Definition and History of Hydrogeology - Hydrogeology: Objectives, Methods, Applications - page 3

C HAPTER A1
Definition and History of
Hydrogeology
1 THE SCIENCE OF GROUNDWATER
1.1 Etymology and defi nition
Hydrogeology (from the Greek hydra : water, ge : earth, and logos : discourse)
can be defi ned as the science of groundwater. That said, water forms a single
unit: precipitation, surface water, ice, and subterranean water are all parts
of a continuous cycle. Hydrogeology therefore cannot be separated from
surface hydrology, climatology, geology, and geography. Furthermore, as
with all modern sciences, it calls on the countless domains included in
physics, chemistry, and biology. As water becomes more and more valuable,
hydrogeologists are also confronted with social and political problems.
More, perhaps, than any other science, hydrogeology today requires an
interdisciplinary approach. Defi ning it precisely is therefore a diffi cult
exercise. Where does the subterranean world of the hydrogeologist begin
and end? Is water contained in magma a part of it? Do hot springs at mid-
ocean ridges fall under the domain of hydrogeology? Does one classify as
subterranean a river crossing a cave/tunnel such as the Mas d'Azil (Ariège)?
Is soil, where important physico-chemical reactions take place and where
water can be extracted by plants, a subterranean domain? The reader will
therefore understand that the simple defi nition “science of subterranean
water” is intentionally vague, so to be all the more precise.
1.2 History
The human body cannot function without water for more than two days. The
search for water was thus by necessity the fi rst step humans took in studying
their environment. Searching for a certain degree of quality is already seen