Running Water

Day 1

Mass Movements Recap

• Rockfalls– A rockfall occurs when rocks or rock fragments _______

freely through the air• Slides

– In a slide, a _______ of material moves ______________along a flat, inclined surface

– Slides that include segments of bedrock are called rockslides

• Slumps– A slump is the downward movement of a block of material

along a ___________surface

Mass Movement Recap

• Flows– Flows are mass movements of material containing a

large amount of _______– Mudflows move quickly and carry a mixture of soil,

rock, and water that has a consistency of wet concrete

– Earthflows move relatively slowly and carry clay-rich sediment

• Creep is the slow, downhill movement of soil and regolith

Running Water

• The single-most important erosional agent on earth is _____________________.

• But where does the water come from, and how much of it is running, or moving on our planet?

Water Cycle Water is EVERYWHERE

About 97.2 % is in the oceans About 2.15 % is in glaciers and ice sheets About 0.65 % is _______________ in lakes,

streams, groundwater, and the atmosphere

Water constantly moves among the oceans, the atmosphere, the solid Earth, and the biosphere. This unending circulation of Earth’s water supply is the ______________________.

Water Cycle

• How much of our planets water is fresh?

___________

• How does that affect life on our planet?

Water Cycle1. You are already familiar with the Water Cycle -

precipitation , evaporation, infiltration, runoff and transpiration.

- Infiltration – the ____________________________________or soil through cracks and pore spaces.

- Runoff – excess water that does not permeate into the land and _____________________________________instead

Running water starts as precipitation and either infiltrates the surface to flow under ground, or becomes runoff and creates streams and rivers.

Running WaterWhen water falls to Earth it hits the ground running

in the form of ____________and ___________

______________influences how water makes its way to the sea – or base level.

Streams• Water that has become runoff creates streams.• The stream channel is the _________that the water in

a stream follows.

• Streams have different features that will determine how much erosion it causes:1. ______________2. ______________3. Stream ________________4. ______________level

• Let’s take a closer look at each of these features…

Streams - Gradient

• Gradient is the _________or steepness of a stream channel.– Expressed as the vertical drop of a stream channel

over a certain distance.

• Which would move at a higher rate: (highlight)

– A stream with a high gradient, or – A stream with a low gradient?

• Why?______________________________________

Stream Profile

A stream’s ___________is the cross-sectional view of a stream

– From ___________(source) to __________.

• Where would a stream have the steepest gradient – near the head or near the mouth?

• The stream would have a steeper gradient near the _______________.

Streams - Discharge

• A streams discharge is ____________________ ______________in the stream at a given point.– Discharge can vary with snowfall, snowmelt or drought.

• What do you think would happen if a stream’s discharge is increased?– It would go ___________: increased velocity– It would get __________: increased channel width– It would get __________: increased depth

Streams – Base Level

• A base level is the _________________to which a stream can erode.– the level at which the ____________of the

stream enters the ____________, a lake, or another stream

• Two general types– ultimate— ____________level– temporary, or local

Streams – Base Level

• What would happen if you lowered the base level?

• It will cause the stream to ________________.

• Streams mostly head down slope, ultimately reaching it’s final destination – the sea.

Check In Questions1. What is the single most important erosional agent

on earth?2. In the water cycle, what is infiltration in your own

words?3. What happens to a streams discharge as it moves

from the head to the mouth?4. Explain what happens when a stream’s discharge

increases.5. At which part of a stream would the gradient be

steepest?6. What would happen if you lowered the base level of

a stream?