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Submitted By:
Sanjeet Singh
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Formation of river
Three stages of river
Young stage
Middle stage
Old stageThis lovely mountain meadow shows a
stream flowing in a very gently sloping
bed
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The place where a river begins iscalled its source. Rivers begin
high in
the mountains, where melting snow
gathers in small streams. The waterwinds its ways through alpine
meadowsand begins its downward journey.
This picture shows a young riverflowing in its stony bed. You
can
see why people call this "white
water". The water twists this way
and that around the rocks.
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There are three types of river:-
oMiddle stage
oOld Stage
oYoung Stage
Young Stage Of River
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The young river flows swiftly, with many rapidsand waterfalls.
It erodes its bed and cuts anarrow, V-shaped valley with steep
sides.
Notice the very steep sides of this valley andthe powerful
waterfall. As the river flows, it is joined by other steams,
its tributaries. The river has a greater flow ofwater now, and
the river's bed is not so steep.The tributaries are also eroding
the sides ofthe valley. The valleys become wider, and thewalls of
the valleys slope more gradually
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The valley floor becomes almost flat, and the watercan spread
out when the snows melt. In the
mountains the streams form meadows where
aspens and willows begin to grow. Further downthe river's course
the valley becomes a flood plain.
When there is a lot of water catastrophic flooding
can destroy human communities
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In the last part of a river's journey, it flows
through a gently sloping flood plain. Because
the plain is nearly level, the river can wander
across it in a winding, snaking pattern. These
loops and turns are called meanders. A
meandering river flowing through a floodplain
is called a mature river.
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A mature river carries a heavy load of
sediment. When the flow of water slows, the
sediment settles to the bottom. Sand bars
begin to appear.
This picture shows the beginning of a meander
pattern that this river formed when the green
terraces in the picture were the floor of the
floodplain. It has started cutting a V shaped
valley again
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The final stage in the life of a river is itsjoining with the
sea. By now the river istraveling smoothly and carrying a lot
of
sand and clay. Merging with the sea slowsthe water flow even
more, and thesediment drops out. This often leads to
the formation of a delta, a broad,triangular river mouth with
many sandbars and water channels.
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The delta becomes an estuary, an area withsheltered waters and a
constant stream ofnutrients from the land. The sand bars become
islands with grass and trees that provide cover andnesting sites
for birds. Estuaries are importantnurseries for the young of
aquatic animals. Theyare highly productive because they provide
nutrients washed down from the land in anenvironment that is
sheltered, and shallow enoughto encourage the growth of water
plants
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