Freshwater
Completing Your Worksheet
Ok! Below you have four key vocabulary words that deal with how rivers affect the landscape.
Try your best to summarize how these river features are formed on your worksheet.
Reading: pp.13-14
Waterfalls
A waterfall is formed when water flows over an area of land that has different levels of
elevation, creating a drop from one level to another. This usually happens in a river or stream
and can occur for several reasons, one of which is erosion - Water flowing over rock wears it
away over time. Softer rock erodes (wears away) faster than harder rock, creating a drop.
Got it? Watch the video clip for one
more explanation!
Freshwater
Flood Plain
A floodplain is like a natural overflow area for a river, which can help absorb extra water when
the river is too full. Think of it like this, the floodplain is a flat area of land next to a river or
stream that floods when there is more water in the river than it can hold in its usual channel.
Sometimes, especially when it rains a lot or snow melts quickly, a river gets more water than it
can contain within its banks. This excess water overflows onto the surrounding land. This land
(the floodplain) is often made flat because over time, the river brings and leaves behind mud,
sand, and rocks when it overflows. This process makes the land flat and wide.
Please watch this clip. Keep in mind, despite the risk of flooding, these areas are good for
farming because the water brings and leaves behind nutrients in the soil, making it very fertile.
Freshwater
A meandering river is a river that follows a winding path through the landscape.
This process happens over many years and involves several steps and factors.
1. Erosion and Deposition: The
primary forces behind a river's
meandering are erosion and
deposition. As the river flows, it
erodes (wears away) soil and rock
from its banks, especially on the
outside of bends where the water
moves faster. On the inside of
bends, where the water flows more
slowly, it deposits (drops off) the
material it has carried along, like
silt, sand, and pebbles.
2. Formation of Bends: Over time,
these processes exaggerate the
river's natural curves. As the faster-moving water on the outside of a bend erodes more
and more material, and the slower-moving water on the inside deposits more, the bends
become larger and more pronounced. This leads to the formation of meanders, which
are the large loops or curves in the river's path.
3. Cut-offs and Oxbow Lakes: In some cases, a river meander
can become so pronounced that the river creates a new,
shorter path by cutting through a narrow strip of land. This
can leave behind an isolated bend, known as an oxbow lake,
when the river's flow is diverted away from the old loop.
Freshwater
Clip 1: Watch Geologist describes meandering streams, rivers and oxbow lakes. (stop at 1:30)
Clip 2: Watch An Oxbow Lake Form: Ucayali River: 1985 - 2013