What is a drainage basin? How is it different to the global hydrological cycle?

Question 1

What is a drainage basin?

Answer 1

An area of land drained by a river and its tributaries (river system).

Question 2

What kind of systems are drainage basins?

Answer 2

local open systems

Question 3

How are drainage basins cascading systems?

Answer 3

One drainage basin’s outputs are the inputs to another.

Question 4

What is a watershed?

Answer 4

A ridge of high land separating drainage basins.

Question 5

What is a river?

Answer 5

A large natural stream of water flowing in a channel to the sea, a lake or another river.

Question 6

What is a confluence?

Answer 6

The junction of two rivers of approximately equal width.

Question 7

What is a tributary?

Answer 7

A river or stream flowing into a larger river or lake.

Question 8

What is a mouth?

Answer 8

The point where the river comes to an end, usually when entering the sea or ocean

Question 9

What is a source?

Answer 9

The original point from which a river flows.

Question 10

Define interception storage

Answer 10

When precipitation lands on buildings, vegetation and concrete before it reaches the soil.

Question 11

Define vegetation storage

Answer 11

Any water taken up by vegetation which is held within plants.

Question 12

Define surface storage.

Answer 12

The total volume of water held on the earth’s surface in lakes, ponds and puddles.

Question 13

Define groundwater storage.

Answer 13

The storage of water underground in permeable rock strata.

Question 14

Define throughflow.

Answer 14

The movement of water flowing downhill through permeable rock above the water table.

Question 15

Define channel flow

Answer 15

The movement of water within the river channel, known also as river discharge.

Question 16

Define ground water flow.

Answer 16

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

Question 17

Define infiltration.

Answer 17

The downwards movement of water into the soil surface.

Question 18

Define percolation

Answer 18

The downwards flow of water within the soil due to gravity.

Question 19

Define stem flow

Answer 19

The movement of water running down a plant stem or tree trunk.

Question 20

Define throughfall

Answer 20

Any precipitation which penetrates through the canopy and reaches the soil surface by canopy drip.

Question 21

Define runoff

Answer 21

The movement of water over the surface of the land (usually if the ground is too saturated or frozen).

Question 22

Define evaporation

Answer 22

The transformation of water droplets into water vapour by heating.

Question 23

Define evapotranspiration

Answer 23

The loss of water from the drainage basin into the atmosphere from the leaves of plants and other surfaces by heating.

Question 24

Define transpiration

Answer 24

Evaporation of water from plant leaves.

Question 25

Define discharge.

Answer 25

The amount of water that passes a given point in a given amount of time.

Question 26

Describe the characteristics of a temperate coniferous forest. How do these characteristics affect stemflow and interception separately?

Answer 26

1. Mishapen and curved tree shape, can have a wide trunk, canopy is more open.
2. Interception - reduced since the canopy has more gaps (increased SR)
3. Stemflow - slow and reduced by the nature of the trunk (reduced SR)

Question 27

Describe the characteristics of a temperate deciduous forest. How do these characteristics affect stemflow and interception separately?

Answer 27

1. Straight stems and dense canopy
2. Interception - increased due to dense canopy (reduced SR)
3. Stemflow - increased since water movement is aided by gravity and trunk shape (increased SR)

Question 28

How might throughflow vary in different ecosystems?

Answer 28

1. Coarse, sandy soil absorbs and transfers water rapidly, increasing the speed of throughflow
2. Clay soils drain more slowly and have a high field capacity (lots of water is retained in soil storage), decreasing the speed of throughflow

Question 29

How might groundwater flow vary in different ecosystems?

Answer 29

1. If the bedrock is impermeable, no further downward movement of water occurs (less groundwater flow)
2. If the bedrock is permeable, water will seep into cracks in the rock and slowly pass through (increased groundwater flow)

Question 30

Give an example of a permeable rock.

Answer 30

limestone

Question 31

Compare the flow rate of sandstone with the flow rate of unconsolidated gravel.

Answer 31

Sandstone - 200cm per hour (less permeable
Unconsolidated gravels - 20,000cm per hour (more permeable)

Question 32

Give an example of a positive feedback in the water cycle.

Answer 32

1. Sea levels rise due to thermal expansion and ice melt
2. Ice shelves become unstable, leading to increased carving
3. Ice melt increases, sea levels rise again.

Question 33

Give an example of a negative feedback in the water cycle.

Answer 33

1. Increased surface temperatures increases evaporation from oceans
2. Increased cloud cover
3. Clouds reflect the sunlight and cause a reduction in surface temperatures
4. Reduced evaporation.

Question 34

What is the difference between the drainage basin and the hydrological cycle in terms of systems?

Answer 34

A drainage basin is an open system where the inputs and output can change whereas the hydrological cycle is a closed system so no water enter or leaves the system.

Question 35

Give two factors which can impact the dynamic equilibrium in a drainage basin.

Answer 35

1. Human activity (e.g modifying the drainage basin)
2. Extreme events like storms or droughts