delta

The delta (the original character to hide for, delta) has shape that it is near in a triangle surrounded in two of them river (an arm of a river) and the sea more than it which branched off by the topography seen in the vicinity of the river mouth. Because I resemble the delta (Δ) of Greek characters, I am called delta, the delta zone.

It is formed by the sand which flowed from the upper reaches of the river accumulating. Plural deltas can be formed in the river mouth in the case of the big river, and there can be the thing that delta calls them a delta again generally.

A condition of the formation is that earth and sand supply of enough quantity from the river, form which seafloor topography of the neighborhood of river mouth can accumulate with the earth and sand, a tide of the river mouth neighborhood do not erode too much with the earth and sand.

By the combination of the condition mentioned above, as for the form of the delta, it is it with arc-shaped delta and cusp-shaped [form of apex] delta, not form of simple delta.

Generally because a slope is steep in the river of monsoon Asia, and the flow quantity is big, the transportation action of the river is big, and there are many cases forming a delta in the river mouth. The delta is used mainly in monsoon Asia by a rice field.