An alluvial plain is a largely flat landform 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, sa ...

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 w ...

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. All ...

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 Erode () is a city in the Indian state of Tamil Nadu. Erode is the seventh largest urban agglomeration in the state, after Chennai, Coimbatore, Madurai, Tiruchirapalli, Tiruppur and Salem. It is also the administrative headquarters of the ...

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

from the hills is

transported ''Transported'' is an Australian convict melodrama film directed by W. J. Lincoln. It is considered a lost film. Plot In England, Jessie Grey is about to marry Leonard Lincoln but the evil Harold Hawk tries to force her to marry him and she w ...

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, 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 wo ...

. As the sediments are deposited during flood conditions in the

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 ba ...

(a curving sinuous path). The leftover higher locations, typically natural levees 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 The National Cooperative Soil Survey Program (NCSS) in the United States is a nationwide partnership of federal, regional, state, and local agencies and institutions. This partnership works together to cooperatively investigate, inventory, docume ...

, 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 The Canterbury Plains () are an area in New Zealand centred in the Mid Canterbury, to the south of the city of Christchurch in the Canterbury region. Their northern extremes are at the foot of the Hundalee Hills in the Hurunui District, and in t ...

Southland Plains The Southland Plains is a general name given to several areas of low-lying land in the South Island of New Zealand, separated by the rise of the Hokonui Hills in the north. It forms a sizeable area of Southland region and encompasses its two pr ...

, and

Waikato Plains The Waikato Plains form a large area of low-lying land in the northwest of the North Island of New Zealand. They are the alluvial plains of the ancient Waikato River, the country's longest river that over the last 1800 years has changed course man ...

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 count ...

* Chianan Plain 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 nort ...

* 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, Eastern, and Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, Moldova to the east, and ...

* Indo-Gangetic Plain and

Punjab Punjab (; Punjabi: پنجاب ; ਪੰਜਾਬ ; ; also romanised as ''Panjāb'' or ''Panj-Āb'') is a geopolitical, cultural, and historical region in South Asia, specifically in the northern part of the Indian subcontinent, comprising a ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...

, 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 mos ...

Iskar (river) The Iskar ( bg, Искър, ; la, Oescus) is a right tributary of the Danube. With a length of 368 km it is the longest river that runs entirely within 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 i ...

Mesaoria The Mesaoria ( el, Μεσαορία, tr, Mesarya) is a broad, sweeping plain which makes up the north centre of the island of Cyprus. Geography The Mesaoria is the name given to the broad tract of plain which extends across the island from the ...

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 ge ...

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 ...

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 the north, Iran to the east, the Persian Gulf and K ...

Mississippi Alluvial Plain The Mississippi River Alluvial Plain is an alluvial plain created by the Mississippi River on which lie parts of seven U.S. states, from southern Louisiana to southern Illinois (Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, Lo ...

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 unincorpora ...

, 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 e ...

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 primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

* North China Plain in China * Palakaria Valley in

* Po Valley 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 The Tundzha ( bg, Тунджа , tr, Tunca , el, Τόνζος ) is a river in Bulgaria and Turkey (known in antiquity as the Tonsus) and the most significant tributary of the Maritsa, emptying into it on Turkish territory near Edirne. The rive ...

valleys in Bulgaria * Multiple sites in Switzerland *

Upper Thracian Plain The Upper Thracian Plain ( bg, Горнотракийска низина, ''Gornotrakiyska nizina'') constitutes the northern part of the historical region of Thrace. It is located in southern Bulgaria, between Sredna Gora mountains to the north ...

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 ...

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 t ...

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") , i ...

Santa Clara Valley The Santa Clara Valley is a geologic trough in Northern California that extends 90 miles (145 km) south–southeast from San Francisco to Hollister. The longitudinal valley is bordered on the west by the Santa Cruz Mountains and on the east ...

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

References

{{Authority control Fluvial landforms + Geography terminology

Examples

See also

References