Geoscience Reference
In-Depth Information
Table 1.2 Some estimates of the mean precipitation (and river runoff) from available data for the continents
(inmy
-1
)(
∗
)
Australia
and
North
South
Europe
Asia
Africa
America
America
Oceania
Antarctica
Percent of land area
6.7
29.6
20.0
16.2
12.0
6.0
9.5
Reference
Lvovitch (1973)
0.734
0.726
0.686
0.670
1.648
0.736
−
(0.319)
(0.293)
(0.139)
(0.287)
(0.583)
(0.226)
−
Baumgartner and
0.657
0.696
0.696
0.645
1.564
0.803
0.169
Reichel (1975)
(0.282)
(0.276)
(0.114)
(0.242)
(0.618)
(0.269)
(0.141)
Korzoun
et al
.
0.790
0.740
0.740
0.756
1.600
0.791
0.165
(1977)
(0.283)
(0.324)
(0.153)
(0.339)
(0.685)
(0.280)
(0.165)
∗
The corresponding evaporation values can be determined with Equation (1.1).
Table 1.3 Estimates of different forms of global water storage (as depth in m over entire earth surface)
Lvovitch
Baumgartner and
Source of data
(1970)
Reichel (1975)
Korzun
et al
. (1978)
Oceans
2686
2643
2624
Ice caps and glaciers
47.1
54.7
47.2
Total ground water
117.6
15.73
45.9
(excluding Antarctica)
(Active ground water)
(7.84)
(6.98)
—
Soil water
0.161
0.120
0.0323
Lakes
0.451
0.248
0.346
Rivers
0.002 35
0.002 12
0.004 16
Atmosphere
0.0274
0.0255
0.0253
atmosphere. These are very short residence times. Moreover, as the oceans occupy about
71% of the Earth surface, the active fresh water in the hydrologic cycle is continually
being distilled anew through ocean evaporation.
Maps depicting the approximate distribution of components of the water balance in
different parts of the world have been presented by Lvovitch (1973), Budyko (1974),
Baumgartner and Reichel (1975), Korzoun
et al.
(1977), and Choudhury
et al
. (1998). The
relative and absolute magnitudes of the main components of the hydrologic cycle, namely
P
R
and
E
, can vary over a wide range from one location to another. Obviously, the
long-term mean values of all three are negligible in desert locations. At the other extreme,
maximal annual precipitation values of up to 26.5 m have been recorded in a mountainous
monsoon environment (Cherrapunji, Meghalaya). Maximal mean evaporation values of
,
