Geoscience Reference
In-Depth Information
water. In many places throughout the world, coastal water supplies have been ren-
dered unsuitable for domestic and agricultural purposes by such exploitation (e.g.,
Khan and Sapna
2004
; Ergil
2000
; Bear et al.
1999
). The Ghyben-Herzberg relation,
for example, suggests that under hydrostatic conditions, the weight of a unit column
of fresh water extending from the water table to the interface is balanced by a unit
column of saltwater extending from sea level to the same depth as the point on the
interface. This analysis assumes hydrostatic conditions in a homogeneous, uncon-
fined coastal aquifer. According to this relation, if the water table in an unconfined
coastal aquifer is lowered by 1 m, the saltwater interface will rise 40 m. Therefore,
rising sea levels, which may occur by global warming, will result in seawater
intrusion; this may damage many coastal aquifers that currently supply major
quantities of fresh water (e.g., Sherif and Singh
1999
).
3.3.3 Impacts on Infrastructure
Salinization also has consequences on infrastructure maintenance and durability
(e.g., Wilson
2001
). Some of the effects include:
• Damage to houses, buildings, and other structures caused by the deterioration of
brick, mortar, and concrete, resulting from saline water crystallizing in brick-
work (e.g., Cole and Ganther
1996
).
• Corrosion of metal buried in the ground or set in structural concrete (e.g., Cole
and Ganther
1996
).
• Shifting or sinking of foundations, which may result in structural cracking,
damage, or collapse. Damage to heritage buildings may be of particular concern,
and land values may be degraded.
• Salt damage to roads and highways including the breakdown of concrete,
bitumen, and asphalt with associated pot holing, cracking, and crumbling of the
road base.
• Damage to underground pipes, cables, and other infrastructure due to the
breakdown of unprotected metal, cement, and other materials.
• Poorer water quality for industrial and domestic washing purposes, resulting in
an increased need for water conditioners and detergents, as well as the deteri-
oration of vegetated parks and gardens.
3.3.4 Impacts on Biodiversity and the Environment
Salinization has profound effects on many ecological niches and may cause dis-
tortion of biodiversity in many delicate zones. Fluctuating water table levels and
increasing salinity have serious impacts on native vegetation, in the same way they
do for crops and pastures (e.g., Cramer and Hobbs
2002
). Remnant vegetation may
