1. Relating to or consisting of any material that has been carried or deposited by running water: The result of the soil being washed away by water may result in an alluvial valley or an alluvial deposit, all of which consist of earth and sand that has been left by rivers, floods, etc.

The most alluvial deposits that have ever been recorded in Fred's community took place recently during the severe flooding.

2. Etymology: borrowed from Medieval Latin alluvium, alluvius, "washed against", from Latin alluere, "to wash against"; from al-, a form of ad- before l, "to, against", + -luere, a combining form of lavere, "to wash".

An underground water supply which comes from porous rock, sand, gravel, etc.: The alluvial aquifer provided the community with ground water that made it possible for their wells and springs to continue functioning.

A sedimentary deposit (fragments of material) built up by an overloaded stream that is obstructing the stream channel: The alluvial dam of soil composed of sand, silt, and clay were blocking the flow of water.

The accumulation of sediment (mud, sand, etc.) deposited by fresh running water into a channel: The alluvial deposits are controlled by channels, vegetation covers, channel densities, sources of geology, climates, and dirt surface deformations.

A gently sloping wedge-shaped mass of sediment deposited by a stream where it comes from a narrow canyon onto a plain or valley floor: Alluvial fans accumulate at and spread from the base of dry mountain ranges where a mountain stream, no longer confined to its narrow channel, deposits its coarse sediment into a large sloping apron-like structure at the point where it comes out onto the plain.

When a stream divides into branching and intertwining lower channels that are separated by islands or sandbars, they twist their way through the fan format and carry sediment from the fan's apex to its fringes and so become alluvial fans.

Alluvial fans also develop in front of melting glaciers, when the water flows out from the ice and spreads out a large amount of coarse debris with it.

Large alluvial fans have deposits that exist in different sizes within the fan, with the bigger pieces of sediment dropping closest to the mountains and the finer materials deposited farther away as the water moves along.

A small plain where gravel, sand, and mud are deposited on the sides of rivers during floods: Alluvial flats usually form where streams leave earth materials in river valleys or deltas.

Gold that can be found in soil and water sediment deposits.

These deposits are usually found around rivers, streams, or any other sort of running water.

The process of dredging (scooping out of the mud) or following horizontal tunnels to exploit materials that have been carried, washed, or left behind by running water: Alluvial mining involves the processing of deposits that are carried by rushing streams and located where the water slows down to remove certain elements from a riverbed, channel, etc.

Various kinds of valuable mineral particles that have been transported and deposited by a river or a stream: Don, the old prospector, mined the alluvial ore along the river, hoping to find gold.

A tract of gently sloping land by a river that periodically overflows depositing clay, silt, or gravel which has been brought downstream where the water slows down: Mike and his family decided to pitch their tents on the alluvial plain near the river because it was flat and sandy.

The waste plains look desolate and barren, however they may be rich in minerals that have been washed down by the river creating an alluvial plain.

 

The soil, clay, silt, or gravel that is left by a flowing water surface which goes down and away from a mountainside and merges with a plain or wide valley floor: Alluvial slopes are made up of the surface soil from hills or mountains that have been "washed" by rain during which time the slanting hills deposit bushes and other vegetable matter, plus sand, dirt, and mud slides, all of which are carried down and left in areas of flat land, such as valleys.

The earth developed on flood plains and deltas, having only the characteristics of the clay, silt or gravel carried by rushing streams and deposited where the streams slow down: The alluvial soils leave a fine-grained earth material consisting of very tiny particles of sand and clay, all of which are deposited by water flowing over flood plains or into river beds.

Keith and the other farmers near the mouth of the river found that the alluvial soils were much more fertile than the land farther away from the river.

Fine-grained fertile earth deposited by water flowing over flood plains or in river beds: Keith and the other farmers near the mouth of the river found that the alluvial soils were much more fertile than the land farther away from the river.

Alluvial soil is rich and fertile earth and can be found in aquatic communities (living in or on water for all or a substantial part of the life span and is generally restricted to fresh water or inland waters).

A raised embankment or a gently sloping geomorphic surface of loose, unconsolidated earth material that has built up next to the sides of a river valley: The geology teacher, Mr. Lange, told his students that an alluvial terrace was a land area that came from a previously formed floodplain that was formed by a stream or river.

The alluvial terrace is also know as a built terrace, a drift terrace, a fill terrace, a stream-built terrace, a wave-built platform, and a wave-built terrace.