72
Tire Last Resource
parties interested in promoting new sources of water supply. There
is no doubt that industrial and political publicity has thrown up
smoke—screens which have confused both the public and the
popular press. On the other hand, the very distribution of water over
the surface of the Earth suggests that desalination has a distinctive
role to play in raising the hopes, health and prosperity of many
different peoples.
The oceans hold in the region of 97 per
cent of the Earth’s total
supply of water. Of the remainder, over 2 per
cent is locked away in
ice and snow, less than I per
cent is found in rivers, lakes and
ground—water, whilst the atmosphere holds about 1/1,oooth per cent.
However, these gures give little clue to the great ‘hydrologic
cycle’ responsible for the movement of water about the Earth. The
seas and land masses are continually giving up water vapour as a
result of solar heating. This vapour rises high in the atmosphere and
is carried by surface winds until it descends once again as rain, hail,
sleet or snow. Some of the precipitation falls on the land and makes
its way either directly or indirectly to the sea: it seeps into the
surface to join with the ground—water, or drains into rivets and
streams.
To obtain his water supply, man can interrupt this cycle at any
stage. So far this interruption has consisted largely of building dams
and reservoirs to hold the surface waters, but much still remains to
be done by way of tapping available water supplies; even in the
United States only 7-3 per
cent of the annual precipitation is
estimated to be used. The building of dams holds considerable
promise in many places which, though starved of water and power,
have large rivers owing through them; but where land is at a
premium it could well be that the cost of building the necessary
dams and buying the land to be drowned rules out this solution, and
water—supply companies may eventually nd it easier and cheaper
to look at the major reservoir of water, the oceans. ln such times,
the know—how and plant for desalination will literally control the
destinies of nations, irrespective of their past prosperity and impor—
tance.
Small wonder then that the traditionally ‘Well—watered’
countries are seriously investigating the various methods of ‘sweeten—
ing’ the seas. Small wonder too that a political shadow hangs over
current investment in desalination and water—supply engineering in
general.
Tire Last Resource
parties interested in promoting new sources of water supply. There
is no doubt that industrial and political publicity has thrown up
smoke—screens which have confused both the public and the
popular press. On the other hand, the very distribution of water over
the surface of the Earth suggests that desalination has a distinctive
role to play in raising the hopes, health and prosperity of many
different peoples.
The oceans hold in the region of 97 per
cent of the Earth’s total
supply of water. Of the remainder, over 2 per
cent is locked away in
ice and snow, less than I per
cent is found in rivers, lakes and
ground—water, whilst the atmosphere holds about 1/1,oooth per cent.
However, these gures give little clue to the great ‘hydrologic
cycle’ responsible for the movement of water about the Earth. The
seas and land masses are continually giving up water vapour as a
result of solar heating. This vapour rises high in the atmosphere and
is carried by surface winds until it descends once again as rain, hail,
sleet or snow. Some of the precipitation falls on the land and makes
its way either directly or indirectly to the sea: it seeps into the
surface to join with the ground—water, or drains into rivets and
streams.
To obtain his water supply, man can interrupt this cycle at any
stage. So far this interruption has consisted largely of building dams
and reservoirs to hold the surface waters, but much still remains to
be done by way of tapping available water supplies; even in the
United States only 7-3 per
cent of the annual precipitation is
estimated to be used. The building of dams holds considerable
promise in many places which, though starved of water and power,
have large rivers owing through them; but where land is at a
premium it could well be that the cost of building the necessary
dams and buying the land to be drowned rules out this solution, and
water—supply companies may eventually nd it easier and cheaper
to look at the major reservoir of water, the oceans. ln such times,
the know—how and plant for desalination will literally control the
destinies of nations, irrespective of their past prosperity and impor—
tance.
Small wonder then that the traditionally ‘Well—watered’
countries are seriously investigating the various methods of ‘sweeten—
ing’ the seas. Small wonder too that a political shadow hangs over
current investment in desalination and water—supply engineering in
general.