Define global hydrological cycle .

The global hydrological cycle is the continuous movement of water on, above and below the Earth's surface within a closed system .

What is a closed system in the hydrological cycle?

A closed system has no inputs or outputs of matter , only energy crosses its boundary, while stores and flows of water change internally.

True or False? The global hydrological cycle loses water to space.

False. As a closed system , the global hydrological cycle neither gains nor loses water to space; its total water volume stays constant.

In the global hydrological cycle, energy comes from the and is re-radiated from to space.

In the global hydrological cycle, energy comes from the Sun and is re-radiated from Earth to space.

When water , it absorbs energy and cools the surroundings; when it , heat is released.

When water evaporates , it absorbs energy and cools the surroundings; when it condenses , heat is released.

How does gravitational potential energy affect moving water in the cycle?

Water at higher altitude has greater gravitational potential energy , which converts to kinetic energy as it flows downhill, driving surface and channel flow.

Define global water budget .

The global water budget is the balance between inputs and outputs of water across all global stores , considering their sizes and flows .

What is residence time of water in a store?

Residence time is the average time water remains in a particular store before transferring to another part of the hydrological system.

True or False? Increased precipitation always increases water storage in all stores.

False. Intense rainfall can increase surface runoff , reducing infiltration and limiting how much water actually enters and enlarges subsurface stores.

The ITCZ is a migrating low-pressure zone near the with intense .

The ITCZ is a migrating low-pressure zone near the equator with intense rainfall .

Melting of Antarctic and Greenland ice sheets adds water to the and contributes to rising .

Melting of Antarctic and Greenland ice sheets adds water to the oceans and contributes to rising sea levels .

A water store is a body or reservoir of water (such as oceans, ice, groundwater or atmosphere) that temporarily holds water within the hydrological cycle.

Where is most of Earth’s freshwater stored?

Most freshwater is stored as ice in the cryosphere and as groundwater in aquifers , with only a tiny fraction easily accessible to humans.

The flows that transfer water between stores in the hydrological cycle are called .

The flows that transfer water between stores in the hydrological cycle are called fluxes .

Define drainage basin .

An area of land drained by a river and its tributaries , functioning as an open system within the global hydrological cycle .

A boundary line separating one drainage basin from another, usually following high ground such as ridges or hills.

What is the main input to a drainage basin?

The main input is precipitation , including rain, sleet and snow , which adds water to the drainage basin.

True or False? Drainage basins are closed systems .

False. Drainage basins are open systems with inputs (precipitation) and outputs (evaporation, transpiration, river discharge).

In a drainage basin, is water entering soil, while is downward movement through soil and rock.

In a drainage basin, infiltration is water entering soil, while percolation is downward movement through soil and rock.

Define relief (in drainage basins).

The shape and steepness of slopes and overall elevation of the land, which influence runoff and infiltration .

How does steep relief affect surface run off?

Steep relief reduces infiltration and increases surface run off , moving water quickly towards river channels.

True or False? Impermeable soils increase surface run off.

True. Impermeable, saturated, compacted or frozen soils have low infiltration rates , so surface run off is increased.

More cover increases interception, infiltration, drip flow and trunk flow, reducing surface run off.

More vegetation cover increases interception, infiltration, drip flow and trunk flow, reducing surface run off.

Define deforestation (in drainage basins).

The felling and clearance of trees , which reduces interception and infiltration , and increases surface run off and changes in evapotranspiration .

How do urban surfaces affect flood risk?

Impermeable tarmac and concrete reduce infiltration and increase surface run off , while drains move water quickly to rivers, raising flood risk .

What is over-abstraction and its impact on rivers?

Over-abstraction is excessive water removal from rivers or aquifers, causing reduced river flow and lower groundwater levels .

Dams and reduce water flow downstream and increase evaporation due to larger water surface area.

Dams and reservoirs reduce water flow downstream and increase evaporation due to larger water surface area.

Define storm hydrograph .

A storm hydrograph is a graph showing how river discharge responds over time to a single storm event , compared with rainfall during that event.

What two variables does a storm hydrograph compare?

It compares rainfall (in mm , usually bars) and river discharge (in m^3/s , usually a line) over time .

Define lag time on a storm hydrograph.

Lag time is the time difference between peak rainfall and peak discharge on a storm hydrograph.

The limb shows discharge rising to peak; the limb shows discharge falling back to baseflow.

The rising limb shows discharge rising to peak; the recessional limb shows discharge falling back to baseflow.

True or False? A flashy hydrograph has a long lag time and low peak discharge.

False. A flashy hydrograph has a short lag time , steep rising limb and high peak discharge .

Impermeable rock and soils increase surface runoff and make hydrographs more .

Impermeable rock and clay soils increase surface runoff and make hydrographs more flashy .

Larger drainage basins usually have lag times and rising limbs than small basins.

Larger drainage basins usually have longer lag times and gentler rising limbs than small basins.

How does urbanisation affect storm hydrographs?

Urbanisation increases impermeable surfaces and drainage networks , raising surface runoff , peak discharge and making hydrographs more flashy .

Define water balance .

The water balance is the relationship between inputs and outputs of water in a drainage basin, showing any changes in storage .

True or False? In wet seasons, the UK usually has a positive water balance .

True. In wet seasons, precipitation exceeds evapotranspiration , filling stores , increasing runoff and creating a water surplus .

A soil water budget shows the balance between water and in a soil store over a year.

A soil water budget shows the balance between water inputs and outputs in a soil store over a year.

A LevelGeographyEdexcelFlashcardsThe Water Cycle & Water InsecurityHydrological Cycle

Hydrological Cycle (Edexcel A Level Geography): Flashcards

Exam code: 9GE0

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FrontThe Global Hydrological Cycle
Define global hydrological cycle.

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Cards in this collection (39)

Define global hydrological cycle.
The global hydrological cycle is the continuous movement of water on, above and below the Earth's surface within a closed system.
What is a closed system in the hydrological cycle?
A closed system has no inputs or outputs of matter, only energy crosses its boundary, while stores and flows of water change internally.
True or False?
The global hydrological cycle loses water to space.
False.
As a closed system, the global hydrological cycle neither gains nor loses water to space; its total water volume stays constant.
In the global hydrological cycle, energy comes from the and is re-radiated from to space.
In the global hydrological cycle, energy comes from the Sun and is re-radiated from Earth to space.
When water , it absorbs energy and cools the surroundings; when it , heat is released.
When water evaporates, it absorbs energy and cools the surroundings; when it condenses, heat is released.
How does gravitational potential energy affect moving water in the cycle?
Water at higher altitude has greater gravitational potential energy, which converts to kinetic energy as it flows downhill, driving surface and channel flow.
Define global water budget.
The global water budget is the balance between inputs and outputs of water across all global stores, considering their sizes and flows.
What is residence time of water in a store?
Residence time is the average time water remains in a particular store before transferring to another part of the hydrological system.
True or False?
Increased precipitation always increases water storage in all stores.
False.
Intense rainfall can increase surface runoff, reducing infiltration and limiting how much water actually enters and enlarges subsurface stores.
The ITCZ is a migrating low-pressure zone near the with intense .
The ITCZ is a migrating low-pressure zone near the equator with intense rainfall.
Melting of Antarctic and Greenland ice sheets adds water to the and contributes to rising .
Melting of Antarctic and Greenland ice sheets adds water to the oceans and contributes to rising sea levels.
Define water store.
A water store is a body or reservoir of water (such as oceans, ice, groundwater or atmosphere) that temporarily holds water within the hydrological cycle.
Where is most of Earth’s freshwater stored?
Most freshwater is stored as ice in the cryosphere and as groundwater in aquifers, with only a tiny fraction easily accessible to humans.
The flows that transfer water between stores in the hydrological cycle are called .
The flows that transfer water between stores in the hydrological cycle are called fluxes.
Define drainage basin.
An area of land drained by a river and its tributaries, functioning as an open system within the global hydrological cycle.
Define watershed.
A boundary line separating one drainage basin from another, usually following high ground such as ridges or hills.
What is the main input to a drainage basin?
The main input is precipitation, including rain, sleet and snow, which adds water to the drainage basin.
True or False?
Drainage basins are closed systems.
False.
Drainage basins are open systems with inputs (precipitation) and outputs (evaporation, transpiration, river discharge).
In a drainage basin, is water entering soil, while is downward movement through soil and rock.
In a drainage basin, infiltration is water entering soil, while percolation is downward movement through soil and rock.
Define relief (in drainage basins).
The shape and steepness of slopes and overall elevation of the land, which influence runoff and infiltration.
How does steep relief affect surface run off?
Steep relief reduces infiltration and increases surface run off, moving water quickly towards river channels.
True or False?
Impermeable soils increase surface run off.
True.
Impermeable, saturated, compacted or frozen soils have low infiltration rates, so surface run off is increased.
More cover increases interception, infiltration, drip flow and trunk flow, reducing surface run off.
More vegetation cover increases interception, infiltration, drip flow and trunk flow, reducing surface run off.
Define deforestation (in drainage basins).
The felling and clearance of trees, which reduces interception and infiltration, and increases surface run off and changes in evapotranspiration.
How do urban surfaces affect flood risk?
Impermeable tarmac and concrete reduce infiltration and increase surface run off, while drains move water quickly to rivers, raising flood risk.
What is over-abstraction and its impact on rivers?
Over-abstraction is excessive water removal from rivers or aquifers, causing reduced river flow and lower groundwater levels.
Dams and reduce water flow downstream and increase evaporation due to larger water surface area.
Dams and reservoirs reduce water flow downstream and increase evaporation due to larger water surface area.
Define storm hydrograph.
A storm hydrograph is a graph showing how river discharge responds over time to a single storm event, compared with rainfall during that event.
What two variables does a storm hydrograph compare?
It compares rainfall (in mm, usually bars) and river discharge (in m^3/s, usually a line) over time.
Define lag time on a storm hydrograph.
Lag time is the time difference between peak rainfall and peak discharge on a storm hydrograph.
The limb shows discharge rising to peak; the limb shows discharge falling back to baseflow.
The rising limb shows discharge rising to peak; the recessional limb shows discharge falling back to baseflow.
True or False?
A flashy hydrograph has a long lag time and low peak discharge.
False.
A flashy hydrograph has a short lag time, steep rising limb and high peak discharge.
Impermeable rock and soils increase surface runoff and make hydrographs more .
Impermeable rock and clay soils increase surface runoff and make hydrographs more flashy.
Larger drainage basins usually have lag times and rising limbs than small basins.
Larger drainage basins usually have longer lag times and gentler rising limbs than small basins.
How does urbanisation affect storm hydrographs?
Urbanisation increases impermeable surfaces and drainage networks, raising surface runoff, peak discharge and making hydrographs more flashy.
Define water balance.
The water balance is the relationship between inputs and outputs of water in a drainage basin, showing any changes in storage.
What is the water balance equation?
$P = O + E \pm S$
- $P$ = precipitation (mm)
- $O$ = runoff/streamflow (mm)
- $E$ = evapotranspiration (mm)
- $S$ = change in storage (mm)
True or False?
In wet seasons, the UK usually has a positive water balance.
True.
In wet seasons, precipitation exceeds evapotranspiration, filling stores, increasing runoff and creating a water surplus.
A soil water budget shows the balance between water and in a soil store over a year.
A soil water budget shows the balance between water inputs and outputs in a soil store over a year.

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