Flow

What is flow?• Flow is materials that move as a

fluid.• The debris is a mixture of rock, soil,

and water moving as a thick liquid.• They can be very devastating.• Examples: mudslides, landslides,

and floods, avalanches

Mudflow• What is a mudflow?• A mudflow is a flow of water that

contains a LARGE amount of suspended particles and silt (being carried in the water).

• Speeds can reach up to 60 mph.• It can take everything in its path.• Boulders as large as houses have

been moved by a mudflow.

Mudslide• How is a mudslide different form a

mudflow?• A mudslide is a mudflow that

occurs on a slope.• They are most common on steep

slopes where there is not enough vegetation to prevent rapid erosion.

Mudslide Pictures

Landslide•Landslides are very similar to

mudflows/slides EXCEPT that they do not involve water.

•It is a dislodging of matter from a hillside that causes a mass of earth and rock to fall.

•Landslides often occur on steep hills.

Weakened Slopes• What causes hills and mountains to

become weakened?• Erosion by rivers, glaciers, or ocean

waves• Fires that leave slopes bare and

vulnerable to rain• Heavy rain or snow that saturate

the ground

Weakened Slopes Con’t

• Structure of the slope weakened by earthquakes

• Loose ash and debris slopes formed by the ash from volcanic eruptions

• Traffic, blasting operations, machinery, and thunder can cause vibrations in weak slopes

• Weight of snow, stockpiling of ores, waste piles, and buildings add stress to weak hillsides.

Where?• Landslides happen in every U.S.

state and territory.• Some areas are more vulnerable:

Rocky Mountains, Appalachian Mountains, and the Pacific Coastal ranges and parts of Alaska and Hawaii.

• Most of these regions have areas of very weak or stressed material resting on steep slopes.

Landslide Pictures

Floods• What is a flood?• Flooding occurs when a river, creek, or

stream overflows its banks and spreads to cover its flood plain.

• Long and heavy rainfall causes flooding.• Flooding can also occur when a river is

blocked by an accumulation of soil, ice, fallen trees, or anything else that diverts water to surrounding areas.

Floods Con’t• Severe flooding can affect

millions of acres of land and force thousands of people to evacuate their homes.

• Several weeks or months may pass before flood waters recede or are absorbed into the ground.

Affect on Soil• The displacement of soil by flood

water not only removes fertile soil from farms, but deposits it in and around homes and businesses, making cleanup an even greater chore.

Flood Pictures

Guiding Question•What can be done to reduce

the impact caused by mudslides, landslides, and floods?