Geoscience Reference
In-Depth Information
Plate 25.8
Soil wash, gullying, bank collapse and stream incision are the main geomorphological processes at work in these
badlands in south-east Spain. The tracks to the right are goat and sheep walks. In the foreground left is seen the protection given
to the soil surface by vegetation (esparto grass, Stipa tenacissima) and an armour of stones.
Photo: Jonathan Carrivick
increased use of irrigation for high-value vegetables and
orchard crops. These trends have been most striking in
California and the Mediterranean region itself, but they
are evident to only slightly less a degree in the three
Mediterranean areas of the southern hemisphere.
These activities are viable only if sufficient water is
available to meet increasing domestic, industrial and
agricultural demands. These demands vary enormously
between the different activities, from the low demands for
potable water for drinking, through the medium demands
of industry, to the very high demands of agricultural
irrigation.
Table 25.2
shows the water requirements for
different purposes; as a rough rule of thumb, it is said that
an inhabitant of a Mediterranean area consumes ten times
as much water through products and services as in food
and drink.
Source of demand
Tonnes of
water needed
per tonne of
produce/tissue
Domesticated animals/humans
1
Industrial
Paper manufacture
250
Nitrogen manufacture
600
Agricultural
Sugar cane
1,000
Wheat
1,500
Rice
4,000
Cotton
10,000
