4.4 The Power of Water Flashcards
How can water affect it’s surroundings?
Erosion, Flooding, Avalanches and Landslides.
What is sediment?
Sediment is material such as sand, silt and mud that is carried and deposited by wind, water or ice.
What are the effect of sediment?
Less oxygen due to less light, temperature changes and shallower water due to soil settling.
How does vegetation help with sediment?
Vegetation helps with sediment because the roots hold down soil so that it can’t be moved. Leaves also protect the soil from rain and prevent splash erosion.
How does farming contribute to sediment?
Ploughing farmland removes vegetation for short term periods and clear-cut logging for a longer period. Farmer sometimes let weeds grow in fields that are not being used so that the roots can hold down soil.
What is clear-cut logging?
The cutting of all trees over a large area.
What is contour ploughing and how does it help?
Ploughing across the slope of the hill will help retain the soil in farm fields.
What is deposition?
Deposition is when sediment begins to settle on the bottom of the body of water. Heavier particles settle first and sand and silt are carried farther away.
What is dredging?
Removing bottom sediment to help with the water levels.
What causes floods?
Excessive rainfall or rough waves. Or dam burst which are rare.
What are levees?
Levees are walls of earth that are built along the banks parallel to a river. They are designed to keep a river contained during flooding.
What are dikes?
Dikes protect land that has been reclaimed from the ocean. They are also built around houses or towns when floods threaten.
What is an avalanche?
An avalanche is like a landslide but with snow.
How does the expanding and contracting of water cause avalanches?
Water gets into the crack and freezes which means it expands. The water melts and more water comes in and expands. The crack gets bigger, the more it expands until it falls. Because of repeating freezing and thawing which expands the crack and eventually breaks off from the mountain
How do patrols deal with avalanches?
Blow it Up!
