135
Almost 71% of the surface of Earth is covered
by oceans and the hydrosphere is composed by
terrestrial surface and subsurface waters as well,
including inland ice sheets and glaciers and also
the water content of the atmosphere. Water is a
universal solvent although it solves different
materials in very different grades. Any natural
material may move with waterflow in dissolved,
suspended or rolled state. Water also provides
habitats for certain living beings (aquatic living
beings) and is involved in the metabolism of all
living creatures. It forms the second basic material of photosynthesis and O 2 molecules formed
in the process out of the oxygen of water are
released from the body of plants into the atmosphere. (This process resulted in the increase of
the amount of atmospheric oxygen in the geological past).
The uniquely high heat capacity of water
makes the hydrosphere an enormous heat energy
reservoir playing a major role in shaping the climatic system of the planet. Water has a greater
evaporation and freezing heat as well than most
liquids and these properties influence the
climate.
Basically two types of energies determine
water movement in nature: the heat energy of
solar radiation triggering evaporation (the active
water intake and evaporation of plants also plays
a role in this) and gravitation that results in the
falling of precipitation and running water on the
surface. Horizontal atmospheric water transport
includes water vapour and clouds moved by
wind—and the energy required by these is provided by the heat energy of solar radiation.
The water cycle is started by evaporation triggered by solar radiation. Evaporation intensities
of oceans and dry lands are different and the former is greater. Most scientists agree in this, however, estimated values differ greatly (Shiklomanov
1993; Manning 1997; Henshaw et al. 2000;
Shiklomanov and Rodda 2003; Trenberth et al.
2007; Rodell et al. 2015). Some scientist developed hydrological models as well (Güntner 2008;
Sood and Smakhtin 2015). Research using modern methods made the determination of the volume of fluxes (amount of water transported over a
unit period of time) in the global water cycle
more accurate. Rodell et al. (2015) estimated the
average annual and monthly fluxes in the first
decade of the twenty-first century based on satellite measurements and data-integrating models.
Water and energy budgets were considered in the
calculations. An optimised algorithm was used
for estimating the water flux. Figure 4.48 presents these optimised data. Uncertainties of estimations were also discussed. The standard
deviation of the data varied around 5% only that
of global runoff was greater (9.5%).
The amount of water stored in global reservoirs is presented on the basis of the data of
Shiklomanov (1993) and Shiklomanov and
Rodda (2003) accepted by the US Geological
Survey noting that the data of Trenberth et al.
(2007) differ significantly only in the cases of
groundwater and permafrost due to different definitions. (The topic will be mentioned again in
Sect. 4.3.3.) The data presented in Table 4.9 are
more differentiated. Fluxes are presented in
Fig. 4.48. The authors note that no significant differences can be found in the opinion of different
authors regarding the analysis of the processes of
the cycle and the evaluation of anthropogenic
effects.
The largest water reservoir in the planet is the
world ocean in which 96.5% of the hydrosphere
is stored. On average 449,500 km
3
water is evaporated via its surface each year and 403,500 km
3
precipitation falls back (Fig. 4.48). This would be
a significant loss if rivers (46,000 km
3
) and to a
smaller extent groundwater (2000 km
3
) did not
replenish oceans. Precipitation falling onto the
continents is 116,500 km
3
which is 46,000 km
3
more than the evaporated water. Evaporation of
terrestrial areas is made of the direct evaporation
of soil and rock surfaces and the transpiration of
plants (called evapotranspiration together).
Figure 4.48 shows that atmosphere is the smallest
water reservoir (12,900 km
3
) while transporting
486,000 km
3
of water in the forms of cloud and
moisture. This also means that the complete
water content of the atmosphere is exchanged in
10 days.
Considering water use of the society terrestrial
fresh water reservoirs have to be studied since
these can be used as potable water, industrial
4.3 Changes in the Hydrosphere
Almost 71% of the surface of Earth is covered
by oceans and the hydrosphere is composed by
terrestrial surface and subsurface waters as well,
including inland ice sheets and glaciers and also
the water content of the atmosphere. Water is a
universal solvent although it solves different
materials in very different grades. Any natural
material may move with waterflow in dissolved,
suspended or rolled state. Water also provides
habitats for certain living beings (aquatic living
beings) and is involved in the metabolism of all
living creatures. It forms the second basic material of photosynthesis and O 2 molecules formed
in the process out of the oxygen of water are
released from the body of plants into the atmosphere. (This process resulted in the increase of
the amount of atmospheric oxygen in the geological past).
The uniquely high heat capacity of water
makes the hydrosphere an enormous heat energy
reservoir playing a major role in shaping the climatic system of the planet. Water has a greater
evaporation and freezing heat as well than most
liquids and these properties influence the
climate.
Basically two types of energies determine
water movement in nature: the heat energy of
solar radiation triggering evaporation (the active
water intake and evaporation of plants also plays
a role in this) and gravitation that results in the
falling of precipitation and running water on the
surface. Horizontal atmospheric water transport
includes water vapour and clouds moved by
wind—and the energy required by these is provided by the heat energy of solar radiation.
The water cycle is started by evaporation triggered by solar radiation. Evaporation intensities
of oceans and dry lands are different and the former is greater. Most scientists agree in this, however, estimated values differ greatly (Shiklomanov
1993; Manning 1997; Henshaw et al. 2000;
Shiklomanov and Rodda 2003; Trenberth et al.
2007; Rodell et al. 2015). Some scientist developed hydrological models as well (Güntner 2008;
Sood and Smakhtin 2015). Research using modern methods made the determination of the volume of fluxes (amount of water transported over a
unit period of time) in the global water cycle
more accurate. Rodell et al. (2015) estimated the
average annual and monthly fluxes in the first
decade of the twenty-first century based on satellite measurements and data-integrating models.
Water and energy budgets were considered in the
calculations. An optimised algorithm was used
for estimating the water flux. Figure 4.48 presents these optimised data. Uncertainties of estimations were also discussed. The standard
deviation of the data varied around 5% only that
of global runoff was greater (9.5%).
The amount of water stored in global reservoirs is presented on the basis of the data of
Shiklomanov (1993) and Shiklomanov and
Rodda (2003) accepted by the US Geological
Survey noting that the data of Trenberth et al.
(2007) differ significantly only in the cases of
groundwater and permafrost due to different definitions. (The topic will be mentioned again in
Sect. 4.3.3.) The data presented in Table 4.9 are
more differentiated. Fluxes are presented in
Fig. 4.48. The authors note that no significant differences can be found in the opinion of different
authors regarding the analysis of the processes of
the cycle and the evaluation of anthropogenic
effects.
The largest water reservoir in the planet is the
world ocean in which 96.5% of the hydrosphere
is stored. On average 449,500 km
3
water is evaporated via its surface each year and 403,500 km
3
precipitation falls back (Fig. 4.48). This would be
a significant loss if rivers (46,000 km
3
) and to a
smaller extent groundwater (2000 km
3
) did not
replenish oceans. Precipitation falling onto the
continents is 116,500 km
3
which is 46,000 km
3
more than the evaporated water. Evaporation of
terrestrial areas is made of the direct evaporation
of soil and rock surfaces and the transpiration of
plants (called evapotranspiration together).
Figure 4.48 shows that atmosphere is the smallest
water reservoir (12,900 km
3
) while transporting
486,000 km
3
of water in the forms of cloud and
moisture. This also means that the complete
water content of the atmosphere is exchanged in
10 days.
Considering water use of the society terrestrial
fresh water reservoirs have to be studied since
these can be used as potable water, industrial
4.3 Changes in the Hydrosphere