Geography T1 - Hydrological cycle

What is the hydrological cycle?

the global movement of water between the air, land and sea.

Key terms required for the exam:

aquifer, evaporation, transpiration, evapotranspiration, condensation, precipitation, stem flow, surface run off, infiltration, percolation, groundwater, groundwater flow, through flow

What are stores?

features such as seas, lakes, rivers, glaciers and aquifers that receive, hold and release water.

What are flows/transfers?

the movement of water between stores

What are the characteristics of the hydrological cycle?

it has inputs, transfers/flows, stores and outputs

1.It is a closed system (no EXTERNAL inputs and outputs) and a global cycle.
2. Within this system, water changes its state and can be seen in solid, liquid and gaseous form.
3. Within the hydrological cycle there are (internal) inputs, transfers/flows, stores and outputs.
4. The input is precipitation (rainfall or snowfall)
5. The main output is river discharge but evapotranspiration is also an output.
6. The transfers or flows are surface run-off/overland flow, infiltration, percolation, groundwater flow and through flow. Within the cycle water flows as a liquid from store to store.
7. The stores on land are rivers, lakes, ice, soil, vegetation and groundwater. Other stores include seas, oceans and the atmosphere.

How stores can be grouped:

1. Atmosphere – water exists as water vapour (when it evaporates) or as tiny droplets in clouds.
2. Land – water is stored (a) on the surface in rivers, lakes and reservoirs
(b) taken by plants and stored in vegetation
(c) and below ground in the bedrock as groundwater store: water mostly exists in liquid form, but here, it can also exist in solid form in ice sheets, glaciers and snowfields.
3. Sea – over 95% of the Earths’ water is stored in the sea, mostly in liquid form, but also as ice (ice bergs) in high altitude seas.

How transfers of water between stores take place through a variety of flows:

1. Evaporation
2. Transpiration
3. Evapotranspiration
4. Condensation
5. Precipitation
6. Overland flow
7. Infiltration and percolation
8. Throughflow
9. Groundwater flow

Can the amount of water in the global water cycle change?

No

Can the proportion held in different stores at different times change?

Yes

Does the sun play a huge role in the hydrological cycle?

Yes

Does all the water that falls as rain reach the sea?

Yes

What is the water table?

It is the upper level of an underground surface in which the soil or rocks are permanently saturated with water.