River erosion and landforms.
River erosion is a very important part of water erosion. Rivers are natural channels that carry
water from its source to lakes, other rivers, seas and so on. A water source is a geographic
spot where moving water begins, such as a mountain top or a spring. The speed, behavior
and erosive power of rivers are different at various stages of the river. What rivers do to the
land also depends on the type of rock that the land is made of.
Consider this illustration:
For example, from the mountain top, rivers flow very fast because the slopes of the mountains
are steeper. The water is also narrower and has high erosive power. This means they are able
to cut through the rocks on which they flow. Rapids, waterfalls and v-shaped valleys are common
along the path of rivers upstream.
Down at the foot of the mountains and where the rivers end (such as an estuary or the sea)
the rivers are slow flowing with lots of curves. They contain a lot of sediments that begin to
settle. This means that landforms created by water erosion will be different at these two
stages of the river.
Consider this illustration below:
From the above, you will notice that landforms with steeper valleys, waterfalls and gorges
are more likely to form at the upper regions of highlands or mountains. This is so because the
power of the river is higher and does more erosion or carving than it deposits. Landforms at the
end of rivers are more sediment deposited landforms such as moraines, flood plains, deltas
and estuaries. This is so because the rivers have lost their erosive and transporting power
and are depositing the load now. A river's load is all the stuff it carries such as fine sand,
silt and clay, small tree stumps and vegetative matter and so on.