Geoscience Reference
In-Depth Information
hydrological research. At an undergraduate level,
however, the difference manifests itself through
earth science hydrology being more descriptive and
engineering hydrology being more numerate.
The approach taken in this topic is more towards
the earth science side, a reflection of the author's
training and interests, but it is inevitable that
there is considerable crossover. There are parts of the
book that describe numerical techniques of funda-
mental importance to any practising hydrologist
from whatever background, and it is hoped that the
topic can be used by all undergraduate students of
hydrology.
Throughout the topic there are highlighted case
studies to illustrate different points made in the
text. The case studies are drawn from research
projects or different hydrological events around the
world and are aimed at reinforcing the text else-
where in the same chapter. Where appropriate, there
are highlighted worked examples illustrating the
use of a particular technique on a real data set.
The
chemical properties
of water are equally impor-
tant for our everyday existence. Water is one of the
best solvents naturally occurring on the planet. This
makes water vital for cleanliness: we use it for
washing but also for the disposal of pollutants. The
solvent properties of water allow the uptake of vital
nutrients from the soil and into plants; this then
allows the transfer of the nutrients within a plant's
structure. The ability of water to dissolve gases such
as oxygen allows life to be sustained within bodies
of water such as rivers, lakes and oceans.
The capability of water to support life goes
beyond bodies of water; the human body is com-
posed of around 60 per cent water. The majority of
this water is within cells, but there is a significant
proportion (around 34 per cent) that moves around
the body carrying dissolved chemicals which are
vital for sustaining our lives (Ross and Wilson,
1981). Our bodies can store up energy reserves that
allow us to survive without food for weeks but not
more than days without water.
There are many other ways that water affects
our very being. In places such as Norway, parts of
the USA and New Zealand energy generation for
domestic and industrial consumption is through
hydro-electric schemes, harnessing the combination
of water and gravity in a (by and large) sustainable
manner. Water plays a large part in the spiritual
lives of millions of people. In Christianity baptism
with water is a powerful symbol of cleansing and
God offers 'streams of living water' to those who
believe (John 7:38). In Islam there is washing with
water before entering a mosque for prayer. In
Hinduism bathing in the sacred Ganges provides
a religious cleansing. Many other religions give
water an important role in sacred texts and rituals.
Water is important because it underpins our very
existence: it is part of our physical, material and
spiritual lives. The study of water would therefore
also seem to underpin our very existence. Before
expanding further on the study of hydrology it is
first necessary to step back and take a closer look at
the properties of water briefly outlined above. Even
though water is the most common substance found
on the earth's surface it is also one of the strangest.
IMPORTANCE OF WATER
Water is the most common substance on the surface
of the earth, with the oceans covering over 70 per
cent of the planet. Water is one of the few substances
that can be found in all three states (i.e. gas, liquid
and solid) within the earth's climatic range. The
very presence of water in all three forms makes it
possible for the earth to have a climate that is habit-
able for life forms: water acts as a
climate ameliorator
through the energy absorbed and released during
transformation between the different phases. In
addition to lessening climatic extremes the trans-
formation of water between gas, liquid and solid
phases is vital for the transfer of energy around the
globe: moving energy from the equatorial regions
towards the poles. The low viscosity of water makes
it an extremely efficient transport agent, whether
through international shipping or river and canal
navigation. These characteristics can be described
as the
physical properties
of water and they are critical
for human survival on planet earth.
