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Chapter 11
Rivers & Groundwater
11.1 Notes – The Active River
Water Cycle
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
water cycle – the continuous movement of
water from water sources, into the air, on to
land, into the ground, and back to water sources
evaporation – liquid water from water sources
changes into water vapor in the air due to heat
from the sun
condensation – water vapor in the air changes
into liquid droplets, forming clouds
11.1 Notes – The Active River
Water Cycle
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precipitation – rain, snow, sleet, or hail
falls from the clouds on to the Earth’s
surface
percolation – gravity pulls water that is
already in the ground through the soil back
to the water sources
11.1 Notes – The Active River
Water Cycle

runoff – water flows across the ground or
falls from the clouds and collects in rivers
or streams
11.1 Notes – The Active River
Water Cycle

What main source of energy drives Earth’s
weather systems?


Solar radiation (from the sun)
What drives the water cycle?

The sun

weathering – the process by which
sediment is broken off rock

erosion – the process by which sediment is
picked up and moved to a new location
Erosion

What are the 5 agents of erosion?
1.
2.
3.
4.
5.
Wind
Water (rivers, streams, ocean waves)
Ice (glaciers)
Precipitation (rain, snow, sleet, & hail)
Gravity (causes landslides)
Erosion

How can erosion happen fast?


A river overflowing leaving the side of the
banks muddy
How can erosion happen slowly?

Grand Canyon – the river eroding the surface
of the Earth slowly overtime

deposition – the process by which sediment
is dropped due to lack of speed
Mountain Changes

What can change the shape of a mountain?


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

Precipitation – rain, snow, sleet, and hail
Runoff – forming rivers and streams
Water flowing down hill can carry sediment because of
gravity
Weathering, erosion, & deposition
What will form at the top of a mountain during
precipitation?

A stream with a few bends
11.1 Notes – The Active River
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load – the rocks and soil (sediment) carried in a stream’s
water
Why would a river carry more of a load?


Because it has more water, because it is flowing fast, because it
is on a hill or mountain, because water in a river can rise during
precipitation
3 types of loads:
1. bed load – large pieces of sediment like boulders and
pebbles
2. suspended load – small pieces of sediment like small
rocks and sand – this makes the water look muddy
3. dissolved load – dissolved material like sodium and
calcium – this makes the water look clear
11.1 Notes – The Active River
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
meander – a curve or bend in a river or
stream
What happens at a meander?
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
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On the outside of the curve the water speeds
up and erodes sediment
On the inside of the curve the water slows
down and deposits sediment
channel – the path that a stream follows
Characteristics of the
4 stages of a river

youthful river – fast, waterfalls, steep
gradient, bedload, deep not wide, erosion
happens quickly
Characteristics of the
4 stages of a river

mature river – deep, slow, wide, not very
steep, meanders, suspended load
Characteristics of the
4 stages of a river

old river – slow, wide, shallow, floods,
meanders, dissolved load, a lot of sediment
deposits, many times forms oxbow lakes
• oxbow lake – formed
by an increase in
the flow of water in a
river causing the river
to change course
Characteristics of the
4 stages of a river

rejuvenated river – land is raised by
tectonic plates, steep cliffs above the river,
river erodes valley floor
11.1 Notes – The Active River

Why would one river have more sediment than
another river?
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What would give a river more water?
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More water = more sediment
precipitation
What are two ways that beaches get sand?
1.
2.
Waves slow down and weather rocks depositing sand
Rivers end at the ocean creating a delta (deposited
sediment)
11.1 Notes – The Active River

Why does water flow downhill on a mountain?


Gravity – water always flows from higher elevations to
lower elevations
How do you know if a river has recently flooded?

There is wet mud on the ground
11.1 Notes – The Active River

How could two mountains with a small stream in
between become flat 50 million years later?


What happened to the sediment?
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
precipitation
eroded by the stream and deposited in the ocean
Why would a river change course?

floods
11.2
Stream
and River
Deposits
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
alluvial fan – fan shaped deposits that form on
dry land when a river or stream loses speed
delta – fan shaped deposits that form at large
bodies of water such as the ocean when a river
or stream loses speed

This is one way beaches more sand.
11.2 Stream and River Deposits

floodplains – an area along a river that
forms from sediment deposited when a
river overflows its banks

Where would you find a lot of floodplains?

On old rivers because they flood a lot