Hydrosphere

Question 1

What is Hydraulic Action?

Answer 1

When the force of water compresses ait and pressure on the banks causes material to be dislodged.

Question 2

What is Abrasion?

Answer 2

When the force of water throws the bedload against the banks wearing them down.

Question 3

What is Solution?

Answer 3

When soluble rocks react with acids or salts in the water.

Question 4

What is Attrition?

Answer 4

When rocks in suspension hit off eachother eroding further.

Question 5

Describe the formation of a V-shaped Valley.

Answer 5

• V-shaped valleys form in the upper courses of rivers where the land is often steep and rivers have high energy.
• This causes vertical erosion to dominate through Hydraulic Action and Abrasion.
• Hydraulic action is when the force of water compresses ait and pressure on the banks causes material to be dislodged.
• Abrasion is when the force of water throws the bedload against the banks wearing them down.
• Weathering causes the rocks and soils to break down on the sides of the valley. This happens quicker in colder, wetter areas.
• The hillslopes become unstable causing a mass movement (landslide) and the material falls into the river channel.
• Here it is broken up by attrition and used as a tool for further erosion.
• A narrow valley is left with the river filling the whole valley floor.
• The river continues to zigzag down its course through interlocking spurs.

Question 6

Describe the formation of a waterfall.

Answer 6

• Waterfalls form in the upper course of rivers where there is a band of hard rock overlaying soft rock.
• This causes differential erosion as the rocks are eroded at different rates through Hydraulic action and Abrasion.
• Hydraulic action is when the force of water compresses ait and pressure on the banks causes material to be dislodged.
• Abrasion is when the force of water throws the bedload against the banks wearing them down.
• Softer rock is eroded more easily creating an overhang of hard rock as it is undercut.
• The hard rock becomes unsupported and collapses into the plunge pool due to gravity.
• Material is broken up by attrition and used as a tool for further erosion.
• This process repeats itself the waterfall retreats upstream creating a gorge.

Question 7

What is Traction?

Answer 7

Large boulders and rocks are rolled along the river bed.

Question 8

What is Saltation?

Answer 8

Small pebbles and stones are bounced along the river bed.

Question 9

What is Suspension?

Answer 9

Fine, light materials are carried along the river.

Question 10

Describe the formation of a Meander.

Answer 10

• Meanders form in the middle to lower course of rivers where water twists and turns around obstructions like large boulders or trees.
• The river starts to become more sinuous as riffles and pools lead to changes in speed, depth and direction of the river channel.
• Pools are areas of deeper water whereas riffles are shallower with greater turbulence where lateral erosion can occur through Hydraulic action and Abrasion.
• Hydraulic action is when the force of water compresses ait and pressure on the banks causes material to be dislodged.
• Abrasion is when the force of water throws the bedload against the banks wearing them down.
• The river flows fastest on the outside bend increasing erosive power.
• The river flows slowest on the inside bend leading to deposition.
• Helicoidal flow moves materials across the river channel. This leads to the development of river cliffs on the outside bend and beaches on the inside.
• As erosion and deposition continue the meander will migrate downstream.

Question 11

Describe the formation of an Ox-bow lake.

Answer 11

• Meanders form in the middle to lower course of rivers where water twists and turns around obstructions like large boulders or trees.
• The river starts to become more sinuous as riffles and pools lead to changes in speed, depth and direction of the river channel.
• Pools are areas of deeper water whereas riffles are shallower with greater turbulence where lateral erosion can occur through Hydraulic action and Abrasion.
• Hydraulic action is when the force of water compresses ait and pressure on the banks causes material to be dislodged.
• Abrasion is when the force of water throws the bedload against the banks wearing them down.
• The river flows fastest on the outside bend increasing erosive power.
• The river flows slowest on the inside bend leading to deposition.
• Helicoidal flow moves materials across the river channel. This leads to the development of river cliffs on the outside bend and beaches on the inside.
  As erosion and deposition continue the meander will migrate downstream.
  Over time, meanders become more pronounced.
• The neck of the meander will become narrower as it is eroded.
• During a time of high energy (for example a flood or during spring when snow is melting), the water may cut through the neck of the meander.
• Deposition on the rivers banks seal off the old meander, so water no longer flows around it.
• This is called an Ox-bow lake.

Question 12

Inputs into a drainage basin.

Answer 12

Precipitation is all forms of moisture that reach the earths surface and is the only input into a drainage basin. Examples of precipitation include rain, snow, sleet etc.

Question 13

How is water transferred through a drainage basin?

Answer 13

• Stemflow - when water moves down the stems or trunks of trees and plants.
• Surface run off - when water moves across the earths surface due to gravity
• Infiltration - when water moves down through the soil
• Percolation - when water moves through the rocks below the soil

Question 14

How is water stored in a drainage basin?

Answer 14

• Interception - when precipitation is intercepted by vegetation slowing down the movement of water.
• Surface water - when water is stored in puddles, reservoirs, lochs or ponds.
• Soil moisture - When water is held in upper layers of the soil profile.
• Groundwater - when water is stored naturally underground in the spaces between rocks/soil forming the water table.