Chapter 11

Rivers & Groundwater

11.1 Notes – The Active RiverWater Cycle

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 RiverWater Cycle

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 RiverWater Cycle

runoff – water flows across the ground or falls from the clouds and collects in rivers or streams

11.1 Notes – The Active RiverWater 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. Wind

2. Water (rivers, streams, ocean waves)

3. Ice (glaciers)

4. Precipitation (rain, snow, sleet, & hail)

5. 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?

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 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

pebbles2. suspended load – small pieces of sediment like small

rocks and sand – this makes the water look muddy3. dissolved load – dissolved material like sodium and

calcium – this makes the water look clear

11.1 Notes – The Active River meander – a curve or bend in a river or

stream What happens at a meander?

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? More water = more sediment

What would give a river more water? precipitation

What are two ways that beaches get sand?1. Waves slow down and weather rocks depositing sand

2. 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? precipitation

What happened to the sediment? eroded by the stream and deposited in the ocean

Why would a river change course? floods

11.2 Stream

and RiverDeposits

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