Alluvial plain facts for kids

This picture shows a floodplain (in the middle) inside the bigger alluvial plain of the Waimakariri River in New Zealand.

A small alluvial plain that has been cut into by a river in Red Rock Canyon State Park (California).

An alluvial plain is a mostly flat area of land. It's made over a very long time by rivers that drop off dirt, sand, and rocks (called sediment) as they flow from mountains or hills. This sediment builds up, forming a special kind of soil called alluvial soil.

You might have heard of a floodplain. A floodplain is a smaller area where a river floods at a certain time. An alluvial plain is much bigger. It's the whole area where floodplains have moved and changed over thousands or millions of years.

As mountains and hills slowly wear away from weather and water, the dirt and rocks are carried down to the flatter land below. Small streams carry this water and sediment to bigger rivers, lakes, bays, or even the ocean. When rivers flood, they leave behind sediment on the floodplain, which makes the land get higher.

Over time, if the river channel gets too full of sediment, the river will find new, lower paths. This often creates curvy paths called meanders. The higher parts of the land, like natural banks along the river, can be worn away by the river moving sideways, by rain, or even by wind if the area is very dry. All these processes, happening over a very, very long time, create the alluvial plain. It's a flat area that slopes gently downwards.

Alluvial plains are a bit like river deltas. However, deltas always flow into a big body of water like an ocean or a large lake. Alluvial plains usually don't end in a large body of water in the same way.

Where Can You Find Alluvial Plains?

Alluvial plains are found all over the world. Here are some famous examples:

Alluvial Plains in the Americas

• The Mississippi Alluvial Plain, Oxnard Plain, and Laguna de Santa Rosa in the United States.
• The Santa Clara Valley in San Jose, California.
• The Tempisque River plain in Costa Rica.
• The Middle Amazon region in Brazil.

Alluvial Plains in Asia & Oceania

• The Canterbury Plains, Southland Plains, and Waikato Plains in New Zealand.
• The Chianan Plain in Taiwan.
• The Indo-Gangetic Plain and Punjab in India, Pakistan, and Bangladesh.
• The Mekong Delta in Vietnam.
• Mesopotamia in Iraq, known as the "Cradle of Civilization."
• The North China Plain in China.

Alluvial Plains in Europe

• The Baetic Depression in Andalusia, Spain.
• The Lower Danubian Plain in Bulgaria and Romania.
• The Iskar (river) valleys in Bulgaria.
• Mesaoria in Cyprus.
• Many places in Switzerland (see list of alluvial sites).
• The Palakaria Valley in Bulgaria.
• The Po Valley in Italy.
• The Rhine–Meuse–Scheldt area in the Netherlands.
• The Haute vallée de la Sarthe in France.
• The Struma Valley in Bulgaria.
• The Tundzha valleys in Bulgaria.
• The Upper Thracian Plain in Bulgaria.

See also

• Alluvial fan
• Alluvium
• Coastal plain
• Desert pavement
• Floodplain
• River delta