Water is a basic need for all living organisms, since it constitutes around 70% (?) of our biomass and must be replenished on a regular basis. Humans also need it for purposes of cooking and of hygiene. In addition, water is required to grow food, whether in the form of naturally occurring rainwater, river water, groundwater, soil water etc., or brought to the growing plants via irrigation systems. Water is required in food processing and numerous other industries, either to be incorporated into the final product (e.g., beer), or as a cooling agent, or as a medium for chemical reactions, or for cleaning purposes. Finally, water is also used for purposes of waste disposal, to carry wastes downriver and into the sea. The latter use of course leads to water pollution, impairing its usefulness for other purposes and degrading or destroying animal and plant habitats.
This “resources” section focuses on the issues faced in maintaining the quality and quantity of water resources. Issues of how to best deliver water for human consumption and how to best treat sewerage are treated in the section on water as a “need.”
“Clean water to drink, for cleanliness, for cooking and as habitat” This section covers the need for water, and discusses the relation of this need to other needs.
Relationships to other resources
“Air quality near the Earth’s surface” Pollutants can move from water to air and vice versa; hence water and air quality affect each other.
“Gaseous composition of the atmosphere, including greenhouse gases” The oceans can absorb as well as release carbon dioxide and other greenhouse gases, and thus affect how the greenhouse effect responds to human pollutants. Increased levels of dissolved carbon dioxide in the ocean have important effects on marine organisms, such as corals and other organisms with hard parts made of calcium carbonate.
“Land for agriculture and forestry” Numerous chemical substances, including fertilizers and pesticides, are used in agriculture and forestry, with impacts on water quality in ground and surface waters, including eutrophication and “dead zones.” Agriculture and forestry often have impacts on soil erosion, with impacts on downstream turbidity and sedimentation patterns.
“Land for nature preservation” Generally speaking, the use of chemicals as well as soil erosion should be minimized on land for nature preservation, leading to high water quality. Conversely, the preservation of sensitive animal or plant species requires high water quality to be maintained not only inside areas devoted to nature preservation, but also in upstream areas.
“Land used for mining” Mining often has extremely adverse effects on water quality by bringing toxic minerals to the surface that would otherwise be safely underground, or by employing toxic substances in order to extract minerals from the ore (e.g., mercury or cyanide used to obtain gold). Mining can also disrupt the normal flow of water through a landscape. Finally, some forms of mining demand huge amounts of water, which may be contaminated in the process.
“Land used for industrial manufacturing and energy generation” Many industrial processes use water as a material input, as a solvent, or as a cooling agent; if there is no closed-loop cycle, some of this water may be released into the environment in polluted form. Many industries also dump waste into rivers or the sea. Some industrial or manufacturing processes require water of high purity, and may compete with household consumption of the same water (for example, Coca Cola bottling plants in India).
“Urban (residential and commercial) land” Large amounts of water are needed by urban populations – almost all of which eventually becomes waste water which has to be treated if it is not to contaminate fresh and saltwater ecosystems.
“Land used for waste disposal” Liquid and soluble substances can leak out from waste disposal sites and thus pollute ground and surface waters. Only with great technical precautions (and often continual maintenance) can such contamination be prevented. This is one more reason why waste should be minimized.
“Fossil fuels” The mining of fossil fuels can cause serious water quality problems, such as acid mine drainage from abandoned coal mines. Fossil fuels and their residues can contaminate water, particularly dramatically in the case of large oil spills, but on a daily basis in ports.
“Nuclear fuels” The mining, processing and reprocessing of radioactive minerals and nuclear materials poses immense problems for water quality. After final disposal, highly radioactive waste will pose a threat to water quality and the biosphere for untold millennia.
“Solar and wind energy” Although the manufacture of solar and wind energy equipment, including the associated mining of metals, poses threats to water quality, the collecting of solar or wind energy itself does not pollute air or water. Hence, solar and wind energy pose relatively few risks for water quality.
“Energy from water (rivers, tides, ocean currents)” Moving water can provide energy for human use. As in solar and wind energy, the construction of the needed equipment is likely to cause water pollution, but the collection of hydropower usually does not. However, the impoundment of water behind large dams, and the alteration of currents and tides due to the presence of large structures, can have significant impacts on ecosystems and the plants, animals and people within them.
“Geothermal energy” and “Energy from biological sources (wood and other fuels, organic waste)” As in solar and wind energy, the construction of the needed equipment is likely to cause water pollution. The collection of geothermal and biomass energy may or may not cause water pollution, depending on the type of system in place.
“Animal power” and “Human power (e.g., cycling, seesaws to power water pumps)” These types of power use typically have minimal effects on water quality.
“Minerals” The mining of all kinds of minerals typically has adverse effects on water quality, though those can be mitigated depending on specific details of the type of mineral mined, the type of ore, and site-specific considerations.
“Living things (plants, animals, fungi, micro-organisms)” All living things on Earth require water in order to survive. Many live in the water and are thus constantly exposed to any pollutants in that water. It is therefore of critical importance to the diversity of life on Earth that water quality be protected.
“Physical, human-made assets” Buildings, transportation infrastructure, and all the built structure of cities and towns can, create a huge burden on water resources, as regards their water demand, generation of waste water, and impacts on water flows (rainwater cannot penetrate hard surfaces, and is instead channeled to places where it may increase erosion or flooding). With appropriate design, these problems can, however, be mitigated or even turned into assets, as in rainwater harvesting.
Understanding patterns of abundance and scarcity
Water, a most basic substance for all life on Earth, is extremely versatile. It exists on our planet in liquid, gaseous and solid form, and forms key parts of the lithosphere (the rocky layer near the surface of the Earth), the hydrosphere (the bodies of water covering the Earth's surface), and the atmosphere (the air). Water in its liquid form may have low concentrations of salts (freshwater) or high (saltwater), affecting which life forms can live within that water or can drink it. Almost all chemical processes of life involve water as a solvent or as a reagent. The presence or absence of water is among the first things we recognize in any landscape.
Water moves about across the surface of the planet and in the atmosphere, and is transformed from one form to another, in what is called the “hydrological cycle.” This is an integral part of the weather systems that affect us every day, whether it rains or shines. A useful introductory treatment of the hydrological cycle and of the climate system can be found in Pidwirny's online Physical Geography text.1
Human activities can affect where and when how much water is to be found, and whether it suffices for our purposes (i.e., whether it is considered scarce) in numerous ways. The total consumption of water can approach or exceed the amount available in a given place (either from annual river flow or from groundwater), and then it is important to know who uses water for which purposes, and whether substantial amounts of water are wasted, in order to search for ways to conserve water. Water extracted from a river or lake may be returned to that river (usually further downstream), though often in polluted form or at a higher temperature, affecting the water quality. However, in the case of “consumptive” water uses, the water is not returned to that river system. The most important example of consumptive water use is crop irrigation in arid conditions, in which case a large portion of the irrigation water evaporates (this water does come down to Earth as rainwater eventually, but far away from where it evaporated). Some irrigation water does return to the river, but it may have picked up large amounts of salts from the subsoil, leading to problems of salinization. Agricultural practices in general may lead to increased soil erosion, carrying nutrient-rich sediments downstream. Runoff from agricultural land may also carry with it excess fertilizers that have been applied to the land. Such nutrient-rich waters can promote the rapid growth of algae near the surface; dead remains of algae drift to the bottom of slow-moving lake or sea waters, where they decay, using up dissolved oxygen, in a process called “eutrophication.” The levels of oxygen can decline to the point that there are “dead zones” where few or no fish species can survive. The disposal of wastes, including sewerage from cities, wastes from large-scale livestock operations, urban runoff from the streets, industrial wastes in solid or liquid form, municipal solid waste, and hazardous and nuclear wastes, can further degrade water quality. These wastes may be disposed either directly into water bodies, or on or in the ground from where it can leach into the groundwater and from there into surface water bodies. In severe cases, such pollution can make water unusable for long distances downstream of a city, and make it uninhabitable by most fish species and other aquatic life.
Water may be transported over long distances to places of high demand and insufficient local supply, such as large cities or to mining industries that cannot be located close to water sources. This can have major impacts on water availability in the source regions; for example, water transfers to California contribute to the problems of water quantity and quality in the Colorado River. Within smaller distances, humans also modify how water flows, by building dikes, levees, and other flood control structures, by building dams and impoundments, and by dredging river channels. These alter where erosion occurs along riverbanks and seashores, where sediments are deposited, and where subsidence occurs (the settling down of old sediments, where they are not reinforced by new sedimentation). Mines also affect how water flows through a landscape.
Climate change, specifically global warming as a result of the emissions of greenhouse gases, also entails dramatic changes in the availability of water. Rainfall patterns are likely to change, leading either to more or less rainfall in particular regions. Polar ice caps (specifically in Greenland and the West Antarctic peninsula) and glaciers worldwide are melting, adding to the amount of water in the sea. In addition, the warming of the sea is leading to the expansion of the water (warmer water takes up a larger volume). Both of these processes are contributing to sea-level rise, placing coastal communities at risk worldwide. The melting of permafrost in northern North America and in Siberia is also likely to release large amounts of methane (now frozen in the ground in the form of clathrates) into the atmosphere. Since methane is a powerful greenhouse gas, this is likely to accelerate global warming.
Many of the adverse impacts of humans on water availability or water quality have been known for decades, if not centuries. In some cases, people have managed to improve conditions; for example, rivers such as the Rhine and the Thames are now cleaner than they were in the 1960s and 1970s. However, in many more cases, things are getting worse rather than better, despite all our environmental knowledge. This raises questions about why we don't act on our knowledge, about our decision-making processes. Among the most important reasons for poor decision-making concerning water is the nature of our property rights in water.
Water epitomizes the observation that everything is connected with everything else; it connects all living things and all places on Earth. Meanwhile, our notions about private property deny this reality. It is assumed that what I do on my private property is only my business, just as what you do on yours is your business. However, what we do with the water that flows across our land does affect others, and if we make decisions about using that water without reference to the interests of others, this will lead to all kinds of problems. Therefore, decisions about how water is to be used cannot just be left to private property owners. There must be some forms of decision-making and control by larger entities.
The larger entities can be government bodies (local to national governments, specialized agencies, or regional water authorities), intergovernmental bodies and treaty organizations (particularly important regarding international waters and rivers that cross national borders), and civic organizations (such as associations of users of irrigation water in an area). These organizations should effectively represent the interests of all relevant stakeholders, which means that they should be inclusive in their membership, and democratically organized. Where the potential impacts of water use can extend over large areas, the voices of affected people in distant places need to be brought into the process. However, at the same time as these considerations might lead one to advocate for large organizations with broad spatial reach, it is difficult to ensure that all affected people feel adequately represented in such large organizations; they may also become highly bureaucratic and unable to engage with local intricacies. Hence, it is important to create a tiered system, with different kinds of decisions and rules made and enforced at different levels. At each level, it is important to think through the design principles that are needed for effective management of the commons. That is the challenge we now face around the world where the management of water resources is concerned.
Approaches to creating greater abundance
Drip irrigation and other kinds of water-saving irrigation
Closed-loop water use systems in industry
Wastewater treatment systems
Solar water desalinization etc.
Water as Commons
Water commons Note that this page focuses mainly on drinking water provision, hence water as need.
Additional references will be needed here for addressing water quality and quantity in groundwater, rivers, lakes, estuaries, the sea, glaciers, and ice caps.
approaches to government regulation, taxation, fines etc.
various forms of property rights in water; tradable water use rights
river basin authorities
intergovernmental organizations (e.g., concerning Mediterranean Sea; international river basins)
international commons trusts?