Water cycle:
 The water cycle is also known as the hydrological cycle.
 It is called a cycle because water continuously moves around the
system. Rivers are part of this cycle.
 Water goes through three different stages in the water cycle
 It can be a liquid (water), a gas (water vapour) or a soild (ice)
 These three states are interchangeable, as water can freeze into
ice or evaporate into water vapour, water vapour can condense as
water, and ice can melt into water
How does the water cycle work?
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Energy from the Sun heats the surface of the Earth.
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Water is evaporated from oceans, rivers, lakes, etc.
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The warm, moist air rises because it is less dense.
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Condensation occurs when water vapour is turned back into water
droplets as it cools down. Clouds are formed.
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Precipitation occurs as water droplets get bigger and heavier they
begin to fall as rain, snow and sleet, etc.
When the precipitation reaches the surface, some falls directly into the
sea but other water falls on land:

Some water is intercepted by vegetation. Some water may then
slowly reach the ground. Some will evaporate from the surface of
leaves or be taken up by the plant roots, and some of this water will
eventually return to the air as vapour through the process of
transpiration. This slows down or prevents some water flowing back
to the river.
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Some water flows across the surface of the ground - surface run-off.
This happens when the surface doesn't allow water to penetrate.
Surface run-off is more likely to occur if the ground is saturated with
water or when the rock is impermeable. This water moves quickly to
the river.

Some water infiltrates into the soil. This through flow moves more
slowly back to the river than surface run-off.

Some water percolates deeper into the ground and is slowly
transferred back to the river or sea.
The water cycle process is driven by sun
Evaporation:
Evaporation is the process of liquid water’s (ocean, lakes, or rivers)
surface changing to a gas (becomes water vapour)
In shortly - Water is heated by the sun and turns into water vapour
Condensation:
 It is the process when gas is changing into a liquid
 In water cycle, water vapour in the atmosphere condenses and
becomes liquid
 Clouds form as water vapour condenses or becomes more
concentrated (dense)
 Then, water vapour condenses around tiny particles called as
cloud condensation nuclei (CCN)
 CCN can be flecks of dust, salt, or pollutants
Precipitation:
 Water returning to the ground as rain, sleet or snow
 Precipitation reaches the river by infiltration – seeps down
through spaces in the soil, reaches permeable rock and flow or
passes through gaps or pores within the rock
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In some areas precipitation reaches the river more quickly
because,
Down valley side slope speeding up surface runoff
Less surface resistance of flow over the agriculture land especially
where the field is ploughed down the slope
In some areas precipitation reaches the river more slowly
because,
Large area of woodland at the top of slope to intercept rain
Interception reduces runoff because of deforestation
Permeable rock under the soil so that some can penetrate
underground
Surface run-off:
 It is where water flows downhill across the surface
 Surface run-off helps move elements(C, N, P, S) from terrestrial,
land-based to aquatic ecosystems
 If trees were cleared and tourist resort built, the run-off would
increase or no interception by leaves or stem (trees), therefore no
absorption by roots concrete or surface not absorb
Transpiration:
 It is the process by which plants lose water out of their leaves
 It is important in the water cycle because plants absorb the
moisture from the soil and release it into the atmosphere as
water vapour
Interception
 Water is stoped from reaching the ground by trees and plants.
 It will propably be reduced after deforestation, because thre will
be less vegetation to trap or intercept the rainwater
Infilteration:
 It refers to water sinking into to the soil
 It is the downward movement of water from the land surface into
the soil or porous rock
Percolation:
 Rainfall seeps underground through a process called percolation,
where water travels downwards through the tiny spaces between
rocks and soil particles due to the force of gravity
 The water eventually saturates the underlying rock much like
water fills the tiny holes of sponge. This helps to replenish
aquifers under the ground