Since Earth's water cycle is balanced, the average annual precipitation worldwide must equal the quantity of water infiltrated.
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Any change in base level will cause a corresponding readjustment of stream activities.
Building a dam will lower the base level of a stream upstream from the dam.
The base level is the termination of vertical erosion, it is the elevation at which a river enters a large standing body of water, such as a lake or ocean.
The delta is typically built by three kinds of beds, topset beds, forest beds and bottomset bed.