A delta is a landform where the mouth of a river flows into an ocean, sea, estuary, lake or another river. "Riverine" redirects here For the use of that term in Maritime geography, see there An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. This article is about the body of water For other uses see SEA and Seas. An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the A delta is formed only when a channel deposits sediment into another body of water. It builds up sediment outwards into the flat area which the river's flow encounters (as a deltaic deposit) transported by the water and set down as the currents slow. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of Deltaic deposits of larger, heavily-laden rivers are characterized by the main channel dividing amongst often substantial land masses into multiple streams known as distributaries. Physical geography, a channel is the physical confine of a River, slough or ocean Strait consisting of a bed and banks A distributary, or a distributary channel, is a Stream that branches off and flows away from a main stream channel These divide and come together again to form a maze of active and inactive channels. This hydrogeologic formation is known as a delta. A delta can sometimes be misinterpreted as an alluvial fan. An alluvial fan is a fan -shaped deposit formed where a fast flowing Stream flattens slows and spreads typically at the exit of a Canyon onto The two terms, however, are not interchangeable. A delta is formed in water and an alluvial fan occurs on land.
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Delta formation
The deposit at the mouth of a river is usually roughly triangular in shape. The triangular shape and the increased width at the base are due to blocking of the river mouth, with resulting continual formation of distributaries at angles to the original course. A distributary, or a distributary channel, is a Stream that branches off and flows away from a main stream channel These distributaries start out flowing fairly fast, but slow as more sediment is deposited and ultimately, the water flows elsewhere. Change in the depositional process is directly related to a river or streams competency (the size of particles it can transport) and its capacity ( the amount of material it can move). This change in flow affects the particle size in the suspended and bed loads, the size of the particles decrease as the flow slows and the larger particles are deposited. Suspended Load hweuwqrfor the fine particles that are light enough to be carried in a Stream without touching the Stream bed. The term Bed load describes particles in a flowing fluid (usually a river that are transported along the bed This deposition goes on continually in a cyclic fashion, creating alternating sediment beds of coarse and fine grain deposits. In Geology a bed is the smallest division of a Geologic formation or stratigraphic rock series marked by well-defined divisional planes (bedding planes As a channel deposits sediment in one location, it becomes more difficult for the channel to reach the body of water. As this occurs, the channel will change course to go by the way of steepest gradient. This happens continuously as the channel moves back and forth from the mouth of the river. As sediment is laid down in this fashion, the predictable fan-shape of the delta is formed. Herodotus the great historian used this term for the Nile river delta because the sediment deposit at its mouth had the shape of upper-case Greek letter Delta: Δ. Herodotus of Halicarnassus ( Greek: Hēródotos Halikarnāsseús) was a Greek Historian who lived in the 5th century BC ( 484 BC&ndash The Nile Delta ( Arabic: دلتا النيل) is the delta formed in Northern Egypt ( Lower Egypt) where the Nile River spreads Capital letters or majuscules pronunciation /məˈdʒʌskyuls ˈmædʒəˌskyuls/ in the Roman alphabet A, B, C, D, The Greek alphabet (Ελληνικό αλφάβητο is a set of twenty-four letters that has been used to write the Greek language since the late 9th or early Delta (uppercase Δ, lowercase δ; Δέλτα Thelta is the fourth letter of the Greek alphabet.
Where delta formation is river-dominated and less subject to tidal or wave action, more deposition occurs and a delta may take on a multi-lobed shape which resembles a bird's foot. Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood Ocean surface waves are Surface waves that occur on the Free surface of the Ocean. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. An example of a river dominated delta is the Mississippi River delta. Another type of delta is a wave dominated delta. Deposition is still occurring on this landform, however, waves erode the outer edge of the structure, giving it an even more identifiable delta shape. An example of this is the Nile River delta. The formation of a delta consists of three main forms: the topset, foreset/frontset, and bottomset. The bottomset beds are created from the suspended sediment that settles out of the water as the river flows into the body of water and loses energy. The suspended load is carried out the furthest into the body of water than all other types of sediment creating a turbidite. These beds are laid down in horizontal layers and consist of smaller grains. The foreset beds in turn build over the bottomset beds as the main delta form advances. The foreset beds consist of the bed load that the river is moving along which consists of larger sediments that roll along the main channel. When it reaches the edge of the form, the bed load rolls over the edge, and builds up in steeply angled layers over the top of the bottomset beds. The angle of the outermost edge of the delta is created by the sediments angle of repose. As the forsets build outward (which make up the majority of the delta) they pile up and miniature landslides occur. This slope is created in this fashion as the bedload continues to be deposited and the delta moves outward. In cross section, one would see the foresets lying in angled, parallel bands, showing each stage of the creation of the delta. The topset beds in turn overlay the foresets, and are horizontal layers of smaller sediment size that form as the main channel of the river shifts elsewhere and the larger particles of the bed load no longer are deposited. As the channels move across the top of the delta, the suspended load settles out in horizontal beds over the top. The most famous delta is that of the Nile River, and it is this delta from which the term is derived, because the Nile delta has a very characteristic triangular shape, like the (upper-case) Greek letter delta (Δ). The Nile (النيل, Ancient Egyptian iteru or Ḥ'pī, Coptic piaro or phiaro) is a major north-flowing River A triangle is one of the basic Shapes of Geometry: a Polygon with three corners or vertices and three sides or edges which are Line The Greek alphabet (Ελληνικό αλφάβητο is a set of twenty-four letters that has been used to write the Greek language since the late 9th or early Delta (uppercase Δ, lowercase δ; Δέλτα Thelta is the fourth letter of the Greek alphabet. Ganges/Brahmaputra combination (this delta spans most of Bangladesh and West Bengal) is the world's largest delta, and empties into the Bay of Bengal. The Ganges (ˈgænʤiːz also Ganga, Devanāgarī: hi गंगा in most Indian languages) is the major river in the Indian subcontinent The Brahmaputra, also called Tsangpo-Brahmaputra is a Trans-boundary river and one of the major Rivers of Asia. ( Bengali: বাংলাদেশ inc-Latn Bangladesh) officially West Bengal ( Bengali: পশ্চিমবঙ্গ Poshchim Bônggo poʃtʃim bɔŋgo is a state in eastern India. Other rivers with notable deltas include the Sacramento-San Joaquin, the Mississippi, the Rhine, the Rhône, the Danube, the Ebro, the Volga, the Lena, the Tigris-Euphrates, the Indus, the Krishna-Godavari, the Truckee, the Carson River, the Kaveri, the Ayeyarwady, and the Mekong. The Sacramento River is the longest River entirely within the U The San Joaquin River ( 330 miles (530 km long is the second-longest River in California, United States. The Mississippi River is the second longest River in the United States, with a length of from its source in Lake Itasca in Minnesota to The Rhine (Rhein Rijn Rhin Reno Rain Rhenus is one of the longest and most important Rivers in Europe at 1320 kilometres (820 mi with an average discharge The Rhone, or the Rhône is one of the major Rivers of Europe, running through Switzerland and France. The Danube Delta ( Romanian: Delta Dunării; Ukrainian: Дельта Дунаю Del'ta Dunaju) is the second largest delta The Ebro ( Ebre) is Spain 's most voluminous river Its source is in Fontibre ( Cantabria) The Tigris-Euphrates river system is part of the Tigris-Euphrates alluvial salt marsh Ecoregion of the Middle East, and is characterized by two large The Indus River { Sanskrit: सिन्धु Sindhu; Urdu: urd {{Nastaliq سندھ}} Sindh; Sindhi: snd This article is about an Indian river For other meanings of this river names see Krishna (disambiguation and Krishnaveni. This article is about the river Godavari in India. For other uses see Godavari (disambiguation The Godavari ( Marathi language:गोदावरी The Kaveri River ( Kannada: ಕಾವೇರಿ ನದಿ Tamil: காவிரி ஆறு also spelled Cauvery in English The Ayeyarwady River or Irrawaddy River ( is a River that flows from north to south of Burma (Myanmar The Mekong is one of the world’s major Rivers It is the 11th-longest river in the world and 7th longest in Asia
A Gilbert delta is a specific type of delta that only occurs in fresh water and with coarse sediments. For example, a mountain river depositing sediment into a freshwater lake would form this kind of delta. Other rivers, particularly those located on coasts with significant tidal range, do not form a delta but enter into the sea in the form of an estuary. The tidal range is the vertical difference between the highest High tide and the lowest Low tide. An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open Notable examples include the Saint Lawrence River and the Tagus estuary. Saint Lawrence River (in French: fleuve Saint-Laurent; Kahnawáˀkye in Tuscarora, Kaniatarowanenneh meaning big waterway The Tagus ( Latin Tagus, Spanish Tajo, Portuguese Tejo, pron.
In rare cases the river delta is located inside a large valley and is called an inverted river delta. An inverted river delta is special category of River delta in which the narrow end of the delta emerges on the seafront and the wide end is located further inland so that with Sometimes a river will divide into multiple branches in an inland area, only to rejoin and continue to the sea; such an area is known as an inland delta, and often occur on former lake beds. The Niger Inland Delta is the most notable example. The Niger Inland Delta, also known as the Macina or Inner Niger Delta, is a large area of Lakes and Floodplains in Mali. The Amazon has also an inland delta before the island of Marajo. The Amazon River (Rio Amazonas Río Amazonas of South America is the largest river in the world by volume with a total river flow greater than the next top ten largest rivers Marajó is an Island located at the mouth of the Amazon River in Brazil.
List of deltas
- Camargue (Rhône River Delta)
- Colorado River Delta
- Danube Delta
- Eberswalde (crater) Mars (ancient delta)
- Ebro River
- Fraser River Delta
- Ganges-Brahmaputra Delta
- Indus River Delta
- Chao Phraya River Delta
- Lena Delta
- Mackenzie River Delta
- Mekong Delta
- Mississippi River Delta
- Niger Inland Delta (inland delta)
- Niger River Delta (Oil Rivers)
- Nile Delta
- Ogowe Delta
- Okavango Delta (inland delta)
- Orinoco Delta
- Paraná Delta
- Parnaíba Delta
- Peace-Athabasca Delta (inland)
- Pearl River Delta
- Po Delta
- Rio Grande Valley
- Rhine-Meuse-Scheldt Delta
- Sacramento-San Joaquin River Delta (inverted delta)
- Volga Delta
- Yangtze River Delta
- Yukon Delta
- Tanjore Delta, Kaveri river
See also
External links
- Louisiana State University Geology - World Deltas
The Camargue ( Occitan: Camarga in classical norm or Camargo in Mistralian norm is located south of Arles, France, between the The Rhone, or the Rhône is one of the major Rivers of Europe, running through Switzerland and France. The Colorado River Delta is the region of land where the Colorado River historically flowed into the Gulf of California, (the Sea of Cortez) The Danube Delta ( Romanian: Delta Dunării; Ukrainian: Дельта Дунаю Del'ta Dunaju) is the second largest delta Eberswalde crater, formerly known as Holden NE crater, is a partially buried Impact crater in Margaritifer Terra, Mars. The Ebro ( Ebre) is Spain 's most voluminous river Its source is in Fontibre ( Cantabria) For other uses of this name see Fraser River (disambiguation. The Ganges Delta (also Sunderban Delta or the Bengal Delta) is a River delta in the South Asia region of Bengal, consisting of Bangladesh The Indus River Delta forms where the Indus River flows into the Arabian Sea in Pakistan. The Chao Phraya (แม่น้ำเจ้าพระยา is a major River in Thailand, with its low alluvial river plain marking the mainland of the country Lena Delta Wildlife Reserve is a Zapovednik (“scientific Nature reserve ” located in the delta of the Lena River in The Mackenzie River (Fleuve Mackenzie originates in Great Slave Lake, in the Northwest Territories, and flows north into the Arctic Ocean. The Mekong Delta (đồng bằng sông Cửu Long “Nine Dragon river delta” is the region in southwestern Vietnam where the Mekong River approaches and empties The Mississippi River Delta is the modern area of land (the River delta) built up by Alluvium deposited by the Mississippi River as it slows The Niger Inland Delta, also known as the Macina or Inner Niger Delta, is a large area of Lakes and Floodplains in Mali. The Niger Delta, the delta of the Niger River in Nigeria, is a densely populated region sometimes called the Oil Rivers because it was once a The Nile Delta ( Arabic: دلتا النيل) is the delta formed in Northern Egypt ( Lower Egypt) where the Nile River spreads The Ogooué (or Ogowe) some 1200km long is the principal River of Gabon in west central Africa. The Okavango Delta (or Okavango Swamp) in Botswana, is the world's largest inland delta. The Orinoco Delta, also known as the Deltaic System ( Sistema Deltaico) is a vast River delta of the Orinoco River, located in eastern Venezuela The Paraná Delta is the delta of the Paraná River in Argentina. The Peace-Athabasca Delta is a large freshwater inland delta in northeastern Alberta located where the Peace and Athabasca Rivers join the The Pearl River Delta Region (PRD ( in southern China occupies the low-lying areas alongside the Pearl River Estuary The Rio Grande Valley is an area located in the southernmost tip of Texas. The Rhine (Rhein Rijn Rhin Reno Rain Rhenus is one of the longest and most important Rivers in Europe at 1320 kilometres (820 mi with an average discharge The Meuse (in Dutch and in German: "Maas" in Latin: "Mosa" in Celtic:"Mus" (the rootword presumingly The Scheldt (Dutch Schelde, French Escaut, Latin Scaldis) is a 350 km[http //www The Sacramento-San Joaquin River Delta is an expansive inland River delta and Estuary in northern California in the United States. The Volga Delta is the largest inland River delta in Europe, and occurs where Europe's largest river system the Volga River, drains into the Caspian The Yangtze River Delta or Yangtze Delta, also called Chang Jiang Delta, or the Golden Triangle of the Yangtze ( Hanyu Pinyin:) generally The Yukon-Kuskokwim Delta is one of the biggest River deltas in the world roughly the size of Oregon. Delta switching, also known as avulsion, is the process by which some rivers - such as the Mississippi River - change their course near their deltas An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open Mega delta is a generic term given to the very large Asian River deltas viz An alluvial fan is a fan -shaped deposit formed where a fast flowing Stream flattens slows and spreads typically at the exit of a Canyon onto The formation of a River basin at the mouth of the River is usually characterised by the shape of a delta, the triangular Greek letter.
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