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124-452: This is a system of water supply that allows water to be transported over long distances in hot dry climates without losing much of the water to evaporation . The system has the advantage of being resistant to natural disasters such as floods and to deliberate destruction in war. Furthermore, it is almost insensitive to the levels of precipitation, delivering a flow with only gradual variations from wet to dry years. Karez are constructed as

248-471: A 12 mm pipe, plus ball valve, and then supply the house on 22 or 28 mm pipes. Gravity water has a small pressure (say 1 ⁄ 4 bar in the bathroom) so needs wide pipes to allow for higher flows. This is fine for baths and toilets but is frequently inadequate for showers. A booster pump or a hydrophore is installed to increase and maintain pressure. For this reason urban houses are increasingly using mains pressure boilers ("combies") which take

372-666: A Ministry of Public Works (such as in Ecuador and Haiti ), a Ministry of Economy (such as in German states) or a Ministry of Energy (such as in Iran ). A few countries, such as Jordan and Bolivia , even have a Ministry of Water. Often several Ministries share responsibilities for water supply. In the European Union, important policy functions have been entrusted to the supranational level. Policy and regulatory functions include

496-714: A brass foundry in Rotherham . The first documented use of sand filters to purify the water supply dates to 1804, when the owner of a bleachery in Paisley, Scotland , John Gibb, installed an experimental filter, selling his unwanted surplus to the public. The first treated public water supply in the world was installed by engineer James Simpson for the Chelsea Waterworks Company in London in 1829. The practice of water treatment soon became mainstream, and

620-566: A component of effective policy for health protection." In 1990, only 76 percent of the global population had access to drinking water. By 2015 that number had increased to 91 percent. In 1990, most countries in Latin America, East and South Asia, and Sub-Saharan Africa were well below 90%. In Sub-Saharan Africa, where the rates are lowest, household access ranges from 40 to 80 percent. Countries that experience violent conflict can have reductions in drinking water access: One study found that

744-611: A conflict with about 2,500 battle deaths deprives 1.8% of the population of potable water. Typically in developed countries , tap water meets drinking water quality standards , even though only a small proportion is actually consumed or used in food preparation. Other typical uses for tap water include washing, toilets, and irrigation . Greywater may also be used for toilets or irrigation. Its use for irrigation however may be associated with risks. Throughout history, people have devised systems to make getting and using water more convenient. Living in semi-arid regions, ancient Persians in

868-493: A consumption level of 15 cubic meters per month. Few utilities do recover all their costs. According to the same World Bank study only 30% of utilities globally, and only 50% of utilities in developed countries, generate sufficient revenue to cover operation, maintenance and partial capital costs. According to another study undertaken in 2006 by NUS Consulting, the average water and sewerage tariff in 14 mainly OECD countries excluding VAT varied between US$ 0.66 per cubic meter in

992-497: A crew of four workers can excavate a horizontal length of 40 m (130 ft) per day. When the vertical shaft reaches 40 m (130 ft), they can excavate only 20 meters horizontally per day and at 60 m (200 ft) in depth this drops below 5 horizontal meters per day. In Algeria, a common speed is just 2 m (6.6 ft) per day at a depth of 15 m (49 ft). Deep, long qanats (which many are) require years and even decades to construct. The excavated material

1116-476: A critical situation in the water supply system. Still, kahrezes are the main source of potable and irrigation water for the community. Water supply Water supply is the provision of water by public utilities , commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes . Public water supply systems are crucial to properly functioning societies. These systems are what supply drinking water to populations around

1240-467: A deep valley, it will have the same nominal pressure, however each consumer will get a bit more or less because of the hydrostatic pressure (about 1 bar/10 m height). So people at the bottom of a 30-metre (100 ft) hill will get about 3 bars more than those at the top. The effective pressure also varies because of the pressure loss due to supply resistance, even for the same static pressure. An urban consumer may have 5 metres of 15-mm pipe running from

1364-701: A few cases such multi-utilities also collect solid waste and provide local telephone services. An example of such an integrated utility can be found in the Colombian city of Medellín . Utilities that provide water, sanitation and electricity can be found in Frankfurt , Germany (Mainova), in Casablanca , Morocco and in Gabon in West Africa. Multi-utilities provide certain benefits such as common billing and

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1488-514: A great degree of autonomy. In the United States regulatory agencies for utilities have existed for almost a century at the level of states, and in Canada at the level of provinces. In both countries they cover several infrastructure sectors. In many U.S. states they are called Public Utility Commissions . For England and Wales, a regulatory agency for water ( OFWAT ) was created as part of

1612-429: A huge amount of capital investment in infrastructure such as pipe networks, pumping stations and water treatment works . It is estimated that in developing countries investments of at least US$ 200 billion have to be made per year to replace aging water infrastructure to guarantee supply, reduce leakage rates and protect water quality. International attention has focused upon the needs of developing countries . To meet

1736-424: A long time to fill a bath but suit the high back pressure of a shower. A great variety of institutions have responsibilities in water supply. A basic distinction is between institutions responsible for policy and regulation on the one hand; and institutions in charge of providing services on the other hand. Water supply policies and regulation are usually defined by one or several Ministries, in consultation with

1860-410: A mandate to settle complaints by consumers that have not been dealt with satisfactorily by service providers. These specialized entities are expected to be more competent and objective in regulating service providers than departments of government Ministries. Regulatory agencies are supposed to be autonomous from the executive branch of government, but in many countries have often not been able to exercise

1984-496: A poor or very poor quality of service. Continuity of water supply is taken for granted in most developed countries but is a severe problem in many developing countries, where sometimes water is only provided for a few hours every day or a few days a week; that is, it is intermittent . This is especially problematic for informal settlements , which are often poorly connected to the water supply network and have no means of procuring alternative sources such as private boreholes . It

2108-452: A qanat is stored in a reservoir, typically with night flow stored for daytime use. An ab anbar is an example of a traditional Persian qanat-fed reservoir for drinking water. The qanat system has the advantage of being resistant to natural disasters such as floods, and to deliberate destruction in war. Furthermore, it is almost insensitive to the levels of precipitation, delivering a flow with only gradual variations from wet to dry years. From

2232-415: A qanat system had to be carefully situated, to make best use of the slow flow of water. In Iran, there were subterranean mills at Yazd and Boshruyeh ; at Taft and Ardestan mills were placed at the outflow from the qanat, before irrigation of the fields. Qanats used in conjunction with a wind tower can provide cooling as well as a water supply. A wind tower is a chimney-like structure positioned above

2356-468: A series of well-like vertical shafts, connected by a gently sloping tunnel. This taps into underground water and delivers it to the surface by gravity, without need for pumping. The vertical shafts along the underground channel are for maintenance purposes, and water is typically used only once it emerges from the daylight point. The qanats still create a reliable supply of water for human settlements and irrigation in hot, arid , and semi-arid climates, but

2480-433: A side shaft through the easily penetrated sandstone (presumably in the direction of greatest water seepage) into the hill of Ayn-Manâwîr (also written Ayn-Manawir  [ fr ] to allow collection of additional water. After this side shaft had been extended, another vertical shaft was driven to intersect the side shaft. Side chambers were built, and holes bored into the rock—presumably at points where water seeped from

2604-466: A single city, town or municipality . However, in many countries municipalities have associated in regional or inter-municipal or multi-jurisdictional utilities to benefit from economies of scale . In the United States these can take the form of special-purpose districts which may have independent taxing authority. An example of a multi-jurisdictional water utility in the United States is WASA ,

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2728-521: A small dam at the end. The width is approximately 60 cm (24 in), but the height ranges from 5 to 9 meters; it is likely that the qanat was deepened to enhance seepage when the water table dropped (as is also seen in Iran). From there the water was used to irrigate fields. There is another instructive structure located at the Kharga Oasis. A well that apparently dried up was improved by driving

2852-407: A small extent of variable costs that depend on the amount of water consumed (mainly energy and chemicals). Almost all service providers in the world charge tariffs to recover part of their costs. Water supply is a separate topic from irrigation , the practice and systems of water supply on a larger scale, for a wider variety of purposes, primarily agriculture . Water supply systems get water from

2976-400: A sufficient flow is available to justify construction. If these prerequisites are met, the route is laid out aboveground. Equipment must be assembled. The equipment is straightforward: containers (usually leather bags), ropes, reels to raise the container to the surface at the shaft head, hatchets and shovels for excavation, lights, and spirit levels or plumb bobs and string. Depending upon

3100-517: A sustainability perspective, qanats are powered only by gravity and thus have low operation and maintenance costs. Qanats transfer fresh water from the mountain plateau to the lower-lying plains with saltier soil. This helps to control soil salinity and prevent desertification . The qanat should not be confused with the spring-flow tunnel typical to the mountainous area around Jerusalem . Although both are excavated tunnels designed to extract water by gravity flow, there are crucial differences. Firstly,

3224-557: A sustained improvement track, but many others keep falling further behind best practice. Benchmarking the performance of utilities allows the stimulation of competition, establish realistic targets for improvement and create pressure to catch up with better utilities. Information on benchmarks for water and sanitation utilities is provided by the International Benchmarking Network for Water and Sanitation Utilities. The cost of supplying water consists, to

3348-514: A ten-meter width, with length reckoned by the size of plot that the available water will irrigate. The qanats are called kariz in Dari (Persian) and Pashto and have been in use since the pre-Islamic period. It is estimated that more than 9,370 karizes were in use in the 20th century. The oldest functional kariz which is more than 300 years old and 8 kilometers long is located in Wardak province and

3472-576: A trickle of water or so high that it leads to damage to plumbing fixtures and waste of water. Pressure in an urban water system is typically maintained either by a pressurised water tank serving an urban area, by pumping the water up into a water tower and relying on gravity to maintain a constant pressure in the system or solely by pumps at the water treatment plant and repeater pumping stations. Typical UK pressures are 4–5 bar (60–70 PSI ) for an urban supply. However, some people can get over eight bars or below one bar. A single iron main pipe may cross

3596-485: A typical consumption of 15 cubic meters per month vary between less than US$ 1 and US$ 12 per month. Water and sanitation tariffs, which are almost always billed together, can take many different forms. Where meters are installed, tariffs are typically volumetric (per usage), sometimes combined with a small monthly fixed charge. In the absence of meters, flat or fixed rates—which are independent of actual consumption—are being charged. In developed countries, tariffs are usually

3720-759: A utility serving Washington, D.C. and various localities in the state of Maryland . Multi-jurisdictional utilities are also common in Germany, where they are known as "Zweckverbaende", in France and in Italy. In some federal countries, there are water service providers covering most or all cities and towns in an entire state, such as in all states of Brazil and some states in Mexico (see Water supply and sanitation in Mexico ). In England and Wales , water supply and sewerage

3844-516: A utility to better locate distribution losses (technical objective). Fourth, it allows suppliers to charge for water based on use, which is perceived by many as the fairest way to allocate the costs of water supply to users. Metering is considered good practice in water supply and is widespread in developed countries, except for the United Kingdom . In developing countries it is estimated that half of all urban water supply systems are metered and

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3968-423: A variety of locations after appropriate treatment, including groundwater ( aquifers ), surface water ( lakes and rivers ), and the sea through desalination . The water treatment steps include, in most cases, purification , disinfection through chlorination and sometimes fluoridation . Treated water then either flows by gravity or is pumped to reservoirs , which can be elevated such as water towers or on

4092-418: A very large extent, of fixed costs (capital costs and personnel costs) and only to a small extent of variable costs that depend on the amount of water consumed (mainly energy and chemicals). The full cost of supplying water in urban areas in developed countries is about US$ 1–2 per cubic meter depending on local costs and local water consumption levels. The cost of sanitation (sewerage and wastewater treatment )

4216-434: A viable solution including Rainwater harvesting and Stormwater harvesting where policies are eventually tending towards a more rational use and sourcing of water incorporation concepts such as "Fit for Purpose". Water supply service quality has many dimensions: continuity; water quality ; pressure; and the degree of responsiveness of service providers to customer complaints. Many people in developing countries receive

4340-622: Is also a risk that staff are appointed mainly on political grounds rather than based on their professional credentials. International standards for water supply system are covered by International Classification of Standards (ICS) 91.140.60. Comparing the performance of water and sanitation service providers ( utilities ) is needed, because the sector offers limited scope for direct competition ( natural monopoly ). Firms operating in competitive markets are under constant pressure to out perform each other. Water utilities are often sheltered from this pressure, and it frequently shows: some utilities are on

4464-793: Is an Arabic word that means "channel". In Persian , the words for "qanat" are kārīz (or kārēz ; كاريز ) and is derived from earlier word kāhrēz ( كاهریز ). The word qanāt ( قنات ) is also used in Persian. Other names for qanat include kahan ( Persian : کهن ); Kahn ( Balochi ); kahriz/kəhriz ( Azerbaijan ); khettara ( Morocco ); Galerías , minas or viajes de agua (Spain); falaj ( Arabic : فلج ) ( United Arab Emirates and Oman ); foggara/fughara ( North Africa ). Alternative terms for qanats in Asia and North Africa are kakuriz , chin-avulz , and mayun . According to most sources, qanat technology

4588-559: Is an essential governance reform in order to reduce the high levels of Unaccounted-for Water (UAW) and to provide the finance needed to extend the network to those poorest households who remain unconnected. Partnership arrangements between the public and private sector can play an important role in order to achieve this objective. An estimated 10 percent of urban water supply is provided by private or mixed public-private companies, usually under concessions , leases or management contracts . Under these water service contract arrangements

4712-454: Is another US$ 1–2 per cubic meter. These costs are somewhat lower in developing countries. Throughout the world, only part of these costs is usually billed to consumers, the remainder being financed through direct or indirect subsidies from local, regional or national governments (see section on tariffs). Besides subsidies water supply investments are financed through internally generated revenues as well as through debt. Debt financing can take

4836-455: Is estimated that about half of the population of developing countries receives water on an intermittent basis. Drinking water quality has a micro-biological and a physico-chemical dimension. There are thousands of parameters of water quality. In public water supply systems water should, at a minimum, be disinfected—most commonly through the use of chlorination or the use of ultraviolet light—or it may need to undergo treatment, especially in

4960-448: Is insulated from arbitrary political intervention; and whether there is an explicit mandate and political will to allow the service provider to recover all or at least most of its costs through tariffs and retain these revenues. If water supply is the responsibility of a department that is integrated in the administration of a city, town or municipality, there is a risk that tariff revenues are diverted for other purposes. In some cases, there

5084-565: Is still providing water to nearly 3,000 people. Many of these ancient structures were destroyed during the Soviet–Aghan War and the War in Afghanistan . Maintenance has not always been possible. The cost of labour has become very high, and maintaining the kariz structures is no longer possible. Lack of skilled artisans who have the traditional knowledge also poses difficulties. A number of

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5208-582: Is supplied almost entirely through ten regional companies. Some smaller countries, especially developed countries, have established service providers that cover the entire country or at least most of its cities and major towns. Such national service providers are especially prevalent in West Africa and Central America, but also exist, for example, in Tunisia , Jordan and Uruguay (see also water supply and sanitation in Uruguay ). In rural areas, where about half

5332-465: Is supported by the historian Albert T. Olmstead . There are four main oases in the Egyptian desert. The Kharga Oasis is one that has been extensively studied. There is evidence that as early as the second half of the 5th century BCE water brought in qanats was being used. The qanats were excavated through water-bearing sandstone rock, which seeps into the channel, with water collected in a basin behind

5456-402: Is used, has more than one qanat. Fields and gardens are located both over the qanats a short distance before they emerge from the ground and below the surface outlet. Water from the qanats define both the social regions in the city and the layout of the city. The water is freshest, cleanest, and coolest in the upper reaches, and more prosperous people live at the outlet or immediately upstream of

5580-452: Is usually transported by means of leather bags up the vertical shafts. It is mounded around the vertical shaft exit, providing a barrier that prevents windblown or rain driven debris from entering the shafts. These mounds may be covered to provide further protection to the qanat. From the air, these shafts look like a string of bomb craters. The qanat's water-carrying channel must have a sufficient downward slope that water flows easily. However

5704-643: Is very common for a qanat to start below the foothills of mountains, where the water table is closest to the surface. From this source, the qanat tunnel slopes gently downward, slowly converging with the steeper slope of the land surface above, and the water finally flows out above ground where the two levels meet. To connect a populated or agricultural area with an aquifer, qanats must often extend for long distances. Qanats are sometimes split into an underground distribution network of smaller canals called kariz. Like qanats, these smaller canals are below ground to avoid contamination and evaporation. In some cases water from

5828-716: The Gelasian Stage, which was formerly considered part of the Neogene Period and Pliocene Epoch. This was later revised to 2.58 mya. The Anthropocene was proposed as a third epoch as a mark of the anthropogenic impact on the global environment starting with the Industrial Revolution , or about 200 years ago. The Anthropocene was rejected as a geological epoch in 2024 by the International Union of Geological Sciences (IUGS),

5952-718: The Holocene (11.7 thousand years ago to today); a proposed third epoch, the Anthropocene , was rejected in 2024 by IUGS , the governing body of the ICS. The Quaternary is typically defined by the Quaternary glaciation , the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused. In 1759 Giovanni Arduino proposed that

6076-871: The Indian subcontinent for a long time. Cotton appears in the Inquiry into Plants by Theophrastus and is mentioned in the Laws of Manu . As transregional trade networks expanded and intensified, cotton spread from its homeland to India and into the Middle East. One theory is that the qanat was developed to irrigate cotton fields, first in what is now Iran, where it doubled the amount of available water for irrigation and urban use. Because of this, Persia enjoyed larger surpluses of agricultural products, thus increasing urbanization and social stratification. The qanat technology subsequently spread from Persia westward and eastward. In

6200-748: The Millennium Development Goals targets of halving the proportion of the population lacking access to safe drinking water and basic sanitation by 2015, current annual investment on the order of US$ 10 to US$ 15 billion would need to be roughly doubled. This does not include investments required for the maintenance of existing infrastructure. Once infrastructure is in place, operating water supply and sanitation systems entails significant ongoing costs to cover personnel, energy, chemicals, maintenance and other expenses. The sources of money to meet these capital and operational costs are essentially either user fees, public funds or some combination of

6324-443: The province of Khorasan have been recorded with vertical shafts of up to 275 m (902 ft). The vertical shafts support construction and maintenance of the underground channel as well as air interchange. Deep shafts require intermediate platforms to facilitate the process of removing soil. The construction speed depends on the depth and nature of the ground. If the earth is soft and easy to work, at 20 m (66 ft) depth

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6448-527: The 1st millennium BC used qanat system to gain access to water in the mountains. Early Rome had indoor plumbing, meaning a system of aqueducts and pipes that terminated in homes and at public wells and fountains for people to use. Until the Enlightenment era , little progress was made in water supply and sanitation and the engineering skills of the Romans were largely neglected throughout Europe. It

6572-580: The Iranian qanat. The foggara is dug into the foothills of a fairly steep mountain range such as the eastern ranges of the Atlas Mountains . Rainfall in the mountains enters the aquifer and moves toward the Saharan region to the south. The foggara, 1 to 3 km (0.62 to 1.9 mi) in length, penetrates the aquifer and collects water. Families maintain the foggara and own the land it irrigates over

6696-628: The Pleistocene includes a portion of what was, prior to 2009, defined as the Pliocene . Quaternary stratigraphers usually worked with regional subdivisions. From the 1970s, the International Commission on Stratigraphy (ICS) tried to make a single geologic time scale based on GSSP 's, which could be used internationally. The Quaternary subdivisions were defined based on biostratigraphy instead of paleoclimate . This led to

6820-735: The United States and the equivalent of US$ 2.25 per cubic meter in Denmark. However, water consumption is much higher in the US than in Europe. Therefore, residential water bills may be very similar, even if the tariff per unit of consumption tends to be higher in Europe than in the US. A typical family on the US East Coast paid between US$ 30 and US$ 70 per month for water and sewer services in 2005. In developing countries, tariffs are usually much further from covering costs. Residential water bills for

6944-527: The World Bank the average ( mean ) global water tariff is US$ 0.53 per cubic meter. In developed countries the average tariff is US$ 1.04, while it is only U$ 0.11 in the poorest developing countries. The lowest tariffs in developing countries are found in South Asia (mean of US$ 0.09/m3), while the highest are found in Latin America (US$ 0.41/m3). Data for 132 cities were assessed. The tariff is estimate for

7068-573: The arid coastal desert of Peru, a technology of water supply similar to that of the qanats, called puquios , was developed. Most archaeologists believe that the puquios are indigenous and date to about 500 CE, but a few believe they are of Spanish origin, brought to the Americas in the 16th century. Puquios were still in use in the Nazca region in the 21st century. In arid and semi-arid regions, owing to high evaporation, transportation routes were in

7192-475: The beginning of the 21st Century, especially in areas of urban and suburban population centers, traditional centralized infrastructure have not been able to supply sufficient quantities of water to keep up with growing demand. Among several options that have been managed are the extensive use of desalination technology, this is especially prevalent in coastal areas and in "dry" countries like Australia . Decentralization of water infrastructure has grown extensively as

7316-441: The best forms of public management. As Ryutaro Hashimoto , former Japanese Prime Minister, notes: "Public water services currently provide more than 90 percent of water supply in the world. Modest improvement in public water operators will have immense impact on global provision of services." Governance arrangements for both public and private utilities can take many forms (Kurian and McCarney, 2010). Governance arrangements define

7440-427: The case of surface water . Water quality is also dependent of the quality and level of pollution of the water source. Water pressures vary in different locations of a distribution system. Water mains below the street may operate at higher pressures, with a pressure reducer located at each point where the water enters a building or a house. In poorly managed systems, water pressure can be so low as to result only in

7564-473: The cool tunnel walls/water and by the transfer of latent heat of evaporation as water evaporates into the air stream. In dry desert climates this can result in a greater than 15 °C reduction in the air temperature coming from the qanat; the mixed air still feels dry, so the basement is cool and only comfortably moist (not damp). Wind tower and qanat cooling have been used in desert climates for over 1,000 years. By 400 BCE, Persian engineers had mastered

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7688-437: The destination to which the water will be delivered into the soil and works toward the source (the test well). Vertical shafts are excavated along the route, separated at a distance of 20–35 m (66–115 ft). The separation of the shafts is a balance between the amount of work required to excavate them and the amount of effort required to excavate the space between them, as well as the ultimate maintenance effort. In general,

7812-414: The downward gradient must not be so great as to create conditions under which the water transitions between supercritical and subcritical flow . If this occurs, the waves that result can result in severe erosion that can damage or destroy the qanat. The choice of the slope is a trade off between erosion and sedimentation. Highly sloped tunnels are subject to more erosion as water flows at a higher speed. On

7936-467: The effort. There were still functional qanat systems in 2009. American forces were reported to have unintentionally destroyed some of the channels during expansion of a military base, creating tensions between them and the local community. Some of these tunnels were used to store supplies, and to move men and equipment underground. Qanats have been preserved in Armenia in the community of Shvanidzor , in

8060-644: The emergence of the straits of Bosphorus and Skagerrak during glacial epochs, which respectively turned the Black Sea and Baltic Sea into fresh water lakes, followed by their flooding (and return to salt water) by rising sea level; the periodic filling of the English Channel , forming a land bridge between Britain and the European mainland; the periodic closing of the Bering Strait , forming

8184-728: The establishment of the Glacial Theory. In time, thanks to the refinement of geology, it has been demonstrated that there were several periods of glacial advance and retreat and that past temperatures on Earth were very different from today. In particular, the Milankovitch cycles of Milutin Milankovitch are based on the premise that variations in incoming solar radiation are a fundamental factor controlling Earth's climate. During this time, substantial glaciers advanced and retreated over much of North America and Europe, parts of South America and Asia, and all of Antarctica. There

8308-458: The foggara. The moist air of the agricultural area is drawn into the foggara in the opposite direction to the water run-off. In the foggara it condenses on the tunnel walls and the air passes out of the vertical shafts. This condensed moisture is available for reuse. Qanat irrigation technology was introduced to Egypt by the Achaemenid king Darius I during his reign of 522 BCE-486 BCE, which

8432-437: The following: In the United States , the typical single family home uses about 520 L (138 US gal) of water per day (2016 estimate) or 222 L (58.6 US gal) per capita per day. This includes several common residential end use purposes (in decreasing order) like toilet use, showers , tap (faucet) use, washing machine use, leaks , other (unidentified), baths , and dishwasher use. During

8556-457: The form of credits from commercial Banks, credits from international financial institutions such as the World Bank and regional development banks (in the case of developing countries), and bonds (in the case of some developed countries and some upper middle-income countries). Almost all service providers in the world charge tariffs to recover part of their costs. According to estimates by

8680-447: The form of qanats, which led groundwater to consumption areas along underground tunnels. In the long run, the qanat system is not only economical but also sustainable for irrigation and agricultural purposes.… The ground water flow was known to depend on grain size of sediments, and, therefore, the tunnels in qanats are filled in with coarser material than the surrounding host geological formations. The qanats are constructed mainly along

8804-481: The geological strata of northern Italy could be divided into four successive formations or "orders" ( Italian : quattro ordini ). The term "quaternary" was introduced by Jules Desnoyers in 1829 for sediments of France 's Seine Basin that clearly seemed to be younger than Tertiary Period rocks . The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers

8928-465: The globe. Aspects of service quality include continuity of supply, water quality and water pressure. The institutional responsibility for water supply is arranged differently in different countries and regions (urban versus rural). It usually includes issues surrounding policy and regulation, service provision and standardization . The cost of supplying water consists, to a very large extent, of fixed costs (capital costs and personnel costs) and only to

9052-509: The governing body of the ICS. The 2.58 million years of the Quaternary represents the time during which recognisable humans existed. Over this geologically short time period there has been relatively little change in the distribution of the continents due to plate tectonics . The Quaternary geological record is preserved in greater detail than that for earlier periods. The major geographical changes during this time period included

9176-847: The gradient is steeper, underground waterfalls may be constructed with appropriate design features (usually linings) to absorb the energy with minimal erosion. In some cases the water power has been harnessed to drive underground mills . If it is not possible to bring the outlet of the qanat out near the settlement, it is necessary to run a jub or canal overground. This is avoided when possible to limit pollution, warming and water loss due to evaporation. The vertical shafts may be covered to minimize blown-in sand. The channels of qanats must be periodically inspected for erosion or cave-ins, cleaned of sand and mud and otherwise repaired. For safety, air flow must be assured before entry. Some damaged qanats have been restored. To be sustainable, restoration needs to take into account many nontechnical factors beginning with

9300-515: The ground (for indicators related to the efficiency of drinking water distribution see non-revenue water ). Once water is used, wastewater is typically discharged in a sewer system and treated in a sewage treatment plant before being discharged into a river, lake, or the sea or reused for landscaping or irrigation . A water supply network or water supply system is a system of engineered hydrologic and hydraulic components that provide water supply. A water supply system typically includes

9424-426: The house; of its four openings, the one opposite the wind direction is opened to move air out of the house. Incoming air is pulled from a qanat below the house. The air flow across the vertical shaft opening creates a lower pressure (see Bernoulli effect ) and draws cool air up from the qanat tunnel, mixing with it. The air from the qanat is drawn into the tunnel at some distance away and is cooled both by contact with

9548-520: The ice was stored in yakhchals—specially designed, naturally cooled refrigerators. A large underground space with thick insulated walls was connected to a qanat, and a system of windcatchers or wind towers was used to draw cool subterranean air up from the qanat to maintain temperatures inside the space at low levels, even during hot summer days. As a result, the ice melted slowly and was available year-round. Qanats (designated foggaras in Algeria ) are

9672-497: The iron main, so the kitchen tap flow will be fairly unrestricted. A rural consumer may have a kilometre of rusted and limed 22-mm iron pipe, so their kitchen tap flow will be small. For this reason, the UK domestic water system has traditionally (prior to 1989) employed a "cistern feed" system, where the incoming supply is connected to the kitchen sink and also a header/storage tank in the attic . Water can dribble into this tank through

9796-596: The land bridge between Asia and North America ; and the periodic flash flooding of Scablands of the American Northwest by glacial water. The current extent of Hudson Bay , the Great Lakes and other major lakes of North America are a consequence of the Canadian Shield 's readjustment since the last ice age; different shorelines have existed over the course of Quaternary time. The climate

9920-448: The large farmers are abandoning their kariz which has been in their families sometimes for centuries, and moving to tube and dug wells backed by diesel pumps. However, the government of Afghanistan was aware of the importance of these structures and all efforts were made to repair, reconstruct and maintain (through the community) the kariz. The Ministry of Rural Rehabilitation and Development along with national and international NGOs made

10044-669: The legislative branch. In the United States the United States Environmental Protection Agency , whose administrator reports directly to the President, is responsible for water and sanitation policy and standard setting within the executive branch. In other countries responsibility for sector policy is entrusted to a Ministry of Environment (such as in Mexico and Colombia ), to a Ministry of Health (such as in Panama , Honduras and Uruguay ),

10168-421: The lower reaches are the most likely to see substantial reductions in flow. Traditionally qanats are built by a group of skilled laborers, muqannīs , with hand labor. The profession historically paid well and was typically handed down from father to son. The critical, initial step in qanat construction is identification of an appropriate water source. The search begins at the point where the alluvial fan meets

10292-581: The main course of the Ziz River and its subsequent impact on local water tables is said to be one of the many reasons for the loss of half of the khettara. The black berbers ( haratin ) of the south were the hereditary class of qanat diggers in Morocco who build and repair these systems. Their work was hazardous. The foggara water management system in Tunisia, used to create oases, is similar to that of

10416-584: The main losers from this institutional arrangement are the urban poor in these countries. Because they are not connected to the water supply network , they end up paying far more per liter of water than do more well-off households connected to the network who benefit from the implicit subsidies that they receive from loss-making utilities. The fact that we are still so far from achieving universal access to clean water and sanitation shows that public water authorities, in their current state, are not working well enough. Yet some are being very successful and are modelling

10540-432: The mountains or foothills; water is more abundant in the mountains because of orographic lifting , and excavation in the alluvial fan is relatively easy. The muqannīs follow the track of the main water courses coming from the mountains or foothills to identify evidence of subsurface water such as deep-rooted vegetation or seasonal seeps. A trial well is then dug to determine the depth of the water table and determine whether

10664-463: The national government. This is, for example, the case in the countries of continental Europe, in China and India. Water supply service providers, which are often utilities , differ from each other in terms of their geographical coverage relative to administrative boundaries; their sectoral coverage; their ownership structure; and their governance arrangements. Many water utilities provide services in

10788-448: The neighborhood, gardens and fields. The streets normally parallel the jubs and their lateral branches. As a result, the cities and towns are oriented consistent with the gradient of the land; this is a practical response to efficient water distribution over varying terrain. The lower reaches of the canals are less desirable for both residences and agriculture. The water grows progressively more polluted as it passes downstream. In dry years

10912-413: The oases in the 10th century and the residents embraced Islam. The water is metered to the various users through the use of distribution weirs that meter flow to the various canals, each for a separate user. The humidity of the oases is also used to supplement the water supply to the foggara. The temperature gradient in the vertical shafts causes air to rise by natural convection, causing a draft to enter

11036-545: The option to cross-subsidize water services with revenues from electricity sales, if permitted by law. Water supply providers can be either public, private, mixed or cooperative. Most urban water supply services around the world are provided by public entities. As Willem-Alexander, Prince of Orange (2002) stated, "The water crisis that is affecting so many people is mainly a crisis of governance—not of water scarcity ." The introduction of cost-reflective tariffs together with cross-subsidization between richer and poorer consumers

11160-454: The origin of the qanat was a well that was turned into an artificial spring. In contrast, the origin of the spring-flow tunnel was the development of a natural spring to renew or increase flow following a recession of the water table. Secondly, the shafts essential for the construction of qanats are not essential to spring-flow tunnels. A typical town or city in Iran, and elsewhere where the qanat

11284-414: The other hand, less sloped tunnels need frequent maintenance due to the problem of sedimentation. A lower downward gradient also contributes to reducing the solid contents and contamination in water. In shorter qanats the downward gradient varies between 1:1000 and 1:1500, while in longer qanats it may be almost horizontal. Such precision is routinely obtained with a spirit level and string. In cases where

11408-511: The outlet. When the qanat is still below ground, the water is drawn to the surface via wells or animal driven Persian wells . Private subterranean reservoirs could supply houses and buildings for domestic use and garden irrigation as well. Air flow from the qanat is used to cool an underground summer room ( shabestan ) found in many older houses and buildings. Downstream of the outlet, the water runs through surface canals called jubs ( jūbs ) which run downhill, with lateral branches to carry water to

11532-428: The overall low level of water tariffs in developing countries even at higher levels of consumption, most consumption subsidies benefit the wealthier segments of society. Also, high industrial and commercial tariffs can provide an incentive for these users to supply water from other sources than the utility (own wells, water tankers) and thus actually erode the utility's revenue base. Water supply and sanitation require

11656-481: The presence of traces of the passage of a glacier at a considerable distance from the Alps. This idea was initially disputed by another Swiss scientist, Louis Agassiz , but when he undertook to disprove it, he ended up affirming his colleague's hypothesis. A year later, Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects. This idea gained him international fame and led to

11780-541: The privatization of the water industry in 1989. In many developing countries, water regulatory agencies were created during the 1990s in parallel with efforts at increasing private sector participation. (for more details on regulatory agencies in Latin America, for example, please see Water and sanitation in Latin America and the regional association of water regulatory agencies ADERASA. ) Many countries do not have regulatory agencies for water. In these countries service providers are regulated directly by local government, or

11904-523: The problem that the proposed base of the Pleistocene was at 1.805 million years ago, long after the start of the major glaciations of the northern hemisphere. The ICS then proposed to abolish use of the name Quaternary altogether, which appeared unacceptable to the International Union for Quaternary Research (INQUA). In 2009, it was decided to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.588 mya and including

12028-663: The process of selecting the qanat to be restored. In Syria, three sites were chosen based on a national inventory conducted in 2001. One of them, the Drasiah qanat of Dmeir , was completed in 2002. Selection criteria included the availability of a steady groundwater flow, social cohesion and willingness to contribute of the community using the qanat, and the existence of a functioning water-rights system. The primary applications of qanats are for irrigation, providing cattle with water, and drinking water supply. Other applications include watermills, cooling and ice storage. Watermills within

12152-731: The public entity that is legally responsible for service provision delegates certain or all aspects of service provision to the private service provider for a period typically ranging from 4 to 30 years. The public entity continues to own the assets. These arrangements are common in France and in Spain . Only in few parts of the world water supply systems have been completely sold to the private sector ( privatization ), such as in England and Wales as well as in Chile . The largest private water companies in

12276-451: The public sector. They are owned by the state or local authorities, or also by collectives or cooperatives. They run without an aim for profit but are based on the ethos of providing a common good considered to be of public interest. In most middle and low-income countries, these publicly owned and managed water providers can be inefficient as a result of political interference, leading to over-staffing and low labor productivity. Ironically,

12400-658: The qanat (locally khettara ) is also used. On the margins of the Sahara Desert , the isolated oases of the Draa River valley and Tafilalt have relied on qanat water for irrigation since the late 14th century. In Marrakech and the Haouz plain, the qanats have been abandoned since the early 1970s, having dried up. In the Tafilaft area, half of the 400 khettaras are still in use. The 1971 Hassan Adahkil Dam 's build in

12524-417: The qanat. And misreading the soil conditions leads to collapses, which at best require extensive rework and at worst are fatal for the crew. Construction of a qanat is usually performed by a crew of 3–4 muqannīs . For a shallow qanat, one worker typically digs the horizontal shaft, one raises the excavated earth from the shaft and one distributes the excavated earth at the top. The crew typically begins from

12648-412: The relationship between the service provider, its owners, its customers and regulatory entities. They determine the financial autonomy of the service provider and thus its ability to maintain its assets, expand services, attract and retain qualified staff, and ultimately to provide high-quality services. Key aspects of governance arrangements are the extent to which the entity in charge of providing services

12772-651: The rocks—are evident. David Mattingly reports foggara extending for hundreds of miles in the Garamantes area near Germa in Libya : "The channels were generally very narrow – less than 2 feet wide and 5 high – but some were several miles long, and in total some 600 foggara extended for hundreds of miles underground. The channels were dug out and maintained using a series of regularly spaced vertical shafts, one every 30 feet or so, 100,000 in total, averaging 30 feet in depth, but sometimes reaching 130." In southern Morocco,

12896-594: The same for different categories of users and for different levels of consumption. In developing countries, the situation is often characterized by cross-subsidies with the intent to make water more affordable for residential low-volume users that are assumed to be poor. For example, industrial and commercial users are often charged higher tariffs than public or residential users. Also, metered users are often charged higher tariffs for higher levels of consumption (increasing-block tariffs). However, cross-subsidies between residential users do not always reach their objective. Given

13020-565: The setting of tariff rules and the approval of tariff increases; setting, monitoring and enforcing norms for quality of service and environmental protection; benchmarking the performance of service providers; and reforms in the structure of institutions responsible for service provision. The distinction between policy functions and regulatory functions is not always clear-cut. In some countries they are both entrusted to Ministries, but in others regulatory functions are entrusted to agencies that are separate from Ministries. Dozens of countries around

13144-448: The shallower the qanat, the closer the vertical shafts. If the qanat is long, excavation may begin from both ends at once. Tributary channels are sometimes also constructed to supplement the water flow. Most qanats in Iran run less than 5 km (3.1 miles), while some have been measured at ≈70 km (43 miles) in length near Kerman . The vertical shafts usually range from 20 to 200 m (66 to 656 ft) in depth, although qanats in

13268-418: The soil type, qanat liners (usually fired clay hoops) may also be required. Although the construction methods are simple, the construction of a qanat requires a detailed understanding of subterranean geology and a degree of engineering sophistication. The gradient of the qanat must be carefully controlled: too shallow a gradient yields no flow and too steep a gradient will result in excessive erosion, collapsing

13392-458: The source of water for irrigation in large oases like Gourara . The foggaras are also found at Touat (an area of Adrar 200 km from Gourara). The length of the foggaras in this region is estimated to be thousands of kilometers. Although sources suggest that the foggaras may have been in use as early as 200 CE, they were clearly in use by the 11th century after the Arabs took possession of

13516-571: The southern province of Syunik , bordering with Iran. Qanats are named kahrezes in Armenian. There are 5 kahrezes in Shvanidzor. Four of them were constructed before the village was founded. The fifth kahrez was constructed in 2005. Potable water runs through three of them, and two are in poor condition. In the summer, especially in July and August, the amount of water reaches its minimum, creating

13640-430: The technique of storing ice in the middle of summer in the desert. The ice could be brought in during the winters from nearby mountains, but in a more usual and sophisticated method they built a wall in the east–west direction near a yakhchal (ice pit). In winter, the qanat water would be channeled to the north side of the wall, whose shade made the water freeze more quickly, increasing the ice formed per winter day. Then

13764-493: The tendency is increasing. Water meters are read by one of several methods: Most cities are increasingly installing automatic meter reading (AMR) systems to prevent fraud, to lower ever-increasing labor and liability costs and to improve customer service and satisfaction. According to the World Health Organization (WHO), "access to safe drinking-water is essential to health, a basic human right and

13888-616: The three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the Phanerozoic eon. It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and

14012-399: The time span of glaciations classified as the Pleistocene , and includes the present interglacial time-period, the Holocene . This places the start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago ( mya ). Prior to 2009, the Pleistocene was defined to be from 1.805 million years ago to the present, so the current definition of

14136-410: The two. It is also important to consider is the flexibility of the water supply system. Metering of water supply is usually motivated by one or several of four objectives. First, it provides an incentive to conserve water which protects water resources (environmental objective). Second, it can postpone costly system expansion and saves energy and chemical costs (economic objective). Third, it allows

14260-532: The valleys where Quaternary sediments are deposited. Qanats are constructed as a series of well -like vertical shafts , connected by a gently sloping tunnel which carries a water canal . Qanats efficiently deliver large amounts of subterranean water to the surface without need for pumping. The water drains by gravity, typically from an upland aquifer , with the destination lower than the source. Qanats allow water to be transported over long distances in hot dry climates without much water loss to evaporation . It

14384-570: The value of this system is directly related to the quality, volume, and regularity of the groundwater . Much of the population of Iran and other arid countries in North Africa and West Asia historically depended upon the water from qanats; many populated areas are close to the areas where qanats are possible. Common variants of qanat in English include kanat , khanat , kunut , kona , konait , ghanat , ghundat . Qanāh ( قناة )

14508-424: The virtues of the system were made starkly apparent after the investigations of the physician John Snow during the 1854 Broad Street cholera outbreak demonstrated the role of the water supply in spreading the cholera epidemic. Quaternary The Quaternary ( / k w ə ˈ t ɜːr n ə r i , ˈ k w ɒ t ər n ɛr i / kwə- TUR -nə-ree, KWOT -ər-nerr-ee ) is the current and most recent of

14632-400: The world are Suez and Veolia Environnement from France; Aguas de Barcelona from Spain; and Thames Water from the UK, all of which are engaged internationally (see links to website of these companies below). In recent years, a number of cities have reverted to the public sector in a process called " remunicipalization ". 90% of urban water supply and sanitation services are currently in

14756-423: The world have established regulatory agencies for infrastructure services, including often water supply and sanitation, in order to better protect consumers and to improve efficiency. Regulatory agencies can be entrusted with a variety of responsibilities, including in particular the approval of tariff increases and the management of sector information systems, including benchmarking systems. Sometimes they also have

14880-504: The world population lives, water services are often not provided by utilities, but by community-based organizations which usually cover one or sometimes several villages. Some water utilities provide only water supply services, while sewerage is under the responsibility of a different entity. This is for example the case in Tunisia . However, in most cases water utilities also provide sewer and sewage treatment services. In some cities or countries utilities also distribute electricity. In

15004-580: Was a major extinction of large mammals globally during the Late Pleistocene Epoch. Many forms such as sabre-toothed cats , mammoths , mastodons , glyptodonts , etc., became extinct worldwide. Others, including horses , camels and American cheetahs became extinct in North America . The Great Lakes formed and giant mammals thrived in parts of North America and Eurasia not covered in ice. These mammals became extinct when

15128-536: Was developed in ancient Iran by the Persians sometime in the early 1st millennium BCE and slowly spread westward and eastward from there. Other sources suggest a Southeast Arabian origin. Analogous systems appear to have been developed independently in China and in South America (specifically, southern Peru ). A cotton species, Gossypium arboreum , is indigenous to South Asia and has been cultivated on

15252-485: Was in the 18th century that a rapidly growing population fueled a boom in the establishment of private water supply networks in London . London water supply infrastructure developed over many centuries from early mediaeval conduits, through major 19th-century treatment works built in response to cholera threats, to modern, large-scale reservoirs. The first screw-down water tap was patented in 1845 by Guest and Chrimes,

15376-464: Was one of periodic glaciations with continental glaciers moving as far from the poles as 40 degrees latitude . Glaciation took place repeatedly during the Quaternary Ice age  – a term coined by Schimper in 1839 that began with the start of the Quaternary about 2.58 Mya and continues to the present day. In 1821, a Swiss engineer, Ignaz Venetz , presented an article in which he suggested

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