Rivers are natural streams of water that flow across the land surface, they shape the landscape by eroding, transporting and depositing their load. In this video, we will learn how rivers do these processes and what features they create along their course. River erosion is the wearing away of the river bed and banks by the force of
water and the abrasion of sediment. River erosion can create features such
as waterfalls, gorges, meanders and oxbow lakes. For example, a waterfall
forms when a river flows over a hard rock layer that is followed by a softer
rock layer. The softer rock erodes faster than the hard rock, creating a steep
drop. Over time, the waterfall retreats upstream, leaving behind a deep valley
called a gorge.
River transport is the movement of sediment along the river by different
methods such as traction, saltation, suspension and solution. The amount and
type of sediment that a river can transport depends on factors such as the
river’s velocity, discharge, gradient and load size. River transport can create
features such as bars, islands and deltas. For example, a delta forms when a
river enters a sea or a lake and deposits its load. The sediment builds up at
the mouth of the river, forming a fan-shaped landform with branches called
distributaries.
River deposition is the dropping of sediment when the river loses its energy or
capacity to transport its load. River deposition can create features such as
floodplains, levees and alluvial fans. For example, a floodplain forms when a
river overflows its banks during a flood and deposits its load on the adjacent
land. The sediment makes the soil fertile and flat, suitable for agriculture. Over
time, the repeated deposition raises the level of the river bed and forms
natural embankments called levees along the banks.
We hope you enjoyed this video and learned something new about rivers. If
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