3. Water Cycle Key Terms

Question 1

Evaporation

Answer 1

The change in state of water from a liquid to a gas.

Question 2

Evapotranspiration

Answer 2

The combined effect of evaporation from vegetation and transpiration.

Question 3

River Discharge

Answer 3

The volume of water flowing through a river channel; measured at any given point in cubic metres per second (cumecs).

Question 4

Interception

Answer 4

When vegetation prevents precipitation from reaching the ground.

Question 5

Soil Water

Answer 5

The amount of water stored in the soil.

Question 6

Surface Water

Answer 6

The water stored on the surface of the Earth, including streams, rivers, lakes, wetlands, reservoirs, and creeks.

Question 7

Ground Water

Answer 7

The amount of water stored in the subsurface pore space of soil and rocks.

Question 8

Channel Storage

Answer 8

The amount of water stored in streams and surface channels

Question 9

Throughfall

Answer 9

The process which describes how wet leaves shed excess water onto the ground surface

Question 10

Stemflow

Answer 10

Water running down a plant stem or tree trunk.

Question 11

[Overland Flow] Surface Runoff

Answer 11

The flow of water that occurs when excess stormwater, meltwater, or other sources flows over the earth’s surface

Question 12

Slope wash / sheet wash

Answer 12

The transportation of rock and soil down a slope by rain

Question 13

Rainsplash

Answer 13

The process where soil particles are knocked into the air by raindrop impact

Question 14

Channel Flow

Answer 14

The flow of water through streams and surface channels

Question 15

Infiltration

Answer 15

The downward movement of water from the surface into the soil.

Question 16

Percolation

Answer 16

The downward movement of water from the soil into the rock beneath.

Question 17

Throughflow

Answer 17

The flow of water downslope within the soil.

Question 18

Groundwater Flow

Answer 18

The deeper movement of water through underlying permeable rock below the water table.

Question 19

Base Flow

Answer 19

The stream discharge produced by water seeping from the bedrock.

Question 20

Water Table

Answer 20

The depth at which all the pores in the rock/soil have been saturated with water

Question 21

Ground Water

Answer 21

The amount of water located in the subsurface pore space of soil and rock

Question 22

Recharge

Answer 22

The replenishment, or renewal, of groundwater in aquifers

Question 23

Springs

Answer 23

Areas where water pressure causes a natural flow of groundwater onto the earth’s surface.

Question 24

Abrasion

Answer 24

Bits of rock and sand scrape against surfaces, grinding them down in a sandpaper-like effect

Question 25

Corrasion | A type of abrasion

Answer 25

A type of abrasion where bedload in the river wears against the bed and banks

Question 26

Attrition

Answer 26

Rocks / Pieces of material crash into each other as they are carried downstream, causing them to break and become smoother

Question 27

Solution

Answer 27

The dissolution of fine sediment by weak acids contained in the river over time, especially chalk and limestone.

Question 28

Cavitation | A type of hydraulic action

Answer 28

A process of hydraulic action where air bubbles trapped in the water get compressed into small spaces like cracks in the river's banks. These bubbles eventually implode creating a small shockwave that weakens the rocks.

Question 29

Hydraulic Action

Answer 29

A process where the water smashes against the river banks, forcing air to become trapped in the cracks of the river bank and bed and the rock to break apart

Question 30

Traction

Answer 30

A process where large material is dragged or rolled along the river bed.

Question 31

Saltation

Answer 31

A process where material bounces along the river bed as it is carried by the current.

Question 32

Suspension

Answer 32

A process where fine material is carried / suspended in the river's current.

Question 33

What is saturated overland flow?

Answer 33

Saturated overland flow is where surface runoff occurs as all the pores of the soil are saturated. ## Footnote This is better than Hortonian flow for reduced flooding - the soil has partly done its job!

Question 34

What is Hortonian flow?

Answer 34

Hortonian flow is where surface runoff occurs as the infiltration capacity of the soil is too low to account for the rainfall intensity. ## Footnote Water is absorbed slower than rainfall, usually because the material is not permeable.