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Wadi Al-Garawi
Sadd el-Kafara ("Dam of the Infidels") was a masonry embankment dam on Wadi al-Garawi 10 km southeast of Helwan in Cairo, Egypt. The dam was built in the first half of the third millennium BC by the ancient Egyptians for flood control and is the second oldest dam of the world, after the Marib Dam in Yemen. Never completed, the dam was under construction for 10–12 years before being destroyed by a flood. It was rediscovered by Georg Schweinfurth in 1885. Specifications The dam was not finished but was about 111m long and 14m tall with a base width of 98m and crest width of 56m. The dam's core was 32m wide and consisted of 60,000 tons of earth and rock-fill. Surrounding the core were two loosely filled rubble and rock-fill layer-walls. The downstream wall was about 37m wide, the upstream wall about 29m wide and they encompassed of material. Encasing the dam were upstream and downstream walls created from limestone ashlars. The ashlars were set but not mortared in steppe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dams In Egypt
A dam is a barrier that stops or restricts 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 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 the Middle East for water control. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. Egyptians also built dam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jawa Dam (Jordan)
Jawa is the site of the oldest proto-urban development in Jordan, dating from the late 4th millennium BC (Early Bronze Age). It is located in one of the driest areas of the Black Desert (Harrat al-Shamah) of Eastern Jordan. Remains of dams have been found, the largest of which is a masonry gravity dam and the oldest known dam in the world. It was used as a protection from flash floods. Discovery and history of investigation Jawa was first reported by French explorer Antoine Poidebard, who flew over and photographed the site in 1931, mistaking it for Roman ruins. Before and after Poidebard's discovery, several archaeological expeditions came close to but missed the site. Nelson Glueck visited it in 1947 but apparently failed to notice its significance, describing Jawa as a "small, filthy spring '' ��' probably never more than a small police post." Finally, in 1950, an expedition led by epigrapher F. V. Winnett reached the site and documented some of the inscriptions there. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nile
The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the List of river systems by length, longest river in the world, though this has been contested by research suggesting that the Amazon River is slightly longer.Amazon Longer Than Nile River, Scientists Say Of the world's major rivers, the Nile has one of the lowest average annual flow rates. About long, its drainage basin covers eleven countries: the Democratic Republic of the Congo, Tanzania, Burundi, Rwanda, Uganda, Kenya, Ethiopia, Eritrea, South Sudan, Sudan, and Egypt. In pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spillway
A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that water does not damage parts of the structure not designed to convey water. Spillways can include floodgates and fuse plugs to regulate water flow and reservoir level. Such features enable a spillway to regulate downstream flow—by releasing water in a controlled manner before the reservoir is full, operators can prevent an unacceptably large release later. Other uses of the term "spillway" include bypasses of dams and outlets of channels used during high water, and outlet channels carved through natural dams such as moraines. Water normally flows over a spillway only during flood periods, when the reservoir has reached its capacity and water continues entering faster than it can be released. In contrast, an intake tower is a structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ashlar
Ashlar () is a cut and dressed rock (geology), stone, worked using a chisel to achieve a specific form, typically rectangular in shape. The term can also refer to a structure built from such stones. Ashlar is the finest stone masonry unit, and is generally rectangular (cuboid). It was described by Vitruvius as ''opus isodomum'' or trapezoidal. Precisely cut "on all faces adjacent to those of other stones", ashlar is capable of requiring only very thin joints between blocks, and the visible face of the stone may be Quarry-faced stone, quarry-faced or feature a variety of treatments: tooled, smoothly polished or rendered with another material for decorative effect. One such decorative treatment consists of small grooves achieved by the application of a metal comb. Generally used only on softer stone ashlar, this decoration is known as "mason's drag". Ashlar is in contrast to rubble masonry, which employs irregularly shaped stones, sometimes minimally worked or selected for simi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science), crystal forms of calcium carbonate . Limestone forms when these minerals Precipitation (chemistry), precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly Dolomite (rock), dolomite, a closely related rock, which contains a high percentage of the mineral Dolomite (mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georg August Schweinfurth
Georg August Schweinfurth (29 December 1836 – 19 September 1925) was a Baltic Germans, Baltic German botanist and ethnologist who explored East Central Africa. Life and explorations He was born at Riga, Latvia, then part of the Russian Empire. He was educated at the universities of Heidelberg, Munich and Berlin (1856–1862), where he particularly devoted himself to botany and palaeontology. Commissioned to arrange the collections brought from Sudan by Adalbert von Barnim and Robert Hartmann (naturalist), Robert Hartmann, his attention was directed to that region; and in 1863, he travelled round the shores of the Red Sea, repeatedly traversed the district between that sea and the Nile, passed on to Khartoum, and returned to Europe in 1866. In 1866, botanist A.Braun published ''Schweinfurthia (plant), Schweinfurthia'' which is a genus of flowering plants from Africa and Asia, belonging to the family Plantaginaceae and named in Georg August Schweinfurth's honour. His resear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood Control
Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Flood management methods can be either of the ''structural'' type (i.e. flood control) and of the ''non-structural'' type. Structural methods hold back floodwaters physically, while non-structural methods do not. Building hard infrastructure to prevent flooding, such as flood walls, is effective at managing flooding. However, it is best practice within landscape engineering to rely more on soft infrastructure and Nature-based solutions, natural systems, such as marshes and Floodplain, flood plains, for handling the increase in water. Flood management can include ''flood risk management,'' which focuses on measures to reduce risk, vulnerability and exposure to flood disasters and providing risk analysis through, for example, flood ris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helwan
Helwan ( ', , ) is a suburban district in the Southern Area of Cairo, Egypt. The area of Helwan witnessed prehistoric, ancient Egyptian, Roman and Muslim era activity. More recently it was designated as a city until as late as the 1960s, before it became contiguous with the city of Cairo and was incorporated as a district. For a brief period between April 2008 and April 2011 it was redesignated as a city, and served as the capital of the now defunct Helwan Governorate that was split from Cairo and Giza governorates, before being re-incorporated back into them. The ''kism'' of Helwan had a population of 521,239 in the 2017 census. History The Helwan and Isnian cultures of the late Epipalaeolithic, and their Ouchata retouch methods for creating microlithic tools may have contributed to the development of the Harifian cultural assemblage of the Sinai, which may have introduced Proto-Semitic language Proto-Semitic is the Linguistic reconstruction, reconstructed common ance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Egypt
Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower Egypt were amalgamated by Menes, who is believed by the majority of List of Egyptologists, Egyptologists to have been the same person as Narmer. The history of ancient Egypt unfolded as a series of stable kingdoms interspersed by the "Periodization of ancient Egypt, Intermediate Periods" of relative instability. These stable kingdoms existed in one of three periods: the Old Kingdom of Egypt, Old Kingdom of the Early Bronze Age; the Middle Kingdom of Egypt, Middle Kingdom of the Middle Bronze Age; or the New Kingdom of Egypt, New Kingdom of the Late Bronze Age. The pinnacle of ancient Egyptian power was achieved during the New Kingdom, which extended its rule to much of Nubia and a considerable portion of the Levant. After this period, Egypt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
