4.1 Introduction to Water Systems

Question 1

Turnover Time

Answer 1

The time taken for a water molecule to enter and leave part of the hydrological system.

Question 2

Advection

Answer 2

The horizontal movement of water in the atmosphere, in vapor, liquid or solid states in air masses - that is, wind - blown movement.

Question 3

Hydrological Cycle

Answer 3

The natural sequence through which water passes into the atmosphere as water vapor, precipitates to Earth in liquid or solid form, and ultimately returns to the atmosphere through evaporation.

Question 4

Evaporation

Answer 4

The process of water in a liquid state changing to a gaseous state (water vapor) due to an increase in temperature.

Question 5

Transpiration

Answer 5

The process by which plants absorb water through the roots and transport it to the leaves from where it is lost as water vapor.

Question 6

Evapotranspiration

Answer 6

The sum of evaporation, sublimation and transpiration from land and ocean surfaces to the atmosphere.

Question 7

Sublimation

Answer 7

The process of changing from a solid to a gas without a liquid phase.

Question 8

Condensation

Answer 8

The process by which water vapor in the air is changed into liquid water.

Question 9

Precipitation

Answer 9

Water that falls to Earth from the atmosphere (e.g. rain, snow, sleet, hail, dew and frost).

Question 10

Green Water

Answer 10

The proportion of total precipitation absorbed by soil and plants, then released back into the air.

Question 11

Blue Water

Answer 11

The proportion of precipitation that collects in water courses (in rivers, lakes, wetlands and as groundwater) and is available for human consumption.

Question 12

Surface Runoff

Answer 12

The soil is unable to take in any more water, therefore the rain flows on the surface under the influence of gravity.

Question 13

Throughflow

Answer 13

Water flowing through the soil.

Question 14

Infiltration

Answer 14

The passage of water into the soil.

Question 15

Percolation

Answer 15

The downward vertical movement of water within a soil or rock.

Question 16

Hydrograph

Answer 16

A graph showing the rate of flow (discharge) over a certain period past a specific point in a river. The rate of flow is expressed in cubic meters per second.

Question 17

Flash Flood

Answer 17

A flood caused by heavy or excessive rainfall in a short period, generally less than six hours. Raging torrents of water can rip through river beds, urban streets or mountain canyons, sweeping everything before them. They can occur after minutes or a few hours of excessive rainfall.

Question 18

Upwelling

Answer 18

Winds blowing across the ocean surface often push water away from an area. When this occurs, water rises up from beneath the surface to replace the diverging surface water.