135-535: The Itoshiro Dam is a dam in the city of Ono in Fukui Prefecture , Japan . It was completed in 1968. 35°56′52.4″N 136°43′38.9″E / 35.947889°N 136.727472°E / 35.947889; 136.727472 This article about a dam or floodgate in Chūbu region of Honshu, Japan is a stub . You can help Misplaced Pages by expanding it . Dam A dam is a barrier that stops or restricts
270-548: A harat , which in many cases had gates that could be closed off at night or during disturbances. When the traveller Ibn Battuta first came to Cairo in 1326, he described it as the principal district of Egypt. When he passed through the area again on his return journey in 1348, the Black Death was ravaging most major cities. He cited reports of thousands of deaths per day in Cairo. Although Cairo avoided Europe 's stagnation during
405-463: A province , with Cairo as its capital. For this reason, the history of Cairo during Ottoman times is often described as inconsequential, especially in comparison to other time periods. During the 16th and 17th centuries, Cairo still remained an important economic and cultural centre. Although no longer on the spice route, the city facilitated the transportation of Yemeni coffee and Indian textiles , primarily to Anatolia , North Africa , and
540-401: A balancing compression stress in the downstream face, providing additional economy. For this type of dam, it is essential to have an impervious foundation with high bearing strength. Permeable foundations have a greater likelihood of generating uplift pressures under the dam. Uplift pressures are hydrostatic pressures caused by the water pressure of the reservoir pushing up against the bottom of
675-503: A commander of Turkic origin named Bakbak was sent to Egypt by the Abbasid caliph al-Mu'taz to restore order after a rebellion in the country. He was accompanied by his stepson, Ahmad ibn Tulun , who became effective governor of Egypt. Over time, Ibn Tulun gained an army and accumulated influence and wealth, allowing him to become the de facto independent ruler of both Egypt and Syria by 878. In 870, he used his growing wealth to found
810-533: A dam as "jurisdictional" or "non-jurisdictional" varies by location. In the United States, each state defines what constitutes a non-jurisdictional dam. In the state of Colorado a non-jurisdictional dam is defined as a dam creating a reservoir with a capacity of 100 acre-feet or less and a surface area of 20 acres or less and with a height measured as defined in Rules 4.2.5.1. and 4.2.19 of 10 feet or less. In contrast,
945-495: A dam that directed waterflow. It was finished in 251 BC. A large earthen dam, made by Sunshu Ao , the prime minister of Chu (state) , flooded a valley in modern-day northern Anhui Province that created an enormous irrigation reservoir (100 km (62 mi) in circumference), a reservoir that is still present today. Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on
1080-485: A distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream. The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments, as for example the Daniel-Johnson Dam , Québec, Canada. The multiple-arch dam does not require as many buttresses as the hollow gravity type but requires a good rock foundation because
1215-572: A feature of the city's housing during the later Ottoman period. These apartments were often laid out as multi-story duplexes or triplexes. They were sometimes attached to caravanserais, where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. The oldest partially-preserved example of this type of structure is the Wikala of Amir Qawsun , built before 1341. Residential buildings were in turn organized into close-knit neighbourhoods called
1350-471: A grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam , possibly the largest water barrier to that date, and
1485-734: A major power in the region and was responsible for repelling the advance of the Mongols (most famously at the Battle of Ain Jalut in 1260) and for eliminating the last Crusader states in the Levant. Despite their military character, the Mamluks were also prolific builders and left a rich architectural legacy throughout Cairo. Continuing a practice started by the Ayyubids, much of the land occupied by former Fatimid palaces
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#17330861382471620-505: A minor tributary of the Nieuwe Maas . The central square of Amsterdam, covering the original site of the 800-year-old dam, still carries the name Dam Square . The Romans were the first to build arch dams , where the reaction forces from the abutment stabilizes the structure from the external hydrostatic pressure , but it was only in the 19th century that the engineering skills and construction materials available were capable of building
1755-433: A much higher population density than formal housing. By 2009, over 63% of the population of Greater Cairo lived in informal neighbourhoods, even though these occupied only 17% of the total area of Greater Cairo. According to economist David Sims, informal housing has the benefits of providing affordable accommodation and vibrant communities to huge numbers of Cairo's working classes, but it also suffers from government neglect,
1890-444: A neighbourhood of urban villas with gardens and curved streets. The British occupation was intended to be temporary, but it lasted well into the 20th century. Nationalists staged large-scale demonstrations in Cairo in 1919, five years after Egypt had been declared a British protectorate . Nevertheless, this led to Egypt's independence in 1922 . The King Fuad I Edition of the Qur'an
2025-502: A new administrative capital, al-Qata'i ( Arabic : القطائـع , lit. 'the allotments'), to the northeast of Fustat and of al-Askar. The new city included a palace known as the Dar al-Imara , a parade ground known as al-Maydan , a bimaristan (hospital), and an aqueduct to supply water. Between 876 and 879 Ibn Tulun built a great mosque, now known as the Mosque of Ibn Tulun , at
2160-505: A notable increase in interest in SHPs. Couto and Olden (2018) conducted a global study and found 82,891 small hydropower plants (SHPs) operating or under construction. Technical definitions of SHPs, such as their maximum generation capacity, dam height, reservoir area, etc., vary by country. A dam is non-jurisdictional when its size (usually "small") excludes it from being subject to certain legal regulations. The technical criteria for categorising
2295-516: A political and economic hub for North Africa and the Arab world , with many multinational businesses and organisations, including the Arab League , operating out of the city. In 1979 the historic districts of Cairo were listed as a UNESCO World Heritage Site . In 1992, Cairo was hit by an earthquake causing 545 deaths, injuring 6,512 and leaving around 50,000 people homeless. Cairo's Tahrir Square
2430-627: A profession based on a rigorously applied scientific theoretical framework. This new emphasis was centered around the engineering faculties of universities in France and in the United Kingdom. William John Macquorn Rankine at the University of Glasgow pioneered the theoretical understanding of dam structures in his 1857 paper On the Stability of Loose Earth . Rankine theory provided a good understanding of
2565-524: A relative lack of services, and overcrowding. The "formal" city was also expanded. The most notable example was the creation of Madinat Nasr , a huge government-sponsored expansion of the city to the east which officially began in 1959 but was primarily developed in the mid-1970s. Starting in 1977 the Egyptian government established the New Urban Communities Authority to initiate and direct
2700-560: A series of demonstrations, marches, acts of civil disobedience, and labour strikes. Millions of protesters from a variety of socio-economic and religious backgrounds demanded the overthrow of the regime of Egyptian President Hosni Mubarak. Despite being predominantly peaceful in nature, the revolution was not without violent clashes between security forces and protesters, with at least 846 people killed and 6,000 injured. The uprising took place in Cairo, Alexandria, and in other cities in Egypt, following
2835-561: A settling pond, and a 1,000 m (3,300 ft) canal to a distribution tank. These works were not finished until 325 AD when the dam permitted the irrigation of 25,000 acres (100 km ). Eflatun Pınar is a Hittite dam and spring temple near Konya , Turkey. It is thought to date from the Hittite empire between the 15th and 13th centuries BC. The Kallanai is constructed of unhewn stone, over 300 m (980 ft) long, 4.5 m (15 ft) high and 20 m (66 ft) wide, across
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#17330861382472970-538: A sizeable city existed. The city was important enough that its bishop , Cyrus, participated in the Second Council of Ephesus in 449. The Byzantine-Sassanian War between 602 and 628 caused great hardship and likely caused much of the urban population to leave for the countryside, leaving the settlement partly deserted. The site today remains at the nucleus of the Coptic Orthodox community, which separated from
3105-408: A whole dam itself, that dam also would be held in place by gravity, i.e., there is no tension in the upstream face of the dam holding the top of the dam down. The designer does this because it is usually more practical to make a dam of material essentially just piled up than to make the material stick together against vertical tension. The shape that prevents tension in the upstream face also eliminates
3240-456: Is another Coptic name for Cairo, although others think that it is rather a name for the Abbasid province capital al-Askar . Ⲕⲁϩⲓⲣⲏ ( Kahi•ree ) is a popular modern rendering of an Arabic name (others being Ⲕⲁⲓⲣⲟⲛ [Kairon] and Ⲕⲁϩⲓⲣⲁ [Kahira]) which is modern folk etymology meaning 'land of sun'. Some argue that it was the name of an Egyptian settlement upon which Cairo was built, but it
3375-517: Is attested in the modern Coptic text Ⲡⲓⲫⲓⲣⲓ ⲛ̀ⲧⲉ ϯⲁⲅⲓⲁ ⲙ̀ⲙⲏⲓ Ⲃⲉⲣⲏⲛⲁ (The Tale of Saint Verina ). Lioui ( Ⲗⲓⲟⲩⲓ Late Coptic: [lɪˈjuːj] ) or Elioui ( Ⲉⲗⲓⲟⲩⲓ Late Coptic: [ælˈjuːj] ) is another name which is descended from the Greek name of Heliopolis ( Ήλιούπολις ). Some argue that Mistram ( Ⲙⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈmɪs.təɾɑm] ) or Nistram ( Ⲛⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈnɪs.təɾɑm] )
3510-424: Is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected. Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards
3645-820: Is derived from the Arabic al-Qāhirah ( القاهرة ), meaning 'the Vanquisher' or 'the Conqueror', given by the Fatimid Caliph al-Mu'izz following the establishment of the city as the capital of the Fatimid dynasty. Its full, formal name was al-Qāhirah al-Mu'izziyyah (القاهرة المعزيّة), meaning 'the Vanquisher of al-Mu'izz'. It is also supposedly due to the fact that the planet Mars , known in Arabic by names such as an-Najm al-Qāhir ( النجم القاهر , 'the Conquering Star'),
3780-437: Is dominated by wide boulevards, open spaces, and modern architecture of European influence, the eastern half, having grown haphazardly over the centuries, is dominated by small lanes, crowded tenements, and Islamic architecture . Northern and extreme eastern parts of Cairo, which include satellite towns , are among the most recent additions to the city, as they developed in the late-20th and early-21st centuries to accommodate
3915-555: Is either a calque meaning 'man breaker' ( Ϯ- , 'the', ⲕⲁϣ- , 'to break', and ⲣⲱⲙⲓ , 'man'), akin to Arabic al-Qāhirah , or a derivation from Arabic قَصْر الرُوم ( qaṣr ar-rūm , "the Roman castle"), another name of Babylon Fortress in Old Cairo . The Arabic name is also calqued as ⲧⲡⲟⲗⲓⲥ ϯⲣⲉϥϭⲣⲟ , "the victor city" in the Coptic antiphonary. The form Khairon ( Coptic : ⲭⲁⲓⲣⲟⲛ )
4050-536: Is informally referred to as Cairo by people from Alexandria ( IPA: [ˈkæjɾo] ; Egyptian Arabic : كايرو ). The area around present-day Cairo had long been a focal point of Ancient Egypt due to its strategic location at the junction of the Nile Valley and the Nile Delta regions (roughly Upper Egypt and Lower Egypt ), which also placed it at the crossing of major routes between North Africa and
4185-463: Is rather doubtful as this name is not attested in any Hieroglyphic or Demotic source, although some researchers, like Paul Casanova, view it as a legitimate theory. Cairo is also referred to as Ⲭⲏⲙⲓ ( Late Coptic: [ˈkɪ.mi] ) or Ⲅⲩⲡⲧⲟⲥ ( Late Coptic: [ˈɡɪp.dos] ), which means Egypt in Coptic, the same way it is referred to in Egyptian Arabic. Sometimes the city
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4320-471: Is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. The safety of an arch dam
4455-400: Is sparse and only happens in the colder months, but sudden showers can cause severe flooding. The summer months have high humidity due to its coastal location. Snowfall is extremely rare; a small amount of graupel , widely believed to be snow , fell on Cairo's easternmost suburbs on 13 December 2013, the first time Cairo's area received this kind of precipitation in many decades. Dew points in
4590-399: Is the more widely used of the two, though the hollow dam is frequently more economical to construct. Grand Coulee Dam is a solid gravity dam and Braddock Locks & Dam is a hollow gravity dam. A gravity dam can be combined with an arch dam into an arch-gravity dam for areas with massive amounts of water flow but less material available for a pure gravity dam. The inward compression of
4725-576: Is the thinnest arch dam in the world and one of the oldest arch dams in Asia. It was constructed some 700 years ago in Tabas county , South Khorasan Province , Iran . It stands 60 meters tall, and in crest is a one meter width. Some historians believe the dam was built by Shāh Abbās I, whereas others believe that he repaired it. In the Netherlands , a low-lying country, dams were often built to block rivers to regulate
4860-609: The Arab League has had its headquarters in Cairo for most of its existence. Cairo, like many other megacities , suffers from high levels of pollution and traffic. The Cairo Metro , opened in 1987, is the oldest metro system in Africa, and ranks amongst the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy 's 2010 Global Cities Index . The name of Cairo
4995-512: The Balkans . Cairene merchants were instrumental in bringing goods to the barren Hejaz , especially during the annual hajj to Mecca . It was during this same period that al-Azhar University reached the predominance among Islamic schools that it continues to hold today; pilgrims on their way to hajj often attested to the superiority of the institution, which had become associated with Egypt's body of Islamic scholars . The first printing press of
5130-611: The Belgian industrialist Édouard Empain and his Egyptian counterpart Boghos Nubar , built a suburb called Heliopolis (city of the sun in Greek) ten kilometers from the center of Cairo. In 1905–1907 the northern part of the Gezira island was developed by the Baehler Company into Zamalek , which would later become Cairo's upscale "chic" neighbourhood. In 1906 construction began on Garden City,
5265-576: The British invasion in 1882. The city's economic centre quickly moved west toward the Nile , away from the historic Islamic Cairo section and toward the contemporary, European-style areas built by Isma'il. Europeans accounted for five percent of Cairo's population at the end of the 19th century, by which point they held most top governmental positions. In 1906 the Heliopolis Oasis Company headed by
5400-588: The Fayum Depression to the Nile in Middle Egypt. Two dams called Ha-Uar running east–west were built to retain water during the annual flood and then release it to surrounding lands. The lake called Mer-wer or Lake Moeris covered 1,700 km (660 sq mi) and is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system in Dholavira in modern-day India
5535-561: The Harbaqa Dam , both in Roman Syria . The highest Roman dam was the Subiaco Dam near Rome ; its record height of 50 m (160 ft) remained unsurpassed until its accidental destruction in 1305. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of
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5670-471: The Khalij , continued to be a major feature of Cairo's geography and of its water supply until the 19th century. In 861, on the orders of the Abbasid caliph al-Mutawakkil , a Nilometer was built on Roda Island near Fustat. Although it was repaired and given a new roof in later centuries, its basic structure is still preserved today, making it the oldest preserved Islamic-era structure in Cairo today. In 868
5805-537: The Late Middle Ages , it could not escape the Black Death, which struck the city more than fifty times between 1348 and 1517. During its initial, and most deadly waves, approximately 200,000 people were killed by the plague, and, by the 15th century, Cairo's population had been reduced to between 150,000 and 300,000. The population decline was accompanied by a period of political instability between 1348 and 1412. It
5940-700: The Levant . Memphis , the capital of Egypt during the Old Kingdom and a major city up until the Ptolemaic period , was located a short distance south west of present-day Cairo. Heliopolis , another important city and major religious center, was located in what are now the modern districts of Matariya and Ain Shams in northeastern Cairo. It was largely destroyed by the Persian invasions in 525 BC and 343 BC and partly abandoned by
6075-500: The Mamluks and Ottomans further contributed to expansion on the east bank of the river. Because of the Nile's movement, the newer parts of the city— Garden City , Downtown Cairo , and Zamalek—are located closest to the riverbank. The areas, which are home to most of Cairo's embassies , are surrounded on the north, east, and south by the older parts of the city. Old Cairo , located south of
6210-513: The Mamluks , partly with the help of al-Salih's wife, Shajar ad-Durr , who ruled for a brief period around this time. Mamluks were soldiers who were purchased as young slaves and raised to serve in the sultan's army. Between 1250 and 1517 the throne of the Mamluk Sultanate passed from one mamluk to another in a system of succession that was generally non-hereditary, but also frequently violent and chaotic. The Mamluk Empire nonetheless became
6345-607: The Muslim conquest of Egypt in 641 next to an existing ancient Roman fortress, Babylon . Cairo was founded by the Fatimid dynasty in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods (12th–16th centuries). Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand minarets " for its preponderance of Islamic architecture . Cairo's historic center
6480-557: The National Inventory of Dams (NID). Cairo Cairo ( / ˈ k aɪ r oʊ / KY -roh ; Arabic : القاهرة , romanized : al-Qāhirah , Egyptian Arabic pronunciation: [el.qɑ(ː)ˈheɾɑ] ) is the capital and largest city of Egypt and the Cairo Governorate , being home to more than 10 million people. It is also part of the largest urban agglomeration in Africa ,
6615-461: The Shi'a Isma'ili Fatimid empire conquered Egypt after ruling from Ifriqiya. The Fatimid general Jawhar Al Saqili founded a new fortified city northeast of Fustat and of former al-Qata'i. It took four years to build the city, initially known as al-Manṣūriyyah, which was to serve as the new capital of the caliphate. During that time, the construction of the al-Azhar Mosque was commissioned by order of
6750-540: The Tunisian revolution that resulted in the overthrow of the long-time Tunisian president Zine El Abidine Ben Ali . On 11 February, following weeks of determined popular protest and pressure, Hosni Mubarak resigned from office. Under the rule of President el-Sisi , in March 2015 plans were announced for another yet-unnamed planned city to be built further east of the existing satellite city of New Cairo , intended to serve as
6885-645: The University of Oxford published a study of the cost of large dams – based on the largest existing dataset – documenting significant cost overruns for a majority of dams and questioning whether benefits typically offset costs for such dams. Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers . Man-made dams are typically classified according to their size (height), intended purpose or structure. Based on structure and material used, dams are classified as easily created without materials, arch-gravity dams , embankment dams or masonry dams , with several subtypes. In
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#17330861382477020-561: The new capital of Egypt . Cairo is located in northern Egypt , known as Lower Egypt , 165 km (100 mi) south of the Mediterranean Sea and 120 km (75 mi) west of the Gulf of Suez and Suez Canal . The city lies along the Nile River , immediately south of the point where the river leaves its desert-bound valley and branches into the low-lying Nile Delta region. Although
7155-467: The "Faruq edition" in honour of then ruler, King Faruq . British troops remained in the country until 1956. During this time, urban Cairo, spurred by new bridges and transport links, continued to expand to include the upscale neighbourhoods of Garden City, Zamalek, and Heliopolis. Between 1882 and 1937, the population of Cairo more than tripled—from 347,000 to 1.3 million —and its area increased from 10 to 163 km (4 to 63 sq mi). The city
7290-558: The 15th and 13th centuries BC. The Kallanai Dam in South India, built in the 2nd century AD, is one of the oldest water regulating structures still in use. Roman engineers built dams with advanced techniques and materials, such as hydraulic mortar and Roman concrete, which allowed for larger structures. They introduced reservoir dams, arch-gravity dams, arch dams, buttress dams, and multiple arch buttress dams. In Iran, bridge dams were used for hydropower and water-raising mechanisms. During
7425-405: The 20th century Cairo continue to grow enormously in both population and area. Between 1947 and 2006 the population of Greater Cairo went from 2,986,280 to 16,292,269. The population explosion also drove the rise of "informal" housing ( 'ashwa'iyyat ), meaning housing that was built without any official planning or control. The exact form of this type of housing varies considerably but usually has
7560-451: The Albanians, and the long-weakened Mamluks jostling for control of the country. Continued civil war allowed an Albanian named Muhammad Ali Pasha to ascend to the role of commander and eventually, with the approval of the religious establishment , viceroy of Egypt in 1805. Until his death in 1848, Muhammad Ali Pasha instituted a number of social and economic reforms that earned him
7695-497: The Arab world and the Middle East . The Greater Cairo metropolitan area is the 12th-largest in the world by population with over 22.1 million people. Cairo is associated with ancient Egypt , as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta , the city first developed as Fustat following
7830-535: The British began construction in 1898. The project was designed by Sir William Willcocks and involved several eminent engineers of the time, including Sir Benjamin Baker and Sir John Aird , whose firm, John Aird & Co. , was the main contractor. Capital and financing were furnished by Ernest Cassel . When initially constructed between 1899 and 1902, nothing of its scale had ever before been attempted; on completion, it
7965-401: The Cairo metropolis extends away from the Nile in all directions, the city of Cairo resides only on the east bank of the river and two islands within it on a total area of 453 km (175 sq mi). Geologically, Cairo lies on alluvium and sand dunes which date from the quaternary period. Until the mid-19th century, when the river was tamed by dams, levees, and other controls,
8100-590: The Citadel, Saladin also began the construction of a new 20-kilometre-long wall that would protect both Cairo and Fustat on their eastern side and connect them with the new Citadel. These construction projects continued beyond Saladin's lifetime and were completed under his Ayyubid successors. In 1250, during the Seventh Crusade , the Ayyubid dynasty had a crisis with the death of al-Salih and power transitioned instead to
8235-509: The Colorado River is a constant-angle arch dam. A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada , in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with
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#17330861382478370-403: The Colorado River. By 1997, there were an estimated 800,000 dams worldwide, with some 40,000 of them over 15 meters high. Early dam building took place in Mesopotamia and the Middle East . Dams were used to control water levels, for Mesopotamia's weather affected the Tigris and Euphrates Rivers. The earliest known dam is the Jawa Dam in Jordan , 100 kilometres (62 mi) northeast of
8505-415: The Middle Ages, dams were built in the Netherlands to regulate water levels and prevent sea intrusion. In the 19th century, large-scale arch dams were constructed around the British Empire, marking advances in dam engineering techniques. The era of large dams began with the construction of the Aswan Low Dam in Egypt in 1902. The Hoover Dam, a massive concrete arch-gravity dam, was built between 1931 and 1936 on
8640-445: The Middle East for water control. The earliest known dam is the Jawa Dam in Jordan , dating to 3,000 BC. Egyptians also built dams, such as Sadd-el-Kafara Dam for flood control. In modern-day India, Dholavira had an intricate water-management system with 16 reservoirs and dams. The Great Dam of Marib in Yemen, built between 1750 and 1700 BC, was an engineering wonder, and Eflatun Pinar, a Hittite dam and spring temple in Turkey, dates to
8775-404: The Middle East, printing in Hebrew , was established in Cairo c. 1557 by a scion of the Soncino family of printers, Italian Jews of Ashkenazi origin who operated a press in Constantinople. The existence of the press is known solely from two fragments discovered in the Cairo Geniza . Under the Ottomans, Cairo expanded south and west from its nucleus around the Citadel. The city
8910-399: The Nile Corniche , and improved the city's network of bridges and highways. Meanwhile, additional controls of the Nile fostered development within Gezira Island and along the city's waterfront. The metropolis began to encroach on the fertile Nile Delta , prompting the government to build desert satellite towns and devise incentives for city-dwellers to move to them. In the second half of
9045-417: The Nile in the vicinity of Cairo was highly susceptible to changes in course and surface level. Over the years, the Nile gradually shifted westward, providing the site between the eastern edge of the river and the Mokattam highlands on which the city now stands. The land on which Cairo was established in 969 (present-day Islamic Cairo ) was located underwater just over three hundred years earlier, when Fustat
9180-414: The Roman and Byzantine churches in the late 4th century. Cairo's oldest extant churches, such as the Church of Saint Barbara and the Church of Saints Sergius and Bacchus (from the late 7th or early 8th century), are located inside the fortress walls in what is now known as Old Cairo or Coptic Cairo . The Muslim conquest of Byzantine Egypt was led by Amr ibn al-As from 639 to 642. Babylon Fortress
9315-437: The United States alone, there are approximately 2,000,000 or more "small" dams that are not included in the Army Corps of Engineers National Inventory of dams . Records of small dams are kept by state regulatory agencies and therefore information about small dams is dispersed and uneven in geographic coverage. Countries worldwide consider small hydropower plants (SHPs) important for their energy strategies, and there has been
9450-457: The World Commission on Dams also includes in the "large" category, dams which are between 5 and 15 m (16 and 49 ft) high with a reservoir capacity of more than 3 million cubic metres (2,400 acre⋅ft ). Hydropower dams can be classified as either "high-head" (greater than 30 m in height) or "low-head" (less than 30 m in height). As of 2021 , ICOLD's World Register of Dams contains 58,700 large dam records. The tallest dam in
9585-403: The arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. When the upstream face
9720-403: The area now composing Downtown Cairo , came to fruition. Isma'il also sought to modernize the city, which was merging with neighbouring settlements, by establishing a public works ministry, bringing gas and lighting to the city, and opening a theatre and opera house. The immense debt resulting from Isma'il's projects provided a pretext for increasing European control, which culminated with
9855-651: The back of the dam through a large pipe to drive a water wheel and watermill . In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m (3,000 ft) long, and that it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir Dam, provided irrigation for 300 villages. Shāh Abbās Arch (Persian: طاق شاه عباس), also known as Kurit Dam ,
9990-487: The bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam , in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept constant and the variation in distance between the abutments at various levels is taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam on
10125-402: The buttress loads are heavy. In a gravity dam, the force that holds the dam in place against the push from the water is Earth's gravity pulling down on the mass of the dam. The water presses laterally (downstream) on the dam, tending to overturn the dam by rotating about its toe (a point at the bottom downstream side of the dam). The dam's weight counteracts that force, tending to rotate the dam
10260-500: The caliph, which developed into the third-oldest university in the world. Cairo would eventually become a centre of learning, with the library of Cairo containing hundreds of thousands of books. When Caliph al-Mu'izz li Din Allah arrived from the old Fatimid capital of Mahdia in Tunisia in 973, he gave the city its present name, Qāhirat al-Mu'izz ("The Vanquisher of al-Mu'izz"), from which
10395-497: The capital Amman . This gravity dam featured an originally 9-metre-high (30 ft) and 1 m-wide (3.3 ft) stone wall, supported by a 50 m-wide (160 ft) earthen rampart. The structure is dated to 3000 BC. However, the oldest continuously operational dam is Lake Homs Dam , built in Syria between 1319-1304 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, about 25 km (16 mi) south of Cairo ,
10530-569: The capital of the caliphate in Arabia . Ibn al-As also founded a mosque for the city at the same time, now known as the Mosque of Amr Ibn al-As , the oldest mosque in Egypt and Africa (although the current structure dates from later expansions). In 750, following the overthrow of the Umayyad caliphate by the Abbasids , the new rulers created their own settlement to the northeast of Fustat which became
10665-512: The center of the city, next to the palace. After his death in 884, Ibn Tulun was succeeded by his son and his descendants who continued a short-lived dynasty, the Tulunids . In 905, the Abbasids sent general Muhammad Sulayman al-Katib to re-assert direct control over the country. Tulunid rule was ended and al-Qatta'i was razed to the ground, except for the mosque which remains standing today. In 969,
10800-417: The centre, holds the remnants of Fustat and the heart of Egypt's Coptic Christian community, Coptic Cairo . The Boulaq district, which lies in the northern part of the city, was born out of a major 16th-century port and is now a major industrial centre. The Citadel is located east of the city centre around Islamic Cairo , which dates back to the Fatimid era and the foundation of Cairo. While western Cairo
10935-642: The city walls in stone and constructed the city gates of Bab al-Futuh , Bab al-Nasr , and Bab Zuweila that still stand today. During the Fatimid period Fustat reached its apogee in size and prosperity, acting as a center of craftsmanship and international trade and as the area's main port on the Nile. Historical sources report that multi-story communal residences existed in the city, particularly in its center, which were typically inhabited by middle and lower-class residents. Some of these were as high as seven stories and could house some 200 to 350 people. They may have been similar to Roman insulae and may have been
11070-639: The city's infrastructure and cleanliness. Its economy and politics also became more deeply connected with the wider Mediterranean. Some Mamluk sultans in this period, such as Barbsay (r. 1422–1438) and Qaytbay (r. 1468–1496), had relatively long and successful reigns. After al-Nasir Muhammad, Qaytbay was one of the most prolific patrons of art and architecture of the Mamluk era. He built or restored numerous monuments in Cairo, in addition to commissioning projects beyond Egypt. The crisis of Mamluk power and of Cairo's economic role deepened after Qaytbay. The city's status
11205-581: The city's rapid growth. The western bank of the Nile is commonly included within the urban area of Cairo, but it composes the city of Giza and the Giza Governorate . Giza city has also undergone significant expansion over recent years, and today has a population of 2.7 million. The Cairo Governorate was just north of the Helwan Governorate from 2008 when some Cairo's southern districts, including Maadi and New Cairo , were split off and annexed into
11340-460: The city, from March to May and the air often becomes uncomfortably dry. Winters are mild to warm, while summers are long and hot. High temperatures in winter range from 14 to 22 °C (57 to 72 °F), while night-time lows drop to below 11 °C (52 °F), often to 5 °C (41 °F). In summer, the highs often exceed 31 °C (88 °F) but rarely surpass 40 °C (104 °F), and lows drop to about 20 °C (68 °F). Rainfall
11475-626: The city. The masonry arch dam wall was designed by Lieutenant Percy Simpson who was influenced by the advances in dam engineering techniques made by the Royal Engineers in India . The dam cost £17,000 and was completed in 1856 as the first engineered dam built in Australia, and the second arch dam in the world built to mathematical specifications. The first such dam was opened two years earlier in France . It
11610-647: The construction of the Rideau Canal in Canada near modern-day Ottawa and built a series of curved masonry dams as part of the waterway system. In particular, the Jones Falls Dam , built by John Redpath , was completed in 1832 as the largest dam in North America and an engineering marvel. In order to keep the water in control during construction, two sluices , artificial channels for conducting water, were kept open in
11745-469: The dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitational force required by the dam is lessened, i.e., the dam does not need to be so massive. This enables thinner dams and saves resources. A barrage dam is a special kind of dam that consists of a line of large gates that can be opened or closed to control the amount of water passing the dam. The gates are set between flanking piers which are responsible for supporting
11880-533: The dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule. By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m (49 ft) high. In 2014, scholars from
12015-605: The dam. If large enough uplift pressures are generated there is a risk of destabilizing the concrete gravity dam. On a suitable site, a gravity dam can prove to be a better alternative to other types of dams. When built on a solid foundation, the gravity dam probably represents the best-developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are built in some instances where an arch dam would have been more economical. Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. The solid form
12150-407: The dam. The first was near the base of the dam on its east side. A second sluice was put in on the west side of the dam, about 20 ft (6.1 m) above the base. To make the switch from the lower to upper sluice, the outlet of Sand Lake was blocked off. Hunts Creek near the city of Parramatta , Australia , was dammed in the 1850s, to cater to the demand for water from the growing population of
12285-450: The dams' potential range and magnitude of environmental disturbances. The International Commission on Large Dams (ICOLD) defines a "large dam" as "A dam with a height of 15 m (49 ft) or greater from lowest foundation to crest or a dam between 5 m (16 ft) metres and 15 metres impounding more than 3 million cubic metres (2,400 acre⋅ft )". "Major dams" are over 150 m (490 ft) in height. The Report of
12420-441: The development of new planned cities on the outskirts of Cairo, generally established on desert land. These new satellite cities were intended to provide housing, investment, and employment opportunities for the region's growing population as well as to pre-empt the further growth of informal neighbourhoods. As of 2014, about 10% of the population of Greater Cairo lived in the new cities. Concurrently, Cairo established itself as
12555-543: The entrance of a canal connecting the Nile to the Red Sea that was created earlier by emperor Trajan (r. 98–117). Further north of the fortress, near the present-day district of al-Azbakiya , was a port and fortified outpost known as Tendunyas ( Coptic : ϯⲁⲛⲧⲱⲛⲓⲁⲥ ) or Umm Dunayn. While no structures older than the 7th century have been preserved in the area aside from the Roman fortifications, historical evidence suggests that
12690-743: The family of the last Fatimid caliph, al-'Āḍid . As the first Sultan of Egypt , Saladin established the Ayyubid dynasty , based in Cairo, and aligned Egypt with the Sunni Abbasids, who were based in Baghdad . In 1176, Saladin began construction on the Cairo Citadel , which was to serve as the seat of the Egyptian government until the mid-19th century. The construction of the Citadel definitively ended Fatimid-built Cairo's status as an exclusive palace-city and opened it up to common Egyptians and to foreign merchants, spurring its commercial development. Along with
12825-549: The first large-scale arch dams. Three pioneering arch dams were built around the British Empire in the early 19th century. Henry Russel of the Royal Engineers oversaw the construction of the Mir Alam dam in 1804 to supply water to the city of Hyderabad (it is still in use today). It had a height of 12 m (39 ft) and consisted of 21 arches of variable span. In the 1820s and 30s, Lieutenant-Colonel John By supervised
12960-662: The first was the Roman-built dam bridge in Dezful , which could raise water 50 cubits (c. 23 m) to supply the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti . The first was built at Shustar on the River Karun , Iran, and many of these were later built in other parts of the Islamic world . Water was conducted from
13095-437: The flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation , human consumption , industrial use , aquaculture , and navigability . Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve
13230-534: The force of water. A fixed-crest dam is a concrete barrier across a river. Fixed-crest dams are designed to maintain depth in the channel for navigation. They pose risks to boaters who may travel over them, as they are hard to spot from the water and create induced currents that are difficult to escape. There is variability, both worldwide and within individual countries, such as in the United States, in how dams of different sizes are categorized. Dam size influences construction, repair, and removal costs and affects
13365-498: The genesis of present-day Cairo to the foundation of Fustat. The choice of founding a new settlement at this inland location, instead of using the existing capital of Alexandria on the Mediterranean coast, may have been due to the new conquerors' strategic priorities. One of the first projects of the new Muslim administration was to clear and re-open Trajan's ancient canal in order to ship grain more directly from Egypt to Medina ,
13500-457: The late first century BC. However, the origins of modern Cairo are generally traced back to a series of settlements in the first millennium AD. Around the turn of the fourth century, as Memphis was continuing to decline in importance, the Romans established a large fortress along the east bank of the Nile . The fortress, called Babylon , was built by the Roman emperor Diocletian (r. 285–305) at
13635-625: The main stream of the Kaveri River in Tamil Nadu , South India . The basic structure dates to the 2nd century AD and is considered one of the oldest water diversion or water regulating structures still in use. The purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included
13770-441: The name "Cairo" ( al-Qāhira ) originates. The caliphs lived in a vast and lavish palace complex that occupied the heart of the city. Cairo remained a relatively exclusive royal city for most of this era, but during the tenure of Badr al-Gamali as vizier (1073–1094) the restrictions were loosened for the first time and richer families from Fustat were allowed to move into the city. Between 1087 and 1092 Badr al-Gamali also rebuilt
13905-755: The new governorate, to 2011 when the Helwan Governorate was reincorporated into the Cairo Governorate. According to the World Health Organization , the level of air pollution in Cairo is nearly 12 times higher than the recommended safety level. In Cairo, and along the Nile River Valley, the climate is a hot desert climate ( BWh according to the Köppen climate classification system ). Wind storms can be frequent, bringing Saharan dust into
14040-415: The new provincial capital. This was known as al-Askar ( Arabic : العسكر , lit. 'the camp') as it was laid out like a military camp. A governor's residence and a new mosque were also added, with the latter completed in 786. The Red Sea canal re-excavated in the 7th century was closed by the Abbasid caliph al-Mansur in al-Mansur ( r. 754–775 ), but a part of the canal, known as
14175-668: The other basic dam designs which had been unknown until then. These include arch-gravity dams , arch dams , buttress dams and multiple arch buttress dams , all of which were known and employed by the 2nd century AD (see List of Roman dams ). Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran. In Iran , bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels , which often powered water-raising mechanisms. One of
14310-429: The other way about its toe. The designer ensures that the dam is heavy enough that the dam's weight wins that contest. In engineering terms, that is true whenever the resultant of the forces of gravity acting on the dam and water pressure on the dam acts in a line that passes upstream of the toe of the dam. The designer tries to shape the dam so if one were to consider the part of the dam above any particular height to be
14445-463: The primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes ) are used to manage or prevent water flow into specific land regions. The word dam can be traced back to Middle English , and before that, from Middle Dutch , as seen in the names of many old cities, such as Amsterdam and Rotterdam . Ancient dams were built in Mesopotamia and
14580-537: The principles behind dam design. In France, J. Augustin Tortene de Sazilly explained the mechanics of vertically faced masonry gravity dams, and Zola's dam was the first to be built on the basis of these principles. The era of large dams was initiated with the construction of the Aswan Low Dam in Egypt in 1902, a gravity masonry buttress dam on the Nile River . Following their 1882 invasion and occupation of Egypt ,
14715-475: The prototypes for the rental apartment complexes which became common in the later Mamluk and Ottoman periods. However, in 1168 the Fatimid vizier Shawar set fire to unfortified Fustat to prevent its potential capture by Amalric , the Crusader king of Jerusalem . While the fire did not destroy the city and it continued to exist afterward, it did mark the beginning of its decline. Over the following centuries it
14850-408: The reign of the Mamluk sultan al-Nasir Muhammad (1293–1341, with interregnums ), Cairo reached its apogee in terms of population and wealth. By 1340, Cairo had a population of close to half a million, making it the largest city west of China . Multi-story buildings occupied by rental apartments, known as a rab' (plural ribā' or urbu ), became common in the Mamluk period and continued to be
14985-579: The standard for modern printings of the Quran for much of the Islamic world. The publication has been called a "terrific success", and the edition has been described as one "now widely seen as the official text of the Qur'an", so popular among both Sunni and Shi'a that the common belief among less well-informed Muslims is "that the Qur'an has a single, unambiguous reading". Minor amendments were made later in 1924 and in 1936 -
15120-487: The state of New Mexico defines a jurisdictional dam as 25 feet or greater in height and storing more than 15 acre-feet or a dam that stores 50 acre-feet or greater and is six feet or more in height (section 72-5-32 NMSA), suggesting that dams that do not meet these requirements are non-jurisdictional. Most US dams, 2.41 million of a total of 2.5 million dams, are not under the jurisdiction of any public agency (i.e., they are non-jurisdictional), nor are they listed on
15255-465: The title of founder of modern Egypt. However, while Muhammad Ali initiated the construction of public buildings in the city, those reforms had minimal effect on Cairo's landscape. Bigger changes came to Cairo under Isma'il Pasha (r. 1863–1879), who continued the modernisation processes started by his grandfather. Drawing inspiration from Paris , Isma'il envisioned a city of maidans and wide avenues; due to financial constraints, only some of them, in
15390-406: The water level and to prevent the sea from entering the marshlands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often influenced Dutch place names. The present Dutch capital, Amsterdam (old name Amstelredam ), started with a dam on the river Amstel in the late 12th century, and Rotterdam began with a dam on the river Rotte ,
15525-634: The water load, and are often used to control and stabilize water flow for irrigation systems. An example of this type of dam is the now-decommissioned Red Bluff Diversion Dam on the Sacramento River near Red Bluff, California . Barrages that are built at the mouths of rivers or lagoons to prevent tidal incursions or use the tidal flow for tidal power are known as tidal barrages . Embankment dams are made of compacted earth, and are of two main types: rock-fill and earth-fill. Like concrete gravity dams, embankment dams rely on their weight to hold back
15660-577: The world is the 305 m-high (1,001 ft) Jinping-I Dam in China . As with large dams, small dams have multiple uses, such as, but not limited to, hydropower production, flood protection, and water storage. Small dams can be particularly useful on farms to capture runoff for later use, for example, during the dry season. Small scale dams have the potential to generate benefits without displacing people as well, and small, decentralised hydroelectric dams can aid rural development in developing countries. In
15795-532: Was 102 m (335 ft) long at its base and 87 m (285 ft) wide. The structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III , and Amenemhat IV dug a canal 16 km (9.9 mi) long linking
15930-594: Was Cairo, the former palace-city, that became the new economic center and attracted migration from Fustat. While the Crusaders did not capture the city in 1168, a continuing power struggle between Shawar, King Amalric, and the Zengid general Shirkuh led to the downfall of the Fatimid establishment. In 1169, Shirkuh's nephew Saladin was appointed as the new vizier of Egypt by the Fatimids and two years later he seized power from
16065-507: Was at the height of Mamluk—and Cairene—influence in the mid-14th century. The French occupation was short-lived as British and Ottoman forces, including a sizeable Albanian contingent, recaptured the country in 1801. Cairo itself was besieged by a British and Ottoman force culminating with the French surrender on 22 June 1801. The British vacated Egypt two years later, leaving the Ottomans,
16200-399: Was awarded World Heritage Site status in 1979. Cairo is considered a World City with a "Beta +" classification according to GaWC . Cairo has the oldest and largest film and music industry in the Arab world , as well as Egypt's oldest institution of higher learning, Al-Azhar University . Many international media, businesses, and organizations have regional headquarters in the city;
16335-565: Was besieged in September 640 and fell in April 641. In 641 or early 642, after the surrender of Alexandria (the Egyptian capital at the time), he founded a new settlement next to Babylon Fortress. The city, known as Fustat ( Arabic : الفسطاط , romanized : al-Fusṭāṭ , lit. 'the tent'), served as a garrison town and as the new administrative capital of Egypt. Historians such as Janet Abu-Lughod and André Raymond trace
16470-551: Was built. The system included 16 reservoirs, dams and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen . Initiated sometime between 1750 and 1700 BC, it was made of packed earth – triangular in cross-section, 580 m (1,900 ft) in length and originally 4 m (13 ft) high – running between two groups of rocks on either side, to which it
16605-539: Was devastated during the 1952 riots known as the Cairo Fire or Black Saturday, which saw the destruction of nearly 700 shops, movie theatres, casinos and hotels in downtown Cairo. The British departed Cairo following the Egyptian Revolution of 1952 , but the city's rapid growth showed no signs of abating. Seeking to accommodate the increasing population, President Gamal Abdel Nasser redeveloped Tahrir Square and
16740-497: Was diminished after Vasco da Gama discovered a sea route around the Cape of Good Hope between 1497 and 1499, thereby allowing spice traders to avoid Cairo. Cairo's political influence diminished significantly after the Ottomans defeated Sultan al-Ghuri in the Battle of Marj Dabiq in 1516 and conquered Egypt in 1517. Ruling from Constantinople , Sultan Selim I relegated Egypt to
16875-490: Was first built. Low periods of the Nile during the 11th century continued to add to the landscape of Cairo; a new island, known as Geziret al-Fil , first appeared in 1174, but eventually became connected to the mainland. Today, the site of Geziret al-Fil is occupied by the Shubra district. The low periods created another island at the turn of the 14th century that now composes Zamalek and Gezira . Land reclamation efforts by
17010-479: Was first published on 10 July 1924 in Cairo under the patronage of King Fuad . The goal of the government of the newly formed Kingdom of Egypt was not to delegitimize the other variant Quranic texts (" qira'at "), but to eliminate errors found in Qur'anic texts used in state schools. A committee of teachers chose to preserve a single one of the canonical qira'at "readings", namely that of the " Ḥafṣ " version, an 8th-century Kufic recitation . This edition has become
17145-483: Was linked by substantial stonework. Repairs were carried out during various periods, most importantly around 750 BC, and 250 years later the dam height was increased to 7 m (23 ft). After the end of the Kingdom of Saba , the dam fell under the control of the Ḥimyarites (c. 115 BC) who undertook further improvements, creating a structure 14 m (46 ft) high, with five spillways, two masonry-reinforced sluices,
17280-692: Was nonetheless in this period that the largest Mamluk-era religious monument, the Madrasa-Mosque of Sultan Hasan , was built. In the late 14th century, the Burji Mamluks replaced the Bahri Mamluks as rulers of the Mamluk state, but the Mamluk system continued to decline. Though the plagues returned frequently throughout the 15th century, Cairo remained a major metropolis and its population recovered in part through rural migration . More conscious efforts were conducted by rulers and city officials to redress
17415-404: Was possibly the world's first concrete arch dam. Designed by Henry Charles Stanley in 1880 with an overflow spillway and a special water outlet, it was eventually heightened to 10 m (33 ft). In the latter half of the nineteenth century, significant advances in the scientific theory of masonry dam design were made. This transformed dam design from an art based on empirical methodology to
17550-493: Was rising at the time of the city's founding. Egyptians often refer to Cairo as Maṣr ( IPA: [mɑsˤɾ] ; مَصر ), the Egyptian Arabic name for Egypt itself, emphasizing the city's importance for the country. There are a number of Coptic names for the city. Tikešrōmi ( Coptic : Ϯⲕⲉϣⲣⲱⲙⲓ Late Coptic: [di.kɑʃˈɾoːmi] ) is attested in the 1211 text The Martyrdom of John of Phanijoit and
17685-486: Was sold and replaced by newer buildings, becoming a prestigious site for the construction of Mamluk religious and funerary complexes. Construction projects initiated by the Mamluks pushed the city outward while also bringing new infrastructure to the centre of the city. Meanwhile, Cairo flourished as a centre of Islamic scholarship and a crossroads on the spice trade route among the civilisations in Afro-Eurasia . Under
17820-461: Was the first French arch dam of the industrial era , and it was built by François Zola in the municipality of Aix-en-Provence to improve the supply of water after the 1832 cholera outbreak devastated the area. After royal approval was granted in 1844, the dam was constructed over the following decade. Its construction was carried out on the basis of the mathematical results of scientific stress analysis. The 75-miles dam near Warwick , Australia,
17955-421: Was the focal point of the 2011 Egyptian revolution against former president Hosni Mubarak . More than 50,000 protesters first occupied the square on 25 January, during which the area's wireless services were reported to be impaired. In the following days Tahrir Square continued to be the primary destination for protests in Cairo. The uprising was mainly a campaign of non-violent civil resistance, which featured
18090-658: Was the largest masonry dam in the world. The Hoover Dam is a massive concrete arch-gravity dam , constructed in the Black Canyon of the Colorado River , on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression . In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power . The winning bid to build
18225-399: Was the second-largest in the empire, behind Constantinople, and, although migration was not the primary source of Cairo's growth, twenty percent of its population at the end of the 18th century consisted of religious minorities and foreigners from around the Mediterranean . Still, when Napoleon arrived in Cairo in 1798, the city's population was less than 300,000, forty percent lower than it
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