Drainage basins.

Question 1

What type of systems are drainage basins?

Answer 1

They are local, open hydrological systems.

Question 2

What actually is a rivers drainage basin? What is this also known as?

Answer 2

A rivers drainage basin is the area surrounding the river where the rain falling on the land flows into that river. This is also known as the rivers catchment.

Question 3

What is the boundary in a drainage system. Where will any precipitation fall beyond the watershed?

Answer 3

This is the watershed - any precipitation falling beyond the watershed enters a different drainage basin (like a different river.)

Question 4

What is the main input into this system and main 3 outputs?

Answer 4

Water mainly enters this system as precipitation and leaves via evaporation, transpiration and river discharge.

Question 5

What are the inputs of water into this system?

Answer 5

The inputs are water coming into this system - this is through precipitation which is all of the moisture from the atmosphere. This is mainly rain but also snow, hail, dew and frost.

Question 6

The first store of water in a drainage basin is interception - what is this?

Answer 6

1) Interception - when some precipitation lands on vegetation or other structures, like buildings and concrete or tarmac surfaces, before it reaches the soil. Interception creates a significant store of water, particularly in wooded areas, however interception storage is very temporary as it is quickly evaporated or falls through vegetation and is infiltrated.

Question 7

What is vegetation storage?

Answer 7

Water that has been absorbed by plants. It is the water contained in plants at any time.

Question 8

What is surface storage?

Answer 8

Water in depressions (Puddles, ponds and lakes). Low lying stores of water on the earths surface.

Question 9

What is soil storage?

Answer 9

All of the moisture in the soil.

Question 10

What is groundwater storage?

Answer 10

Water stored in the ground, either in soil or rocks. The water table is where a lot of the moisture is stored and is the top surface of the zone of saturation - the zone of soil or rock where all the pores in the soil or rock are full of water. Porous rocks that hold water are called aquifers.

Question 11

What is channel storage?

Answer 11

Water stored in rivers or stream channels.

Question 12

What are the 10 flows drainage basins.

Answer 12

Infiltration, Overland flow, Throughfall, Stemflow, Throughflow, Percolation, Groundwater flow, Baseflow, Interflow and Channelflow.

Question 13

What is infiltration?

Answer 13

Water soaking into the soil. Rate of which this occurs depends on soil type, structure and how much water’s already in the soil (saturation.)

Question 14

What is overland flow?

Answer 14

(Runoff) the water flowing over the land. It can flow over the whole surface or in little channels. It happens due to the oversaturation of the ground or rain falling quicker than infiltration rates.

Question 15

What is Throughfall?

Answer 15

Water dripping from one leaf or plant to another.

Question 16

What is stemflow?

Answer 16

Water running down the stem of a plant or a tree trunk.

Question 17

What is throughflow?

Answer 17

Water slowly moving downhill through the soil. It moves fastest down ‘pipes’ - streamlined parts of the soil allowing water to flow optimally, such as cracks in soil or animal burrows.

Question 18

What is percolation?

Answer 18

Water seeping down through the soil into the water table - usually occurs in dryer weather where there has been less saturation.

Question 19

What is groundwater flow?

Answer 19

Water flowing underneath the water table slowly, through permeable rocks. The speed of this occurring depends on the permeability of the rocks beneath the water table - more joints and permeability - quicker (Limestone). Vice versa applies.

Question 20

What is baseflow?

Answer 20

Groundwater flow feeding into rivers through the river beds and banks.

Question 21

What is interflow?

Answer 21

Water flowing downhill through permeable rock above the water table.

Question 22

Channel flow

Answer 22

Water flowing in the river or stream itself. Also called discharge.

Question 23

What are the outputs in a drainage basin.

Answer 23

Evaporation, transpiration, evapotranspiration, river discharge.

Question 24

What is evaporation as an output not a process?

Answer 24

Water turning into water vapour.

Question 25

What is transpiration?

Answer 25

Evaporation from within leaves - plants and trees take up water through their roots and transport it to their leaves where it evaporates into the atmosphere.

Question 26

What is evapotranspiration?

Answer 26

A combination of the two aforementioned outputs. It is the process by which water is transferred from the land surface into vegetation then into the atmosphere as water vapour. It occurs when plants transpire causing the water vapour to escape from their stomata’s, and is then evaporated.

Question 27

What is PET?

Answer 27

PET – potential evapotranspiration is the amount of water that could be lost by this process.

Question 28

What is actual evaporation?

Answer 28

Actual evapotranspiration is what actually happens, for example, in a desert potential evapotranspiration is much higher than the actual amount as there is high temperatures but little vegetation.