3.1 water in motion
the water cycle
in the short hydrological cycle it moves faster than in the long hydrological cycle. In
the short cycle, the evaporated sea water ends up as precipitation in the same sea or
ocean. During the long cycle, rain, hail or snow ends up on the mainland. In an
extreme case it can take millions of years before the water in ice caps ends up back
in the sea.
the distribution of the water in the cycle
about 70% of the earth is covered in water. but only 1% of this water is drinkable
and reachable for humans. The liquid water on Earth can not only be divided into
fresh and saltwater, but also into surface water and groundwater. surface water is
the water that you can see. for example in oceans and rivers. but there is also water
you can no longer see with the naked eye. It is water that has been drawn in the soil
and rock, you call this groundwater. Of all the fresh water on earth, no less than 69%
is in the form of ice. 8% of the fresh drinking water is in the air in the form of water
vapor.
, 3.2 water in balance
the water balance
The average world citizen needs about 15 million liters of water per year. but not
every human has access to this amount of water by using precipitation only. Luckily
we have other ways to get water. The amount of water that goes in and out of a
country is called water balance. an area can get water in 3 different ways:
1. precipitation precipitation is very unevenly distributed on Earth. In the
Netherlands there are about 660 cubed meters per inhabitant per year. In
Egypt this is only 50 cubed meters, much of that precipitation evaporates
immediately. In warm and dry areas the useful precipitation (the difference
between precipitation and evaporation) is often low.
2. receiving water from other areas for example, in Egypt there is little
precipitation, but the Nile brings a huge amount of water every year to this dry
land.
3. through the supply of fossil water (water from other periods). many areas
have an aquifer, a water based layer in the subsurface that can function as a
‘water piggy bank’
sustainable water management
fresh water is becoming rarer by the day, we have to use it more economically.
Important here is the difference between renewable water sources and non-
renewable water sources. With renewable water, water is always supplemented
(aangevuld) at the pace at which the water is extracted from nature. For example,
when you take water from a river to make it drinking water the river will not run dry.
precipitation creates new river water. when fossil water is used in the desert, this is
often non-renewable water, because the water evaporates faster due to the warm
climate
the water cycle
in the short hydrological cycle it moves faster than in the long hydrological cycle. In
the short cycle, the evaporated sea water ends up as precipitation in the same sea or
ocean. During the long cycle, rain, hail or snow ends up on the mainland. In an
extreme case it can take millions of years before the water in ice caps ends up back
in the sea.
the distribution of the water in the cycle
about 70% of the earth is covered in water. but only 1% of this water is drinkable
and reachable for humans. The liquid water on Earth can not only be divided into
fresh and saltwater, but also into surface water and groundwater. surface water is
the water that you can see. for example in oceans and rivers. but there is also water
you can no longer see with the naked eye. It is water that has been drawn in the soil
and rock, you call this groundwater. Of all the fresh water on earth, no less than 69%
is in the form of ice. 8% of the fresh drinking water is in the air in the form of water
vapor.
, 3.2 water in balance
the water balance
The average world citizen needs about 15 million liters of water per year. but not
every human has access to this amount of water by using precipitation only. Luckily
we have other ways to get water. The amount of water that goes in and out of a
country is called water balance. an area can get water in 3 different ways:
1. precipitation precipitation is very unevenly distributed on Earth. In the
Netherlands there are about 660 cubed meters per inhabitant per year. In
Egypt this is only 50 cubed meters, much of that precipitation evaporates
immediately. In warm and dry areas the useful precipitation (the difference
between precipitation and evaporation) is often low.
2. receiving water from other areas for example, in Egypt there is little
precipitation, but the Nile brings a huge amount of water every year to this dry
land.
3. through the supply of fossil water (water from other periods). many areas
have an aquifer, a water based layer in the subsurface that can function as a
‘water piggy bank’
sustainable water management
fresh water is becoming rarer by the day, we have to use it more economically.
Important here is the difference between renewable water sources and non-
renewable water sources. With renewable water, water is always supplemented
(aangevuld) at the pace at which the water is extracted from nature. For example,
when you take water from a river to make it drinking water the river will not run dry.
precipitation creates new river water. when fossil water is used in the desert, this is
often non-renewable water, because the water evaporates faster due to the warm
climate
