delta

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A deposit of sediment at the mouth of a river or tidal inlet. It is also used for storm washovers of barrier islands and for sediment accumulations at the mouths of submarine canyons. See also Floodplain.

The shape and internal structure of a delta depend on the nature and interaction of two forces: the sediment-carrying stream from a river, tidal inlet, or submarine canyon, and the current and wave action of the water body in which the delta is building. This interaction ranges from complete dominance of the sediment-carrying stream (still-water deltas) to complete dominance of currents and waves, resulting in redistribution of the sediment over a wide area (no deltas). This interaction has a large effect on the shape and structure of the delta body.

Most of the sediment carried into the basin is deposited when the inflowing stream decelerates. If there is little density contrast, this deceleration is sudden and most sediment is deposited near the mouth of the river. If the inflowing water is much lighter than the basin water, for example, fresh water flowing into a colder sea, the outflow spreads at the surface over a large distance away from the outlet. If the inflow is very dense, for instance, cold muddy water in a warm lake, it may form a density flow on or near the bottom, and the principal deposition may occur at great distance from the outlet.

Three principal components make up the bodies of most deltas in varying proportions: topset, foreset, and bottomset beds. As defined for most deltas, the topset beds comprise the sediments formed on the subaerial delta: channel deposits, natural levees, floodplains, marshes, and swamp and bay sediments. The foreset beds are those formed in shallow water, mostly as a broad platform fronting the delta shore, and the bottomset beds are the deep-water deposits beyond the deltaic bulge. In marine deltas the fluviatile influence decreases and the marine influence increases from the topset to the bottomset beds.

In a different way, deltas can be viewed as being composed of three structural elements: (1) a framework of elongate coarse bodies (channels, river-mouth bars, levee deposits), which radiate from the apex to the distributary mouths (sand fingers); (2) a matrix of fine-grained floodplain, marsh, and bay sediments; and (3) a littoral zone, usually of beach and dune sands which result from sorting and longshore transport of river-mouth deposits by waves, currents, tides, and wind. The relative proportions of these components vary widely. The Mississippi delta consists almost entirely of framework and matrix; its rapid seaward growth is the result of deposition of river-mouth bars and extension of levees, and the areas in between are filled later with matrix. This gives the delta its characteristic bird-foot outline. A different makeup is presented by the Rhone delta, where the supply of coarse material at the distributary mouths is slow, and dispersal by wave action and longshore drift fairly efficient, so that nearly all material is evenly redistributed as a series of coastal bars and dunes across a large part of the delta front. This delta advances as a broad lobate front, while the present Mississippi delta grows at several localized and sharply defined points.

Despite difficult engineering problems, many cities, such as Calcutta, Shanghai, Venice, Alexandria (Egypt), and New Orleans, were constructed on deltas. These problems include shifting and extending shipping channels; lack of firm footing for construction except on levees; steady subsidence; poor drainage; and extensive flood danger. Moreover, in certain deltas the tendency of the main flow to shift away to entirely different areas, with resulting disappearance of the main channels for water traffic, is a constant problem that is difficult and costly to counter. See also Estuarine oceanography.

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(Commtalk) D.

• Materials, Formations, and Substances - delta: sediment deposited at river mouth
• Plains and Marshes - delta: nearly flat alluvial plain at mouth of river, usu. triangular

Look up delta in Wiktionary, the free dictionary.

Delta commonly refers to:

• Delta (letter), Δ or δ in the Greek alphabet, also used as a mathematical symbol
• River delta, a landform at the mouth of a river
• Delta Air Lines, a major U.S. airline
  • Delta Connection
  • Delta Express
  • Delta Shuttle

Delta may also refer to:

Contents 1 Places 1.1 Argentina 1.2 Canada 1.3 Egypt 1.4 Nigeria 1.5 People's Republic of China 1.6 United States 2 Culture and society 2.1 Education 2.2 Entertainment and fiction 2.3 Companies 2.4 Organizations 3 Science and technology 3.1 Computer science 3.2 Earth sciences 3.3 Mathematics 3.4 Medicine and biology 3.5 Physics 4 Vehicles 5 Films 6 Other uses 7 People with the name 8 See also

Places

Argentina

• Paraná Delta

Canada

• Delta, British Columbia
  • Delta (provincial electoral district)
  • Delta (electoral district)
• Delta, Ontario, a village within the township of Rideau Lakes, Ontario

Egypt

• Nile Delta

Nigeria

• Delta State
• Niger Delta

People's Republic of China

• Pearl River Delta
• Yangtze River Delta

United States

• Delta, Alabama
• Delta, Colorado
• Delta, Illinois
• Delta, Iowa
• Delta, Louisiana
• Delta, Missouri
• Delta, Ohio
• Delta, Pennsylvania
• Delta, Utah
• Delta, Wisconsin, a town
• Delta (community), Wisconsin, an unincorporated community

Culture and society

Education

• DELTA (ELT), a professional qualification in English language teaching
• Delta, a quadra group used in socionics

Entertainment and fiction

• Delta (album), a 2007 album by Delta Goodrem
• Delta (Visions of Atlantis album), a 2011 album by symphonic metal band Visions of Atlantis
• "Delta", a song by Crosby, Stills & Nash from Daylight Again
• Delta (DVD)
• Delta (TV series), a 1992 TV series starring Delta Burke
• Delta (video game), a 1987 computer game
• Delta FM or Delta Radio, a former UK radio station
• Delta, a codename used by Jason Bourne in The Bourne Identity
• E-103 Delta, a robot character in Sonic the Hedgehog
• Delta Megazord, a zord in Power Rangers in Space
• Deltas, the working class of Aldous Huxley's Brave New World
• Delta AI, a supporting character in Red vs. Blue
• Subject Delta, the protagonist of Bioshock 2
• Delta Squad, the main characters in Gears of War

Companies

Along with the aforementioned Delta Airlines, other companies named Delta include:

• Delta (pen manufacturer), a manufacturer of fine writing instruments
• Delta Cafés, a Portuguese coffee roasting and coffee packaging company
• Delta Electric Company, defunct electrical parts company
• Delta Electricity, an Australian power generation company
• Delta Electronics, a power supplies and brushless fans manufacturer
• Delta Faucet Company, a plumbing fixtures company
• Delta Holding, a Serbian import-export, banking, insurance and retail corporation
• Delta Hotels, a Canadian hotel chain
• Delta Machinery, a stationary power tools and equipment company
• Delta Motor Corporation, a South African car manufacturer owned by General Motors
• Visa Delta or Visa Debit

Organizations

• Delta Dental, an American dental plan system
• Delta Force, a U.S. Army special operations force
• Delta Sigma Theta, an incorporated Howard University public service sorority founded in 1913 by the 22 members of the 1912 Alpha Chapter of the Alpha Kappa Alpha sorority
• Delta Works, a flood-protection works in the Netherlands
• Delta, the call sign for Beredskapstroppen, a Norwegian special police forces team

Science and technology

Computer science

• Delta (computer), a Russian ZX Spectrum clone
• Delta encoding, a technique in computer communications and version-control

Earth sciences

• Delta switching, the process by which some rivers change their course near their deltas
• Tropical Storm Delta (2005), a tropical storm of the 2005 Atlantic hurricane season
• Δ, or epicentral distance

Mathematics

• (ε, δ)-definition of limit
• Delta (finance), a first order derivative of an option pricing formula versus the underlying spot price
• Delta method, a method for approximating the distribution of a function of a random variable
• Δ, or difference operator
• Δ, or modular discriminant
• Δ, or symmetric difference
• Δ, a change of state between two before and after state schemas in the Z notation
• a classification in the arithmetical hierarchy
• a classification in the analytical hierarchy
• a classification in the polynomial hierarchy
• , an inverted delta representing del, a vector differential operator
• Delta connective, a unary connective in t-norm fuzzy logics
• , the Kronecker delta function
• , the Dirac delta function

Medicine and biology

• Delta (genus), Old World genus of potter wasps
• Delta (ligand), an activator of the Notch signaling pathway
• DELTA (taxonomy), a data format used in taxonomy for recording descriptions of living things
• Delta wave, the frequency band of brain activity between 1 and 4 hertz
• Delta wave, on an ECG, the slurred upstroke of the QRS complex which is characteristic of Wolff–Parkinson–White syndrome

Physics

• Delta baryon, a subatomic particle with spin 3/2
• High-leg delta, three phase electrical circuit

Vehicles

• Delta (rocket family), a family of launch vehicles
• Delta class submarine, a Soviet/Russian SSBN submarine series (NATO reporting name)
• Delta Formation, an aircraft formation flying manoeuvre in the shape of a V
• Delta robot, a specialized type of robot
• Delta wing, an aircraft wing planform in the form of a triangle
• Oldsmobile Delta 88, a full-size General Motors car made from 1965 to 1983
• GM Delta platform, a compact car automobile platform from General Motors
• Lancia Delta, an Italian rally car
• Delta, a tricycle layout

Films

• The Delta Force and its sequels

Other uses

• Ilford Delta, a photographic film
• Delta, the refractory section in the roof of an electric arc furnace
• Delta, a font designed by Aldo Novarese

People with the name

• Penelope Delta (1874–1941), Greek author
• Delta Burke (born 1956), American actress
• Delta Goodrem (born 1984), Australian singer
• Delta (wrestler) (born 1985), Mexican professional wrestler

See also

• Delta County (disambiguation)
• Mississippi Delta (disambiguation)
• Arkansas Delta
• All pages with titles containing "Delta"

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Dansk (Danish)
n. - floddelta, delta, fjerde bogstav i det græske alfabet, fjerde stjerne i stjernebillede

idioms:

• delta connection    deltaforbindelse, trekantsforbindelse
• delta rays    deltastråler
• delta wing    deltavinge

Nederlands (Dutch)
(rivier)delta, delta (Griekse letter d)

Français (French)
n. - delta

idioms:

• delta connection    (Élec) montage en triangle
• delta rays    (Phys Nucl) rayons delta
• delta wing    (Sport) aile delta

Deutsch (German)
n. - Delta, Deltamündung

idioms:

• delta connection    (electr.) Dreieckschaltung
• delta rays    Deltastrahlen
• delta wing    Deltaflügel

Ελληνική (Greek)
n. - (γεωγρ.) δέλτα (ποταμού), (φυσ.) (για ηλεκτρικές συνδέσεις κ.λπ.) δέλτα

idioms:

• delta connection    σύνδεση δέλτα
• delta rays    (φυσ.) ακτίνες δέλτα
• delta wing    (τεχνολ.) τριγωνική πτέρυγα

Italiano (Italian)
delta

idioms:

• delta connection    triangolo
• delta rays    raggi delta
• delta wing    ala a delta

Português (Portuguese)
n. - delta (f)

idioms:

• delta connection    ligação (f) em triângulo (Eletr.)
• delta rays    raios (m pl) delta
• delta wing    asa (f) delta

Русский (Russian)
дельта

idioms:

• delta connection    соединение треугольником
• delta rays    дельта-излучение
• delta wing    треугольное крыло

Español (Spanish)
n. - delta, algo triangular, cuarto, incremento, cuarta estrella más brillante en una constelación

idioms:

• delta connection    conexión en delta
• delta rays    rayos delta
• delta wing    ala delta

Svenska (Swedish)
n. - delta

中文（简体）(Chinese (Simplified))
三角洲, 希腊字母第四个

idioms:

• delta connection    三角连接
• delta rays    delta射线
• delta wing    翼呈三角形的, 三角翼的

中文（繁體）(Chinese (Traditional))
n. - 三角洲, 希臘字母第四個

idioms:

• delta connection    三角連接
• delta rays    delta射線
• delta wing    翼呈三角形的, 三角翼的

한국어 (Korean)
n. - 델타(그리스어의 알파벳의 넷째자), 삼각주

日本語 (Japanese)
n. - 三角州, デルタ, 三角形のもの

idioms:

• delta connection    デルタ結線
• delta rays    デルタ線, デルタ線の飛跡
• delta wing    デルタ翼, 三角翼, デルタ翼機

العربيه (Arabic)
‏(الاسم) الحرف الرابع من الأبجديه اليونانيه, أرض مثلثه الشكل تقع على مصب النهر ومتقاطعه مع أفرع النهر المنصبه في البحر‏

עברית (Hebrew)
n. - ‮דלתא, דלתה‬

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