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An alluvial plain is a largely flat
landform A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, ...
created by the deposition of
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...
over a long period of time by one or more
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
s coming from highland regions, from which
alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...
soil forms. A
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
is part of the process, being the smaller area over which the rivers flood at a particular period of time, whereas the alluvial plain is the larger area representing the region over which the floodplains have shifted over geological time. As the highlands erode due to
weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs '' in situ'' (on site, with little or no movement ...
and water flow, the
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...
from the hills is transported to the lower
plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...
. Various creeks will carry the water further to a river,
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
,
bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a na ...
, or
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
. As the sediments are deposited during flood conditions in the
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
of a creek, the elevation of the floodplain will be raised. As this reduces the channel floodwater capacity, the creek will, over time, seek new, lower paths, forming a
meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ban ...
(a curving sinuous path). The leftover higher locations, typically natural
levee A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastli ...
s at the margins of the flood channel, will themselves be eroded by lateral stream erosion and from local rainfall and possibly wind transport if the climate is arid and does not support soil-holding grasses. These processes, over geologic time, will form the plain, a region with little
relief Relief is a sculptural method in which the sculpted pieces are bonded to a solid background of the same material. The term '' relief'' is from the Latin verb ''relevo'', to raise. To create a sculpture in relief is to give the impression that th ...
(local changes in elevation), yet with a constant but small slope. The ''Glossary of Landform and Geologic Terms'', maintained by the United States' National Cooperative Soil Survey, defines an "alluvial plain" as "a large assemblage of fluvial landforms (braided streams, terraces, etc.,) that form low gradient, regional ramps along the flanks of mountains and extend great distances from their sources (e.g., High Plains of North America)" Use of "alluvial plain" as a general, informal term for a broad flood plain or a low-gradient delta is explicitly discouraged. The NCSS glossary instead suggests "flood plain".


Examples

* Canterbury Plains, Southland Plains, and Waikato Plains in
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
*
Chianan Plain Chianan or Jianan may refer to: Taiwan * Chianan Plain, largest plain in Taiwan * Chianan Irrigation, canals of Chianan Plain of Taiwan Han Dynasty *Jian'an, name for the period of rule (196—220) of the Emperor Xian of Han *Seven Scholars of J ...
in
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...
* Lower Danubian Plain,
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
and
Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
*
Indo-Gangetic Plain The Indo-Gangetic Plain, also known as the North Indian River Plain, is a fertile plain encompassing northern regions of the Indian subcontinent, including most of northern and eastern India, around half of Pakistan, virtually all of Bangla ...
and
Punjab Punjab (; Punjabi Language, Punjabi: پنجاب ; ਪੰਜਾਬ ; ; also Romanization, romanised as ''Panjāb'' or ''Panj-Āb'') is a geopolitical, cultural, and historical region in South Asia, specifically in the northern part of the I ...
in
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
,
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
, and
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...
* Iskar (river) valleys in Bulgaria * Mekong Delta in
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making ...
* Mesaoria in
Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ...
*
Mesopotamia Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
in
Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
* Mississippi Alluvial Plain,
Oxnard Plain The Oxnard Plain is a large coastal plain in southwest Ventura County, California, United States surrounded by the mountains of the Transverse ranges. The cities of Oxnard, Camarillo, Port Hueneme and much of Ventura as well as the unincorpo ...
, and
Laguna de Santa Rosa The Laguna de Santa Rosa is a wetland complex that drains a watershed encompassing most of the Santa Rosa Plain in Sonoma County, California, United States. The California Office of Environmental Health Hazard Assessment has issued a safe eati ...
in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
* North China Plain in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
*
Palakaria The Palakaria ( bg, Палакария) is a river in south-western Bulgaria, a left tributary of the Iskar. The river is 39 km long and takes its source from the southern slopes of the summit of Kupena in Vitosha mountain range at an altit ...
Valley in
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
*
Po Valley The Po Valley, Po Plain, Plain of the Po, or Padan Plain ( it, Pianura Padana , or ''Val Padana'') is a major geographical feature of Northern Italy. It extends approximately in an east-west direction, with an area of including its Venetic ex ...
in
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
* Rhine–Meuse–Scheldt in the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
* Struma Valley in Bulgaria * Tundzha valleys in Bulgaria * Multiple sites in
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
* Upper Thracian Plain in Bulgaria *
Baetic Depression The Baetic Depression ( es, Depresión Bética or ''Depresión del Guadalquivir'') is an alluvial plain in the lower valley of the Guadalquivir in Andalusia, Spain. It is a large triangular-shaped area in the Guadalquivir basin oriented roughly ...
in
Andalusia Andalusia (, ; es, Andalucía ) is the southernmost autonomous community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a "historical nationality". The ...
,
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
* Santa Clara Valley in
San Jose, California San Jose, officially San José (; ; ), is a major city in the U.S. state of California that is the cultural, financial, and political center of Silicon Valley and largest city in Northern California by both population and area. With a 2020 popu ...
Santa Clara Valley Groundwater Basin, East Bay Plain Subbasin


See also

* Alluvial fan *
Alluvium Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...
* Coastal plain * Desert pavement *
River delta A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rare ...


References

{{Authority control Fluvial landforms + Geography terminology