watercourse
Natural flow of water that varies in size, depending on the ground slope and the number of tributaries.
spring
Point where underground water rises to the surface; it may be the source of a watercourse.
waterfall
Almost vertical flow of a watercourse, caused by a sudden change in the level of its bed.
lake
Body of water completely surrounded by land; it varies in size and depth.
delta
Section of the coastline where sediment builds up at the mouth of a river, divided into several arms.
sea
Vast body of saltwater at some distance inland; it is not as deep as an ocean.
floodplain
Level surface bordering a watercourse; it is subject to periodic flooding.
delta distributary
Channel that a river or stream follows near its mouth; several arms, separated by alluvial deposits, form a delta.
alluvial deposits
Sediment (mud, sand, gravel, pebbles) transported and then deposited by a watercourse.
oxbow
Meander in which only a narrow neck of land remains between the two parts of the watercourse.
river
Natural watercourse fed by numerous smaller streams; it empties into a larger river or the sea.
plain
Vast, relatively flat expanse of land, lower than the surrounding landscape; its valleys are wide and shallow.
valley
Elongated depression shaped by a watercourse or glacier and bounded by the slopes of the surrounding land.
gorge
Deep narrow valley bounded by steep or very sheer slopes, carved out by a watercourse.
river
Natural watercourse fed by numerous smaller streams; it empties into a larger river or the sea.
glacier
Mass of ice resulting from the accumulation and compression of snow; it moves under its own weight.
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