 million acres) of land in the lower Nile basin.
However, when Lake Nasser was flooded to construct the dam, 125,000 people were uprooted. The dam has also produced other harmful ecological and economic effects, including:
- Ending the yearly flooding that for thousands of years had fertilized the Nile’s floodplain with silt, most of it washed down from the Ethiopian highlands. Now the river’s silt accumulates behind the dam, filling Lake Nasser and eventually making the dam useless;
- Necessitating the use of commercial fertilizer on cropland in the Nile Delta basin at an annual cost of more than $100 million to make up for plant nutrients once available at no cost. The country’s new fertilizer plants use up much of the electrical power produced by the dam;
- Increasing salinization because there is no natural annual flooding to flush salts from the irrigated soil. This has offset about three-fourths of the gain in food production from new land irrigated by water from the reservoir;
- Eliminating 94% of Nile water that once reached the Mediterranean Sea each year and upsetting the ecology of waters near the mouth of the Nile;
- Eliminating the annual sediment discharge where the Nile reaches the sea. This has caused the coastal delta to erode and advance inland and has reduced productivity on large areas of agricultural land;
- Eradicating most of Egypt’s sardine, mackerel, shrimp, and lobster fishing industries because nutrient-rich silt no longer reaches the river’s mouth. This has led to losses of approximately 30,000 jobs, millions of dollars annually, and an important source of protein for the Egyptians. However, a new fishing industry taking bass, catfish, and carp from Lake Nasser has offset some of these losses.
Ideally, in developing a dam or a reservoir the human needs for water should be balanced with preserving a river’s ecological services. However, achieving this goal is difficult because the amount of available and usable water from a river varies with the time of the year, conditions such as drought and higher-than-normal precipitation, pollution loads, habitat needs of aquatic life, and the values people place in wildlife, fisheries, and recreational use of river basins. One approach is to develop computer models to take such factors into account and estimate the minimum amount of water needed to satisfy basic human and ecological needs.
III.2. Transferring surface water:
Tunnels, aqueducts, and underground pipes can transfer stream runoff collected by dams and reservoirs from water-rich areas to water-poor areas. One of the world’s largest watershed transfer projects is the California Water Project. In California, the basic water problem is that 75% of the population lives south of Sacramento but 75% of the state’s rain occurs north of Sacramento.
The California Water Project uses a maze of giant dams, pumps, and aqueducts to transport water from northern California (water-rich) to southern California (heavily populated, and arid and semiarid agricultural regions). The tension between north and south is felt. South demands more water to support cities like San Diego and Los Angeles, and for the agriculture which uses 74% of the water withdraw in California. The north contends that sending more water south would degrade the Sacramento River, threaten fisheries and reduce the flushing action that helps clean San Francisco Bay of pollutants. They also argue that most water sent south is wasted. Pumping more groundwater is not the solution, because this resource is already withdrawn faster than it can replenish in California. The solution would be to improve irrigation efficiency and to allow farmers to sell their legal rights to withdraw certain amounts of water from rivers[10].
Although such transfers have benefits, they also create environmental problems. See the example of the Aral Sea water transfer disaster, which was described by one former Soviet official as “ten times worse than the 1986 Chernobyl nuclear power-plant accident”. The shrinking of the Aral Sea is a result of a large-scale water transfer project in areas of the former Soviet Union with the driest climate in central Asia.
Since 1960, enormous amounts of irrigation water have been diverted from the inland Aral Sea and its two feeder rivers, and since then: the sea’s salinity has tripled, its surface area has shrunk by 54%, its volume has decreased by 75%, its two supply rivers have become mere trickles, and about 36,000 square kilometers (14,000 square miles) of former lake bottom has become human-made desert covered with salt. Within 10-20 years the once enormous Aral Sea may break up into three small brine lakes.
This has affected the fishing industry (24 species of fish have become extinct) and wetlands (reducing populations of birds and mammal species). Also, the salt is blown by the wind into fields and farmers need to use more herbicides, insecticides, fertilizers and irrigation water. The increase in the use of chemicals has contaminated groundwater from which most of the population’s drinking water comes from, and through irrigation these chemicals have been brought up the surface and also contaminated drinking water supplies. In fact, the Aral Sea basin may have one the world’s worst salinization problems, which gets worse because of the positive feedback loop that occurs through irrigation. The extra input of irrigation water increases water use, further shrinks the Aral Sea and increases the salt blowing onto croplands, and adds more salt from irrigation water to the soil.
The conversion of the Aral into a salt desert has deep consequences in the region’s climate because it no longer acts as a thermal buffer, moderating the heat of summer and the extreme cold of the winter. Now, there is less rain, summers are hotter and drier, winters are colder, and the growing season is shorter.
The combination of toxic dust, salt and contaminated water has caused serious problems to the population’s health, which includes abnormal rates of infant mortality, tuberculosis, anemia, respiratory illness, eye diseases, throat cancer, kidney and liver diseases, arthritic diseases, typhoid fever, and hepatitis
Seeking a solution for this problem, the United Nations and the World Bank plan to spend $600 million, between 1999 and 2002, to purify drinking water, upgrade irrigation and drainage systems to improve irrigation efficiency, flush salts from croplands and boost crop productivity, and construct wetlands and artificial lakes to help restore aquatic vegetation, wildlife, and fisheries. However, this project will take decades and can no longer prevent the shrinkage of the Aral Sea into a few brine lakes. Also, in 1994, the presidents of five countries in the Aral Sea basin developed a regional water management plan to address the area’s dire water, ecological, and health problems. This plan acknowledges that the region’s current agricultural practices are unsustainable and confirms that principles of international law should be used to allocate water between the five countries. However, it does not discourage most of these countries from expanding irrigated land to help support their declining economies.
III.3. Tapping groundwater:
Aquifers provide drinking water for at least one-fourth of the world’s population. In Asia more than 1 billion people depend on groundwater for drinking (32% of the drinking water), half of India’s irrigation and 90% of Bangladesh’s drinking water comes from aquifers, 75% of the drinking water in Europe and 29% in Latin America comes from underground, and in the U.S. half of the drinking water (96% in rural areas and 20% in urban areas) and 43% of irrigation water is pumped from aquifers. In Florida, Hawaii, Idaho, Mississipi, Nebraska and New Mexico, more than 90% of the population depends on groundwater for drinking water.
Pumping groundwater from aquifers has several advantages over tapping more erratic flows from streams. First, groundwater can be removed as needed year-round, it is not lost by evaporation, and it is usually less expensive than to develop surface water systems. However, it can also cause several problems, such as: water table lowering[11], aquifer depletion and subsidence (sinking of land when groundwater is withdrawn), intrusion of salt water into aquifers (when fresh water from an aquifer near a coast is withdrawn faster than it is recharged, salt water intrudes into the aquifer and contaminates the drinking water supply of many towns and cities along coastal areas), drawing of chemical contamination in groundwater toward wells, and reduced stream flow because of diminished flows of groundwater into streams.
Groundwater pollution and depletion are serious problems especially because they are hidden from view and because the supply is renewed very slowly. Groundwater is polluted by storage lagoons, septic tanks, landfills, hazardous waste dumps, and deep injection wells and store petrochemicals such as gasoline, oil, organic solvents, pesticides, arsenic, lead and fluoride and hazardous wastes in metal underground tanks that after 20-40 years can corrode and leak. It is also contaminated by people who dump or spill gasoline, oil, and paint thinners and other organic solvents onto the ground.
Because the average recycling time of groundwater is 1,400 years compared to 20 days for river water, once it becomes contaminated it cannot cleanse itself of degradable wastes as flowing surface water does. This is because it flows so slowly (usually less than 0.3 meters or 1 foot per day) that contaminants are not diluted and dispersed effectively, it also has much smaller populations of decomposing bacteria, and its cold temperatures slows down the chemical reactions that decomposes waste. This means that it may take hundreds of thousands of years for contaminated groundwater to cleanse itself of degradable wastes and on a human time scale nondegradable wastes (such as toxic lead, arsenic and fluoride) are there permanently.
One proposed solution to clean-up groundwater pollution would be to pump it to the surface, treat it and return to the aquifer. However, this is extremely costly and time consuming (it would take 50-1,000 years of continuous pumping before all the contamination is forced to the surface). Thus, prevention is the best option and can be accomplished through: monitoring aquifers near landfills and underground tanks, requiring leak detection systems for underground tanks used to store hazardous liquids, banning or more strictly regulating disposal of hazardous wastes in deep injection wells and landfills, and storing hazardous liquids above ground in tanks with systems that can detect and collect leaking liquids.
As said before, groundwater depletion is also a major concern. According to Worldwatch Institute estimates, unsustainable depletion of groundwater is being used to produce about 10% of the world’s annual grain harvest. This example of the tragedy of the commons is expected to increase as irrigated areas are expanded to help feed the 2 billion more people projected to join the world’s population between 2000 and 2028. In addition to limiting future food production, overpumping aquifers is increasing the gap between the rich and the poor in some areas. As water tables drop, farmers must drill deeper wells, buy larger pumps to bring the water to the surface and use more electricity to run the pumps.
Groundwater is being withdrawn faster than it can replenish not only in the United States[12], but in Saudi Arabia, central and northern China, northern and southern India, northern Africa, southern Europe, the Middle East, and parts of Mexico, Thailand, and Pakistan. Portions of Mexico City, Mexico, and Bangkok, Thailand, are sinking as geologic formations compact and subside after groundwater is removed.
Groundwater depletion is difficult to be solved because it reflects a tragedy of the commons situation and, as we discussed in footnote 8, the laws and customs regarding groundwater use allows landowners unlimited water extraction from aquifers underlying their land. Ways to prevent or slow groundwater depletion involve controlling population growth, not planting water-intensive crops such as cotton and sugarcane in dry areas, shifting to or developing crops that need less water and are more resistant to heat stress, and wasting less irrigation water.
III.4. Converting salt water to fresh water (desalinization):
Desalinization is not responsible for a significant part of the solution to the global fresh water shortage problem. About 11,100 desalinization plants in 120 countries (especially in the arid Middle East and parts of North Africa) meets less than 0.15% of the world’s water needs. Desalinization would have to increase 33-fold just to supply 5% of the current world water use.
Desalinization is the process of removing dissolved salts from ocean water or from brackish (slightly salty) groundwater. It separates saline water in two streams: one with a low concentration of dissolved salts (freshwater) and another containing the remaining dissolved salts (concentrate). It can be accomplished through three main methods:
- Thermal distillation, or evaporation:
It is the oldest method. Solar distillation methods have been used since c.49 B.C. by the legions of Julius Cesar for using water in the Mediterranean. It involves heating salt water in a container until it evaporates (and leaves behind salts in solid form) and condenses as fresh water in a separate container. Modern technological advances led to the development of more efficient distillation units using solar energy; however, since these units have small capacities, their utility is restricted.
Internationally, distillation is used extensively to treat full-strength seawater, but it has found limited application in water supply because of the fuel costs involved in converting saltwater to vapor. Indeed, distillation plants having high capacities and using combustible fuels employ various devices to conserve heat. In the most common system, called multistage flash method, a vacuum is applied to reduce the boiling point of water, or a pray or thin film of water is exposed to high heat, causing flash evaporation; the water is flashed repeatedly, yielding fresh distilled water.
The first municipal desalinization plant in the United States -- built in the 1940s in Key West, Fla. -- employed distillation, but the use of membrane filtration is more prevalent in modern U.S. facilities;
- Electrodialysis:
This method uses ion-specific membranes that are arrayed between anodes and cathodes to drive salt ions in controlled migrations to the electrodes, leaving freshwater behind. When salt dissolves in water, it splits into charged particles called ions. Placed in a container with a negative electrode at one end and a positive electrode at the other, the ions are filtered by the membranes as they are attracted towards the electrodes; they become trapped between semipermeable membranes, leaving outside the membranes a supply of desalinated water that can be tapped.
The first large installation using this process began in South Africa in 1958, but its high electrical demand makes it impractical except where such energy is abundant.
- Reverse osmosis:
This is by far the most promising method of desalinization, in which salt water is pumped at high pressure through a thin, semi-permeable, membrane whose pores allow water molecules, but not dissolved salts, to pass through. This method is based on separation rather then on distillation. It is also economically the best approach. Where multi flash distillation costs about $4 per 100 gallons, reverse osmosis costs less than half that amount.
For emergency use, i.e., in lifeboats, various systems are available in addition to solar or fuel-heated distillation devices. One device made of flexible plastic is worn around the waist of the user to employ body heat for evaporation. Another type is an empty hollow sphere of semipermeable material that is lowered into the sea. The water flowing into the spheres is fresh, since the salt is excluded by the membrane that covers the entire sphere and is its guard. One final approach is under development in Hawaii, where different layers of seawater display a large temperature differential. There an Ocean Thermal Energy Conversion plant is being built which will use steam produced by the flash method to produce energy, then condense the steam into freshwater. Three such plants could produce a hundred megawatts of power, as well as supply 30% of Hawaii’s water needs.
Scientists are working to develop new membranes for reverse osmosis that can separate water from salt more efficiently and under less pressure. This could help bring even more down the costs of the process.
Another research conducted by physicist Mark Andelman, president of Worcester, Mass.-based Biosources, at Boston College, is based on the use of nanotubes (tiny tubes). The University is teaming up with the independent inventor Zhifeng Ren to use carbon pipes only a few nanometers (billionths of a meter) across as a fast and energy-efficient means of water desalinization. Key to the work is professor Ren’s discovery of a way to fabricate the tubes as an extremely well aligned nano “forest”.
The nanotubes are electrically charged, and when saltwater runs through them, sodium and chloride ions are electrostatically adsorbed onto the tube surfaces; rapidly removing the charge releases the ions into a waste stream. Because of the nanotubes high electrical conductivity and large surface areas relative to their volume, they are far more efficient in ridding the water of salt than carbon. The research is funded by the Defense Advanced Research Projects Agency, which wants to develop a portable, energy-efficient desalinization unit.
Desalinization can provide fresh water for coastal cities in arid countries, where the cost of getting fresh water by any method is high, such as sparsely populated Saudi Arabia and Israel. However, desalinization may never be cheap enough to be used in conventional irrigation or to meet the world’s demand for fresh water unless affordable solar-powered distillation plants can be developed and someone can figure out what to do with the resulting mountains of salt. These are, in fact, the two major disadvantages of desalinization: it is expensive because it takes large amounts of energy, and it produces large quantities of waste water (brine) containing high levels of salt and other minerals. Dumping the concentrated brine into the ocean near the plants increases the local salt concentration and threats food resources in estuary waters, and dumping it on land could contaminate groundwater and surface water.
III.5. Cloud seeding and towing icebergs:
These are not feasible solutions, but will be discussed for the sake of argument.
For decades several countries, especially the United States, have been experimenting with seeding clouds with tiny particles of chemicals, such as silver iodide, to form water condensation nuclei and produce more rain over dry regions and more snow over mountains. However cloud seeding is not useful in very dry areas, where it is most needed, because rain clouds rarely are available there, and would introduce large amounts of the cloud-seeding chemicals into soil and water systems, possibly harming people, wildlife, and agricultural productivity. Another obstacle to cloud seeding is legal disputes over the ownership of water in clouds. During the 1977 drought in the western U.S., the attorney general of Idaho accused officials in neighboring Washington of “cloud rustling” and threatened to file suit in federal court.
There also have been proposals to tow massive icebergs to arid coastal areas (such as Saudi Arabia and southern California) and then to pump the fresh water from the melting bergs ashore. However, the technology for doing this is not available and the costs may be too high, especially for water-short developing countries, not to mention the environmental disruption of such as unusual operation.
IV. Improving water use efficiency – the Blue Revolution of water conservation:
It is a hard truth to swallow
but nature does not care if we
live or die. We cannot survive
without the oceans, for example,
but they can do just fine without us.
Roger Rosenblatt
According to Mohamed El-Ashry, from the World Resources Institute, sixty five to seventy percent of the water people use throughout the world is lost through evaporation, leaks and other losses.
Methods for achieving more sustainable use of the earth’s water resources are: (1) not depleting aquifers, (2) preserving ecological health of aquatic systems, (3) preserving water quality, (4) using integrated watershed management[13], (5) establishing agreements among regions and countries sharing surface water resources (like the Aral Sea Agreement discussed above), (6) having outside party mediation of water disputes between nations, (7) marketing water rights, (8) wasting less water, (9) decreasing government subsidies for supplying water and increasing government subsidies for reducing water waste, and (10) slowing population growth.
The challenge in developing such a blue revolution is to implement a mix of strategies built around: irrigating crops more efficiently, using water-saving technologies in industries and homes, and improving and integrating management of water basins and groundwater supplies. Accomplishing such a revolution in water use will be difficult and controversial. However, water experts contend that not developing such strategies will eventually lead to economic and health problems, increased environmental degradation and loss of biodiversity, heightened tensions and perhaps armed conflicts over water supplies, larger number of environmental refugees, and threats to national and global military, economic and environmental security.
In other words, efficient water use will involve greatly increased use of water-saving technologies and practices that do more with less water. This will also decrease the burden on wastewater plants, reduce the need for expensive dams and water transfer projects that destroy wildlife habitats and displace people, slow depletion of groundwater aquifers, and save energy and money.
IV.1. Using irrigation water efficiently:
Globally, only 40% of the water used reaches crops, the other 60% is wasted. We cannot forget that this water embedded in commodities such as grains has a value, it is called “virtual water”.
Most irrigation systems distribute water from a groundwater well or a surface water source and allow it to flow by gravity through unlined ditches in cropfields so that the water can be absorbed by crops. This flood irrigation method, or gravity flow method delivers far more water than needed for crop growth and typically allows only 60% of the water to reach crops because of evaporation, seepage, and runoff.
This conventional gravity flow irrigation system could have its efficiency improved by 80% with the use of surge or time-controlled valves, which send water down irrigation ditches in pulses instead of in a continuous stream, therefore reducing water use by 25%. Also, the use of soil moisture detectors to water crops should occur only when needed. For example, some farmers in Texas bury a $1 cube of gypsum, the size of a lump of sugar, at the root zone of crops. Wires embedded in the gypsum are run back to a small, portable meter that indicates soil moisture. Farmers using this technique can use 33-66% less irrigation water with no change in crop yields.
More efficient irrigation system that can reduce water waste are:
- Center-pivot low-pressure sprinklers: water is pumped from underground and sprayed from mobile boom with sprinkles. This method typically allows 80% of the water input to reach crops and reduces water use over conventional gravity flow systems by 25%;
- Low-energy precision application (LEPA) sprinklers: this form of center-pivot irrigation allows 90-95% of the water input to reach crops by spraying it closer to the ground and in larger droplets than the center-pivot, low pressure system. LEPA sprinklers use 20-30% less energy than low-pressure sprinklers and typically use 37% less water than conventional gravity flow systems; and
- Drip irrigation (or micro irrigation): the technique was created in Israel in the 1960s, with the development, after World War II, of inexpensive, weather-resistant and flexible plastic. It consists of a network of above or below-ground perforated plastic pipes or tubes which small holes or emitters deliver water, at a slow and steady rate, to individual plant roots. This system can raise water efficiency to 90-95% and reduce water use by 37-70%. Besides efficiency, other advantages of drip irrigation are:
- Adaptability: the tubing system can easily be fitted to match the patterns of crops in a fields and left in place or moved to different locations;
- Lower operation costs: it needs 37-70% less energy to pump this water at low pressure and less labor to move sprinkler systems;
- Ability to apply fertilizer solutions in precise amounts: which reduces fertilizer use and waste, salinization, and water pollution from fertilizer runoff;
- An increased crop yield of 20-90% by getting more crop growth per drop; and
- Healthier plants and higher yields because plants are neither underwatered nor overwatered.
Despite these advantages, drip irrigation and center-pivot irrigation are used on only about 1% of the world’s irrigated cropland each. This is because of the higher initial costs in comparison with the conventional gravity flow system. In fact, the capital cost of conventional drip irrigation systems is too high for most poor farmers and for use on low-value row crops; it is economically feasible, however, for high-profit fruit, vegetable, and orchard crops and for home gardens.
The development of new low-cost drip irrigation systems may change this reality. This new system has simple holes instead of emitters, cloth filters instead of costly filtration equipment, and better portability so that each drip line can water 10 rows of crops instead of 1. The company developing this system and the World Bank have been working together to market the system in India and other dry and water-scarce areas. This low-cost drip irrigation system could bring about a revolution in more sustainable irrigated agriculture that would increase food yields, reduce water use and waste, and lessen some of the environmental problems associated with agriculture.
Other ways to reduce water waste in irrigation crops are: lining canals bringing water to irrigation ditches, leveling fields with lasers, irrigating at night to reduce evaporation, using soil and satellite sensors and computer systems to monitor soil moisture and add water only when necessary, polyculture, organic farming, growing water efficient crops using drought-resistant and salt-tolerant cop varieties, irrigating with treated urban waste water, and importing water intensive crops and meat.
Since 1950, water-short Israel has used many of these techniques to slash irrigation water waste by about 84% while irrigating 44% more land. Israel now treats and reuses 65% of its municipal sewage water for crop production and plans to increase this to 80% by 2025. The government has also gradually removed most water subsidies to raise the price of irrigation water to one of the highest in the world. Israel imports most of its water-intensive wheat and meat, and concentrates on growing fruits, vegetables and flowers that need less water.
However, many of the world’s poor farmers cannot afford to use most of the modern technological methods for increasing irrigation and irrigation efficiency. Such farmers increase irrigation by using small-scale and low-cost traditional technologies such as: pedal-powered treadle pumps to move water through irrigation ditches (widely used in Bangladesh), animal-powered irrigation pumps, buckets with holes for drip irrigation, check dams, ponds and tanks to
collect rainwater for irrigation, terracing[14] to reduce water loss on crops that grow on steep terrain, and cultivating seasonally waterlogged wetlands, delta lands, and valley bottoms.
IV.2. Using homes, businesses and industries’ water efficiently:
Two decades of droughts in California has shown that water demand can be cut by 50% for homes, 60% for parks, and 20% for businesses without economic hardships. Reducing water use and waste can also save money. Between 1987 and 1998, Boston, Massachusetts, reduced total water demand by 24% by fixing leaky pipes, installing water saving fixtures, and educating the public about how to save water. This allowed the city to avoid diverting two large rivers to supply more water, which would have cost two to three times more than its water conservation program.
Ways to use water more efficiently in industries, homes and businesses include the following:
- Redesigning manufacturing processes: a paper mill in Hedera, Israel, uses one-tenth as much water as most of the world’s other paper mills, and a German paper plant nearby eliminated water use by completely recycling and purifying its water[15]. Manufacturing aluminum from recycled scrap rather than virgin ore can reduce water needs by 97%. Although water use n the United States quadrupled between 1950 and 1998, industrial use dropped by 20% because of increased efficiency and water reuse.
- Replacing green lawns in arid and semiarid regions with vegetation adapted for a dry climate: this form of landscaping with rocks and plants that need less water and are adapted to the growing climate conditions is called xeriscaping. It reduces water use by 30-85%, and sharply reduces inputs of labor, fertilizers, and fuel and the production of polluted runoff, air pollution, and yard wastes.
- Using drip irrigation to water gardens and other vegetation around homes and businesses.
- Fixing leaks in water mains, pipes, toilets, and faucets: leaks waste about half of the water supply in many cities in developing countries and 20-35% of water withdrawn from public supplies in the United States and the Unites Kingdom. In water-short Cairo, Egypt, people often wade across streets ankle deep in water because of leaky water pipes. Leaks from toilet valves, dripping faucets, and aging pipes account for about one-tenth of the water used in a typical U.S. household.
- Using water meters to monitor and charge for municipal water use: in Boulder, Colorado, introducing water meters reduced water use by more than one-third. About one-fifth of all U.S. public water systems do not have meters and charge a single low rate for almost unlimited use of high-quality water. Many apartment dwellers have little incentive to conserve water because their water use is included in the rent.
- Having ordinances requiring water conservation in water-short cities: because of such ordinances, the desert city of Tucson, Arizona, consumes half as much water per person as Las Vegas, a desert city with less rainfall and less emphasis on water conservation[16].
- Requiring or encouraging the use of water-saving toilets and showerheads: since 1994, all new toilets in the United States must use no more than 6 liters (1.6 gallons) per flush, and similar laws have been passed in Mexico and in Ontario, Canada. A low-flow showerhead costing about $20 saves about $34-56 per year in water heating costs. Audits conducted by students in Brown University’s environmental studies program showed that the school could save $44,000 a year by using low-flow showerheads in dormitories. A California water utility cut per capita water use by 40% in one year by giving rebates to customers switching to water-saving toilets and showerheads.
- Using washing machines that load from the front and not from the top: these machines use 40-75% less water, make clothes last longer because they are not agitated, and save money.
- Reusing gray water from bathtubs, showers, bathroom sinks, and clothes washers for irrigating lawns and nonedible plants and raising fish: about 70-75% of the water used by a typical house could be reused as gray water. In the United States, California has become the first state to legalize reuse of gray water to irrigate landscapes. About 65% of the wastewater in Israel is reused.
- Collecting and using rainwater for flushing toilets, irrigating gardens, watering lawns and putting out fires: In Tokyo, Japan, large tanks on top of 579 city buildings capture and use rainwater.
- Installing or leasing systems that purify and completely recycle wastewater from houses, apartments, or office buildings: In Tokyo, Japan, all the water used in the Mitsubishi’s 60-story office building is purified for reuse by an automated recycling system[17].
IV.3. The price of water:
One of the major causes of water waste is government subsidies of water supply projects that create artificially low water prices. In fact, by heavily subsidizing water governments give out the false message that it is abundant and can afford to be wasted. It is not easy as a political platform to try to cut down such subsidies, and therefore this may never be used as a governmental policy because farmers, industries and others benefiting from it argue that such subsidies promote settlement and agricultural production in arid and semiarid areas, stimulate local economies, and help lower prices of food and manufactured goods for consumers. Other causes of water waste are the laws regarding water resources (see footnote 8) and fragmented watershed management, as opposed to integrated management (see footnote 11).
An example of the artificial aquatic wonderland created by government subsidies to water is Las Vegas, Nevada, where the water usage rate per inhabitant is estimated to be the highest in the world. The city is a paradise of large trees, green lawns and golf courses, waterfalls, and swimming pools located in the middle of the Mojave Desert. Residents in this arid area have to apply 3 meters (10 feet) of water on a lawn each year to keep it green, in comparison to the 10 centimeters (4 inches) of rainfall a year. On the other extreme, Tucson, Arizona, in the Sonora Desert, is an example of water conservation. Although this city gets 3 times more rainfall than Las Vegas, it has began a strict water conservation program in 1976, which includes raising water rates 500% for some residents.
Raising the price of water for domestic and industrial consumers (as Israel and Tucson have done) is one way to reduce wasteful water use. One might think that charging more for water supplied by public water systems would hurt the poor. Instead, this usually lowers the cost of water for the poor because most are paying 10 to 12 times more per liter of water to buy it from private water vendors[18] than citizens receiving often purer water from public systems.
According to the Worldwatch Institute, on average, a ton of water used in industry generated goods or services worth about $14,000 – about 70 times more than the economic values from using the same amount of water to grow grain. The value of virtual water (water embedded in commodities such as grains) is also to be taken into account.
V. The quality of drinking water:
The frog does not drink up
the pond in which it lives.
Old Inca Proverb
Unlike the population of about 54 countries mostly in North America and Europe, where there are safe drinking water standards, about one-fourth of people in developing countries do not have access to clean drinking water. In China, an estimated 700 million people drink contaminated water, and only 6 of China’s largest cities provide drinking water that meets government standards. Contaminated drinking water is considered a key factor in the doubling of liver disease and cancer deaths in China since 1970. In Russia, half of all tap water is unfit to drink, and a third of the aquifers are too contaminated for drinking purposes. About 290 million African – about equal to the entire U.S. population – do not have access to safe drinking water.
In many poor villages in developing countries, people get their water form shallow groundwater wells that are easily contaminated, nearby polluted river water, or mudholes used by both animals and humans.
In most urban slums in developing countries, drinking water is pumped in or the poor there cannot afford a house connection. Such poor urban dwellers, must either: drink contaminated water from rivers or other sources, or buy it from street vendors at an average cost 12 times more per liter than middle-class families pay for water piped to their houses. A 1999 study by the World Commission on Water for the 21st Century found that much of the water sold by urban street vendors is drawn from polluted rivers or other contaminated sources.
Even in the United States, bottled water is not the answer, because an estimated one-third of the bottled water purchased in the U.S is contaminated with bacteria. It is also more expensive than drinking tap water.
The United Nations estimates that it would cost about $25 billion a year over 8-10 years to bring low-cost safe water and sanitation to the 1.4 billion people – one of every four – who do not have access to clean drinking water. These expenditures could prevent many of the 5 million deaths (including 2 million children under age 5) and 3.4 billion cases of illness caused each year by unsafe water. Currently, the world is spending only about $8 billion a year on clean water efforts. The $17 billion shortfall is about equal to what people in Europe and the United States spend each year on pet food or about what the world spends every eight days for military purposes.
Treatment of water for drinking by city dwellers is much like wastewater treatment. Areas that depend on surface water usually store it in a reservoir for several days to improve clarity and taste by allowing the dissolved oxygen content to increase and suspended matter to settle out. The water is then pumped to a purification plant, where it is treated to meet government drinking water standards. Usually the water is run through sand filters and activated charcoal before it is disinfected. In areas with very pure groundwater sources, little treatment is necessary.
V.1. Purifying water:
Conventional methods for purifying water include, but are not limited to:
- Filtration: the process in which suspended matter is removed from a liquid through a medium which is permeable to the liquid but not to the suspended material. This treatment process, under the control of qualified operators, removes solid (particulate) matter from water by means of porous media such as sand or a man-made filter; it is often used to remove particles that contain pathogens;
- Chlorination: the application of chlorine (CL2) or one of its compounds to water or wastewater, often for disinfection or oxidation purposes;
- Denitrification: the removal of nitrate ions (NO3-) from soil or water; involves anaerobic biological reduction of nitrate to nitrogen gas. The process reduces desirable fertility of an agricultural field, or the extent of undesirable aquatic weed production in aquatic environments; and
- Biological aeration: any active or passive process, by which intimate contact between air and liquid is assured, generally by spraying liquid in the air, bubbling air through water (in an aeration tank), or mechanical agitation of the liquid to promote surface absorption of air.
Researches are trying to find cheaper and more simple ways to purify drinking water in developing countries, where 80% of the diseases is caused by drinking contaminated water, like for example the use of:
- Ultra-violet (UV) light: a simple device that uses UV light to kill disease-causing organisms in drinking water has been recently developed by Ashok J. Gadgil, a physicist at California’s Lawrence Berkeley National Laboratory and his colleagues. When water from a well or hand pump (in a village or household in a developing country) is passed through this tabletop system, UV radiation from a mercury vapor lamp zaps germs in the water. This $300 device weights only 7 kilograms (15 pounds) and can disinfect 57 liters (15 gallons) of water per minute at a very low cost. It draws only 40 watts of power, supplied by solar cells, and can run unsupervised in remote areas of developing countries.
- Horseradish: recently, Pennsylvania State soil biochemists discovered that chopped horseradish mixed with hydrogen peroxide (H2O2) helps rid contaminated water of organic pollutants called phenols. The horseradish contains an enzyme that speeds up the breakdown of the phenols.
- Slimes: Judith Bender and Peter Philips at Clark Atlanta University in Georgia have found a way to use slime produced by cyanobacteria to decompose chlorinated hydrocarbons that contaminate drinking water. Within three weeks, a slimy, floating bacterial mat can surround and decompose a glob of toxic chlordane (a pesticide banned in the United States as a suspected carcinogen). Such slime mats can also remove lead, copper, chromium, cadmium, selenium, and other toxic metals from water.
Despite the creativity of such methods, a more effective approach to deal with the problem of water contamination, however, is to shift the emphasis from pollution clean-up to pollution prevention. This can be done by reducing the toxicity or volume of pollutants (for example, replacing organic solvent-based inks and paints with water-based materials), reusing wastewater instead of discharging it (for example, reusing treated wastewater for irrigation), and recycling pollutants (for example, cleaning up and recycling contaminated solvents for reuse) instead of discharging them.
V.2. Recycling water:
Typically, recycling strategies have been implemented only when additional resources are not readily available. Recycling has also been perceived as a way of obtaining second-hand resources whose quality must be inferior. However, this has been changing. Companies around the world are ever more concerned about recycling their wastewater. Two examples of this assertive are:
- In Hawaii, USA, the Honoliuli Wastewater Facility produces recycled water (R-1) for lanscape irrigation, and a second type, reverse osmosis water (RO) for industrial purposes. The facility diverts the wastewater through the plant, where it is re-purified and disinfected (although not turned into drinkable water) and then sold to a variety of customers, like golf courses, parks and agricultural fields;
- In the field of semiconductor wafer manufacturing, rapid industry growth, increases in wafer size, and new technologies will increase water usage. The National Technology Road Map for Semiconductors has identified targets through 2012 for decreasing the net use of feed water, as well as for lowering water purification costs. In order to achieve such goals, recycling is on the table. Indeed, when the quality of ultrapurified water recycled from wafer rinsing is compared with the quality of typical municipal water supplies, it becomes apparent that most of the spent rinse water is superior. Recycling is not, therefore, in this case, a compromise. Because recycled water is purer, manufacturers save on purification and disposal costs.
Creative ways for recycling water are also being tested for smaller structures. Michael Burton, a British electrical engineer, has turned his interest in water conservation into a device for recycling water anywhere in the world. The so-called “Aquasaver” system recovers bath and shower water, filters soap and other impurities, and then stores the water for flushing toilets, washing cars, and watering gardens. The system is designed to meet building requirements of countries throughout the world; it can be integrated with domestic housing as well as commercial buildings such as apartments, small hotels, and resort facilities. Aquasaver saves up to 50% of annual water consumption in standard homes and up to 40% in hotels and other large structures, according to the manufacturer.
Aquasaver operates independently of water main networks, avoiding the problem of cross-contamination between drinking water and recycled gray water. It is a chemical-free, automatic system that uses 12-volt direct current power for its pumps. It can also be run on solar power.
Despite the creativity of this method, a better approach to water management is to focus on all the four R’s of the resources conservation rule, in which recycling is the last step in the process: REDUCE, REFUSE, REUSE, RECYCLE.
VI. The Amazon Basin:
The Amazon Region is a great plain only 55 meters above sea level, and occupies areas in six South American Countries (Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela). It represents: 20% of the earth’s total surface; 4/10 of South America; 3/5 of Brazil; 1/5 of the world’s freshwater; 1/3 of the world’s rainforests. Sixty nine percent of the Amazon belongs to Brazil, encompassing nine States (Para, Amazonas, Maranhao, Goias, Mato Grosso, Acre, Amapa, Rondonia and Roraima). Its territory within Brazil measures 4.871.000 square kilometers[19]. Only 12.5% of this territory has been deforested, especially in the 1980s[20]. Its lands, waters and forests are the home of 10 million inhabitants, only 2.5/1000 of the global population, its demographic density is 2 inhabitants per square kilometer[21].
The Amazon “hides” 50% of the world’s biodiversity. There are approximately from 1.000 to 5.000 species of fish (most of which still have no scientific knowledge) and more than 30 million species of insects. On a single plant scientists discovered over 80 species of ants (more than double the number of species encountered in Great Britain). The forest is composed of 78% acid and low fertility soils, the average temperature on the region is 26 degrees Celsius. Annually the Amazon receives 15 trillions cubic meters of rain, 48% of the rainwater evaporates from the surface and 52% runs to the thousands of rivers and streams.
The Amazon produces annually 96 tons of oxygen, which represents 0,000008% of the earth’s atmosphere. Although it has a small contribution on the global oxygen supply, the Amazon is a great filter of carbon dioxide through its more than 5.000 species of trees[22]. There are approximately 40 to 300 different species of trees per hectare[23]. That is why the agricultural development and population growth in the area can modify the climate and the environment on a global scale.
The rivers are the great beauty of the Amazon Region. The most famous one, the Amazon River has a water volume of 100 to 300 cubic meters per second. This means that the daily water consumption of a city with 2.000 inhabitants could be supplied with one second of this river’s water flow. In fact, the Amazon River alone holds 17% of the world’s fresh water. It can reach up to 100 meters deep and its force can be felt 1.000 km into the Atlantic Ocean. It has an incline of only 2 cm/1000m, mainly caused by the hydraulic pressure itself than by the land inclination.
Besides the Amazon River, there are three types of waters in the Amazon Basin: white/yellow water (Solimoes, Amazon, Madeira, etc) with visibility of 0.1 to 0.5 meters and pH of 6.5 to 7.0; dark/black water (Negro, Urubu, etc) with visibility of 1.50 to 2.50 meters and pH of 3.5 to 4.0; and green/blue water (Tapajos, Trombetas, etc) with visibility of over 4 meters and pH of 4.0 to 7.0. The low pH measures[24] on the waters of the Amazon Basin are related to the characteristics of the soil on the drainage basins, the color and turbid ness caused by the carrying of suspended material during the rainy season. The acid waters present humic substances such as humic acid and fulvic acid.
The gigantic hydrologic web that forms the Amazon Basin covers approximately 7.400.000 km2. Its geological formation is very old, from the Cambrian and Cretaceous until the Quaternary Periods. During the Tertiary Period, sediments were deposited in the Basin through erosion processes from the Brazilian Central Mountains and from the Guyanas’ Mountains. These sediments are relatively poor in nutrients, especially alkaline-terrain – calcium and magnesium – therefore, they originated extremely poor soils and very acid waters, except for those rivers and streams that were formed from the carboniferous area and from the Andes, which are characterized as neutral waters and have a bigger concentration of nutrients, including calcium and magnesium.
There is a theory that says that the great Amazonian rivers used to flow towards the Pacific and the Caribbean, millions of years ago, before the formation of the Andes Mountain Range, which blocked the free flow of the water. On this giant natural dam, the rivers formed the Great Amazonian Lake, the largest lake ever to exist on earth, until geological conditions generated the flow to the opposite side, towards the Atlantic. Therefore, this theory indicates that there used to be in the region a much larger quantity of water than we have now.
An intricate web of rivers and streams supports the Amazon Basin[25], each being a complete micro system presenting different patterns of drainage. These micro systems are the habitats of aquatic and semi-aquatic organisms. In fact, the area occupied by smaller water bodies is bigger than the area occupied by the great rivers. However, because of the smaller water volume these streams are more vulnerable to environmental changes. The deforestation of its margins is capable of deeply altering their hydrological and hydro chemical characteristics, with devastating effects on the animal and vegetal biota.
The hydrological regime of the Basin is governed, in general, by the geomorphology of its drainage basins, by its soil typology and by the volume (quantity and intensity) of rain in the region. During the “rainy season” or “winter” (from November to April) even the smaller water bodies present a relatively great volume of water, whereas during the “dry season” or “summer” (from May to October) these surface waters transform into narrow streams, and sometimes into completely dry land. These conditions, considered normal in the Amazon Region, are responsible for the close connection and interdependence between the water and the terrestrial environment, making the Basin extremely susceptible to different forms of impact especially related to human activities on the drainage basins.
The Amazon River is the axle of a hydro system right on the Equator of earth, receiving waters from the two hemispheres, each with different rainy seasons. That is why for the most part of the year it receives the floods from the north and then from the south, and the permanent flooded meadows on the Amazon River occupy 40 km on each margin, twice the size of Austria. Every year tons of grasses and nutrients are deposited by the rivers on these meadows to fertilize the soil, and there is where the natives farm their crops and raise their cattle. The meadows are the most precious ecological ambient on the Amazon, for the shelter that it provides to hundreds of species and for its rich-nutrient soil[26].
The fish is the main source of animal protein consumed by the populations that inhabit the Amazon, especially isolated communities with no access to other types of goods. Fishing is a daily activity performed with primitive equipment and methods such as: artesian nets and fish poles, or the use of “timbo” (a poisonous root extracted from the forest and washed in the water to kill the fish). The use of timbo is prohibited for its great toxicity, nonetheless its common usage by some indigenous communities. These communities however never use the timbo on the smaller lakes and ponds because they are breeding areas for the fish, and therefore are preserved by the Indians.
The fish swim upward the river to spawn. Some species like the “piramutaba” swim 3,000 km towards the west, spawn and then swim back to the original place[27]. Other species like the “tambaqui” migrate to the flooded lakes where there is plenty of fallen fruits from the trees above. During the dry season, the tambaqui migrates back to the rivers and looses weight until the next rainy season. The Amazonian orchard formed by these flooded areas are also the habitat of 1/3 of all species of birds in the region (ducks, parrots, araras, etc), turtles, manatees[28], and otters.
The rivers of the Amazon are also great highways of commerce - specially for grains, minerals, wood and oil -, and most of the times the only highway to connect the forest and its people to the outside world. The volume of load transported every year is 12 million tons (only 0.48% of the total load transported through rivers in the whole world). The shipping system there is called “roll-on-roll-off” integrated to the terrestrial highway web. The many harbors are administered by the Ministry of Transportation (part of the Executive branch), through the Department of Harbors and Hydro ways.
Since much of the Amazon Basin rivers flow in the tropics and in high latitudes, it is virtually inaccessible to people and economic activity, and it is likely to remain so for the foresseable future, because water is difficult and expensive to transport for long distances. Therefore, unfortunately, there are no studies or proposals of exporting drinking water from the Amazon Basin. In contacting Dr. Assad Darwich (Ph.D), Coordinator or Aquatic Biology Research, from the National Institute of Amazonian Research, in Manaus, Amazonas, Brazil, he informed that he has no notice of any project regarding the exportation of drinking water from the Amazon Basin. The same information was given by the Brazilian Association of Water Resources (abrh).
VII. Conclusions:
- Water is one of the most abundant natural resources we have and also one of the most poorly managed;
- The water distribution in the world does not match the distribution of population, diving the world’s countries in water-haves and have-nots and creating millions of environmental refugees;
- Two factors that affect the availability of water in the planet are the hydrologic cycle and the phenomenon of global warming;
- As we use water resources faster than they can replenish we cause water stress;
- Water scarcity can lead to water wars, especially in the Middle East, where the problem is increased by religious and political conflicts;
- The ways to increase the water supply have benefits, but can also cause huge environmental problems, such as the Aral Sea shrinkage;
- To improve water efficiency we need to involve farmers, city residents, businesses and industries, and also reduce government subsidies to water which create the false impression that water is abundant and cheap and can be wasted;
- To improve drinking water quality we need to upgrade the existing methods of purifying and recycling water, and also value creative solutions;
- Although the Amazon Basin is a huge repository of freshwater, there are no projects for the exportation of this valuable natural resource from that region, because of the difficulty in transportation since most of the rivers flow in inaccessible areas.
VIII. Bibliography:
- G. Tyler Miller, Jr. Living in the Environment. 12th ed., 2001.
- The Columbia Encyclopedia. Edition 6, Columbia University Press (2000) pp. 40571-40610.
- Dan Johnson. The Coming Resource Wars. The Futurist (2001) 35:5-16.
- Gard Binney. Running on Empty. The Ecologist (2001) 31:4-63.
- Norman Myers. The Century Ahead (the 21st century begins with earth’s resources already strained by its human population). UN Chronicle (2000) 37:3-8.
- John M. Swomley. When Blue Becomes Gold. The Humanist (2000) 60:5-5.
- Joe Bower. Water Wars (water use legislation). Audubon (2000) 102:2-16.
- Sandra Postel. Trobled Waters. The Sciences (2000) 40:2-19.
- Stephen P.A. Brown and Daniel Wolk. Natural Resources Scarcity and Technological Change. Economic and Financial Review (2000) 2000:1-2.
- Andrew Nikiforuk. Putting a tag price on the planet (environmental perspective). Canadian Business (1997) 70:10-83(1).
- Janet N. Abramovits. Learning to value nature’s free services (includes related article on the importance of groundwater). The Futurist (1997) 31:4-39(4).
- Franklin M. Fisher and Hossein Askari. Optimal Water Management in the Middle East and Other Regions. Finance and Development (2001) 38:3-52.
- Sandra L. Postel and Aaron T. Wolf. Dehydrating Conflict (possible wars over water). Foreign Policy (2001) p.60.
- Catherine Dold. Water and health, hand-in-hand for a day (World Water Day). Bulletin of the World Health Organization (2001) 79:5-486.
- Les Roberts, Yves Chartier, Oana Chartier, Grace Malenga, Michael Toole and Henry Rodka. Keeping clean water clean in a Malawi refugee camp: a randomized intervention trial. Bulletin of the World Health Organization (2001) 79:4-280.
- Peter H. Gleick. Global Water. Environment (2001) 43:2-18.
- Patrick McCormick. Water, water everywhere? (importance of water). U.S. Catholic (2000) 65:12-46.
- Christine Drake. Water resource conflicts in the Middle East (scarcity of water resources are sources of quarrels in the Middle East). World and I (2000) 15:9-298.
- Ed Metcalfe. Nor any drop to drink. The Ecologist (2000) 30:5-46.
- John Cooper. Water Wars. CMA Management (2000) 74:5-19.
- Ines Capdevilla. Rising Population Faces Shrinking Water Supply (World Water Commission report). Insight on the News (2000) 16:16-30.
- Jo-Ansie van Wyk. A River Runs Through: water scarcity in Southern Africa. New Zealand International Review (2000) 25:3-20.
- Thomas Omestad, David Makovsky and Rachel Stroumsa. The struggle over water (water is a obstacle to peace in the Middle East). U.S. News & World Report (2000) 128:4-32.
- Jonathan W. Bulkley. Global Overview: Water Resources and Distribution Issues. Arab Studies (ASQ) (2000) 22:2-1.
- Gar Smith. Water Wars, Water Cures. Earth Island Journal (2000) 15:1-30.
- William Suratt, Mark Maimone and Thomas Missimer. Soothing water woes with desalinization. American City & County (2000) 115:1-61.
- Gilbert F. White. Water Sciences and Technology. Environment (2000) 42:1-30.
- Yvonne Acosta. Progress can’t always be measured in pipelines (water shortage as a global problem). UN Chronicle (1999) 36:1-44(1).
- Sandra Postel. Dividing the waters (global freshwater supply). MIT’s Technology Review (1997) 100:3-54(9).
- Leslie Alan Horvits. More precious than oil (water and global geopolitics)(includes related article on desalinization). Insight on the News (1997) 13:10-42(2).
- J.A. Allan. Virtual Water: a strategic resource. Ground Water (1998) 36:4-545(2).
- Dan Johnson. Averting a water crisis: the era of taking water for granted is ending. The Futurist (1998) 32:2-7(1).
- Wendy Drake. Take It Without a Grain of Salt (use of desalinization to provide water to Israel and US). Environment (2001) 43:2-5.
- Jacy L. Youn. Waste Not, Want Not (Hawaii recycles wastewater). Hawaii Business (2000) 46:5-60.
- Anthony Veltri, John DeGenova, Patricia O’Hara and Gerald L. Airth. Recycling Spent Ultrapure Rinse Water – A Case Study in the Use of a Financial Analysis Tool. Journal of Environmental Health (2000) 63:4-17.
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[1] The desalinization process will be discussed in III.4.
[2] The main processes in the water cycle are: (1) evaporation – conversion of water into vapor, (2) transpiration – evaporation from leaves of water extracted from soil by roots and transported throughout the plant, (3) condensation – conversion of water vapor intro droplets of liquid water, (4) precipitation – rain, sleet, hail and snow, (5) infiltration - movement of water into soil, (6) percolation – downward flow of water through soil and permeable rock formations to groundwater storage areas called aquifers, and (7) runoff – downslope surface movement back to the sea to resume the cycle. The water cycle is powered by energy from the sun and by gravity. Throughout the hydrologic cycle, many natural processes act to purify water. Evaporation and subsequent precipitation act as a natural distillation process that removes impurities dissolved in water. As water flows above ground through streams and lakes, and below ground in aquifers, it is naturally filtered and purified by chemical and biological processes. Thus, the hydrologic cycle promotes natural renewal of water quality.
[3] A total of 7.6% of Canada is covered by water. Water contributes anywhere from $12 to $38 billion to Canada’s economy annually. But even there, the Canadian government is urging its provinces to ban large-scale exports of freshwater. In 1997, Ontario decided to allow a local company to remove 156 million gallons of Lake Superior water every year for five years to export to Asia, but in May 1999 the province bowed to public pressure and reversed the decision.
[4] The Amazon Basin will be discussed in VI.
[5] Worldwide, about 70% of all water withdrawn each year from rivers, lakes and aquifers is used to irrigate 17% of the world’s croplands. Industry uses about 20% of the water withdrawn each year, and city residents use the remaining 10%.
[6] In the Bible, Genesis 2:7 tells us that God formed the first human from the soil. The word adam means a “creature of the earth”. But Genesis 1:1-3 reminds us that all creation began with water, with God hovering over the deep. At the beginning of life we float in our mother’s water. The prophecy of the Judgement Day, of a world burning with fire from Heaven is depicted in the Book of Apocalypse, by the Apostle John.
7 Desiccation also refers to loss of water from pores spaces in sediments through compaction or through evaporation caused by exposure to air; or to refer to a long period between pluvial (wet) episodes.
[7] This specific project will be discussed in III.1.
[8] Some ecological services provided by rivers are: deliver nutrients to the sea to sustain coastal fisheries, deposit silt that maintains deltas, purify water, renew and nourish wetlands, provide habitats for aquatic life and conserve species diversity. Currently, the services are given little or no monetary value when the costs and benefits of dams and reservoir projects are assessed. According to environmental economists, attaching even crudely estimated monetary values to these ecosystem services would help sustain them.
[9] Laws regulating access to and use of surface water differ in eastern and western United States. In most of the East, water use is based on the doctrine of riparian rights, which gives anyone whose land adjoins a flowing stream the right to use water from the stream as long as some is left for downstream landowners. In the West, water is regulated by the principle of prior appropriation, by which the first user of water from a stream establishes a legal right for continued use of the amount originally withdrawn. If there is a shortage, later users are cut off in order until there is enough water to satisfy the demands of the earlier users. Most groundwater use is based on common law, which holds that it belongs to whoever owns the land above. When many users tap the same aquifer, it becomes a common-property resource (this can create a tragedy of the commons). A system of legally protected water rights allows individuals owning rights to sell, trade, or lease them to make money, ease water shortages, or protect the ecosystem services of the river. For example, some water-short areas in the western U.S. are paying nearby farmers to install more efficient irrigation methods in exchange for the water the farmers save. Private organizations and the government are also buying up water rights and using them to help restore aquatic environments by returning the water to rivers and wetlands. However, water markets must be regulated to avoid excessive water prices (especially for the poor) and inequalities in water distribution.
[10] Lowering of the water table when a well is drilled into an aquifer occurs when a cone of depression in the water is formed if groundwater is pumped to the surface faster than it can flow through the aquifer to the well. If this excessive water removal continues, the water table falls.
[11] See the Ogallala aquifer example. This is a huge aquifer in southwestern U.S. where in some areas groundwater is being pumped out 8-10 times faster than its natural recharge rate. The northernmost states (Wyoming, North and South Dakota, and parts of Colorado) still have ample water supplies, but in the southern states where the aquifer is thinner it has been depleted rapidly, especially in the Texas High Plains. The depletion of the Ogallala aquifer is increased by government subsidies encouraging the growth of water-thirsty cotton in the lower basin, and providing crop-disaster payments and tax breaks in the form of groundwater depletion allowances, with larger breaks for heavier groundwater use. Farmers and city’s inhabitants need to join efforts to protect this nonrenewable resource, the first ones can improve irrigation efficiency and switch to crops that need less water, and the second ones can install water-saving toilets and shower heads in their homes and also convert their lawns to plants that can survive in an arid climate with little watering.
[12] An integrated watershed management has regional water authorities based on natural watershed boundaries, who own, finance and manage all water supply, water pollution control, and waste treatment facilities in its region.
[13] Terracing is a soil conservation method that can reduce soil erosion on steep slopes, each of which is converted into a series of broad, nearly level terraces that run across the land contour. Terracing retains water for crops at each level and reduces soil erosion by controlling runoff.
[14] Methods of recycling and purifying water will be discussed in V.
[15] See IV.3
[16] More about the recycling of water will be discussed in V.2.
[17] See the discussion about bottled water in V
[18] Including the six countries, the Amazon territory is 7.584.421 km2.
[19] Until the end of World War II the human presence in the Amazon was almost unfelt, non capable of significantly changing the natural environment. After the 1950s however, the Brazilian federal government started to incentive migration to populate the region.
[20] The Amazon has been inhabited since the immemorial times. On the 16th century, with the arrival of European settlers, there were millions of indigenous people living in the region.
[21] North America, for example, has 650 species of trees.
[22] North America has 4 to 25 species of trees per hectare.
[23] The concentration of hydrogen ions (H+) in a water solution is a measure of its acidity or alkalinity (pH). On a pH scale of 0 to 14, acids have a pH less than 7, bases have a pH greater than 7, and a neutral solution has a pH of 7. Each whole number drop in pH represents a 10-fold increase in acidity.
[24] The Amazon River alone has more than 1,100 tributaries. Near Manaus, the Negro River is the most important of these tributaries, reaching up to 100 meters of depth.
[25] Although these areas have been suffering on the last decades, specially around Manaus and the estuary region of the Amazon River, because of inconsequent logging, cattle and buffalo farms, and commercial fishery.
[26] The total distance corresponds to the distance between New York and Paris.
[27] The manatee is the biggest mammal on the region, it eats daily 50 kg of grass (10% of its weight).
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