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Wadi
Wadi ( ; ) is a river valley or a wet (ephemerality, ephemeral) Stream bed, riverbed that contains water only when heavy rain occurs. Wadis are located on gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of alluvial fans and extend to inland sabkhas or dry lakes. Permanent channels do not exist, due to lack of continual water flow. Water percolates down into the stream bed, causing an abrupt loss of energy and resulting in vast deposition. Wadis may develop dams of sediment that change the stream patterns in the next flash flood. Wadis tend to be associated with centers of human population because sub-surface water is sometimes available in them. Nomadic and pastoral desert peoples will rely on seasonal vegetation found in wadis, even in regions as dry as the Sahara, as they travel in complex transhumance routes. The centrality of wadis to water – and human life – in desert environments gave birth to the distinct sub-field of wadi h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wadi Dawan
Wadi Dawan () is a desert valley located in the Hadhramaut Governorate of central Yemen. It is a significant tributary of the larger Wadi Hadhramaut and features narrow canyons and clustered villages with towering mud-built houses. It is noted for its mudbrick architecture and honey production. Modern history On January 18, 2008, an ambush attack on Belgian tourists traveling in a convoy through the valley took place. A convoy of four jeeps carrying 15 tourists to Shibam was ambushed by gunmen in a hidden pickup truck. Two Belgian women, Claudine Van Caillie, of Bruges, 63, and Katrine Glorie, from East Flanders, 54, as well as two Yemenis, a driver and a guide, were killed; another man was also heavily wounded, several others suffered minor wounds.Deux Belges tuées au Y� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Arctic. The name "Sahara" is derived from , a broken plural form of ( ), meaning "desert". The desert covers much of North Africa, excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb, and the Nile, Nile Valley in Egypt and the Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the Sahel, a belt of Tropical and subtropical grasslands, savannas, and shrublands, semi-arid tropical savanna around the Niger River valley and the Sudan (region), Sudan region of sub-Saharan Africa. The Sahara can be divided into several regions, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arroyo (watercourse)
An arroyo ( (from Spanish Language, Spanish ''arroyo'' (, "brook"))) or wash is a dry Stream#Other terminology, watercourse that temporarily or seasonally fills and flows after sufficient rain. Flash floods are common in arroyos following thunderstorms. It is akin to the Catalan language, Catalan rambla, which stems from the Arabic ''rámla'', "dry river". Similar landforms are referred to as ''wadi'' (in North Africa and Western Asia), ''chapp'' in the Gobi, ''laagate'' in the Kalahari, ''donga'' in South Africa, ''nullah'' in India, ''fiumare'' in Italy, and ''dry valley'' in England. The desert dry wash biome is restricted to the arroyos of the southwestern United States. Arroyos provide a water source to desert animals. Types and processes Arroyos can be natural fluvial landforms or constructed flood control channels. The term usually applies to a Grade (slope), sloped or mountainous terrain in xeric and desert climates. In addition: in many rural communities arroyos are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sabkha
A sabkha () is a predominately coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of a semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal plains just above normal high-tide level. Within a sabkha, evaporite-saline mineral sediments typically accumulate below the surface of mudflats or sandflats. Evaporite-saline minerals, tidal-flood, and aeolian deposits characterize many sabkhas found along modern coastlines. The accepted type locality for a sabkha is at the southern coast of the Persian Gulf, in the United Arab Emirates.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Tucker, M.E. and Wright, V.P., 2009. ''Carbonate sedimentology.'' John Wiley & Sons. and Warren, J.K., 2006. Evaporites: sediments, resources and hydrocarbons. Springer Science & Business Media ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Braided Stream
A braided river (also called braided channel or braided stream) consists of a network of river channels separated by small, often temporary, islands called '' braid bars'' or, in British English usage, '' aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment loads or coarse grain sizes, and in rivers with steeper slopes than typical rivers with straight or meandering channel patterns. They are also associated with rivers with rapid and frequent variation in the amount of water they carry, i.e., with " flashy" rivers, and with rivers with weak banks. Braided channels are found in a variety of environments all over the world, including gravelly mountain streams, sand bed rivers, on alluvial fans, on river deltas, and across depositional plains. Description A braided river consists of a network of multiple shallow channels that diverge and rejoin around ephemeral ''braid bars''. This gives the river a fancied resemblance to the interwoven strands of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haid Al-Jazil
Haid al-Jazil is one of the villages in Daw'an District in Hadhramaut Governorate, which has a population of 17 according to the 2004 census. The mud-brick buildings of the village are built on a huge boulder overlooking the Wadi Dawan valley. References External linksTowns and villages in the Hadhramaut Governorate Populated places in Hadhramaut Governorate Villages in Yemen {{Hadhramaut-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Hydrology
''Journal of Hydrology'' () is a peer-reviewed academic journal published by Elsevier Elsevier ( ) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell (journal), Cell'', the ScienceDirect collection of electronic journals, ... about hydrological sciences including water based management and related policy issues. External links * Hydrology journals Elsevier academic journals {{Hydrology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eolianite
Eolianite or aeolianite is any rock formed by the lithification of sediment deposited by aeolian processes; that is, the wind. In common use, however, the term refers specifically to the most common form of eolianite: coastal limestone consisting of carbonate sediment of shallow Marine (ocean), marine biogenic origin, formed into coastal dunes by the wind, and subsequently lithified. It is also known as kurkar in the Middle East, miliolite in India and Arabia, and grès dunaire in the eastern Mediterranean. eolianite has a hardness of 4.3 and is very dull. Streak is light brown. Description Sayles coined the term in 1931, when he described the dune-shaped hills of Bermuda, consisting of bioclastic grainstones. Thus, Bermuda is considered the type locality (geology), type locality for carbonate eolianite facies, with clearly defined cross-bedding, foresets, and topsets. Deposition is controlled by glacio-eustatic changes, with eolianites forming during interglaciations. Eolian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity
Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical quantity, quantity, meaning that both magnitude and direction are needed to define it. The Scalar (physics), scalar absolute value (Magnitude (mathematics), magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the International System of Units, SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Definition Average velocity The average velocity of an object over a period of time is its Displacement (geometry), change in position, \Delta s, divided by the duration of the period, \Delt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a single continent, the Americas or America is the 2nd largest continent by area after Asia, and is the 3rd largest continent by population. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with their Lists of islands of the Americas, associated islands, the Americas cover 8% of Earth's total surface area and 28.4% of its land area. The topography is dominated by the American Cordillera, a long chain of mountains that runs the length of the west coast. The flatter eastern side of the Americas is dominated by large river basins, such as the Amazon basin, Amazon, St. Lawrence River–Great Lakes, Mississippi River System, Mississippi, and Río de la Plata Basin, La Plata basins. Since the Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanish Language
Spanish () or Castilian () is a Romance languages, Romance language of the Indo-European languages, Indo-European language family that evolved from the Vulgar Latin spoken on the Iberian Peninsula of Europe. Today, it is a world language, global language with 483 million native speakers, mainly in the Americas and Spain, and about 558 million speakers total, including second-language speakers. Spanish is the official language of List of countries where Spanish is an official language, 20 countries, as well as one of the Official languages of the United Nations, six official languages of the United Nations. Spanish is the world's list of languages by number of native speakers, second-most spoken native language after Mandarin Chinese; the world's list of languages by total number of speakers, fourth-most spoken language overall after English language, English, Mandarin Chinese, and Hindustani language, Hindustani (Hindi-Urdu); and the world's most widely spoken Romance language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canyons
A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering. A canyon may also refer to a rift between two mountain peaks, such as those in ranges including the Rocky Mountains, the Alps, the Himalayas or the Andes. Usually, a river or stream carves out such splits between mountains. Examples of mountain- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
