Geoscience Reference
In-Depth Information
sensitive areas. Many of these impacts involve stabilizing
beaches in order to maintain attractive tourist destinations for
economic purposes. Others are potential future outcomes re-
lated to global climate change and the effects rising sea level
will have on people living near the shore. Still other human in-
teractions are based on the desire to keep coastlines as environ-
mentally healthy as possible.
In this latter context, the nation was focused in July 2010
on the catastrophic oil leak from a ruptured well in the Gulf of
Mexico. Estimates indicated that over 757,000 L (200,000 gal)
of oil were streaming into the Gulf every day, causing grave
concerns about the impact on beaches and marine life in the
region. Geographers were involved in mapping the extent of
the spill and the coastal zones that were potentially harmed.
This section will discuss some of the ways humans impact
coastlines.
which to live and work, with spectacular views and numerous
recreational opportunities. However, coastlines are one of the
more sensitive landscapes on Earth, with changes occurring on
a daily basis and major adjustments taking place when strong
storms such as hurricanes strike.
Although extreme events such as hurricanes are indeed
dangerous, they are statistically rare along any particular stretch
of coast. As a result, people tend to be much more concerned
about the erosion associated with less severe storms, waves, and
high-water level. Unchecked, the effects of shoreline erosion
on coastal communities can be disastrous (Figure 19.36). In an
effort to control these effects, people have devised a variety of
protective structures.
Perhaps the most common way people attempt to mitigate
coastal erosion is to build
sea walls
and
revetments
that armor
the shore. As the name implies, a sea wall is a vertical, wall-like
structure built along the coast, usually at the landward edge of
a beach, where a bluff or dune may occur. Figure 19.37 shows
a sea wall at Palm Beach, Florida. Many protective structures
are less elaborate, consisting of large rocks and sometimes even
cement blocks from old roads. This kind of protection is called
rip-rap
and forms a revetment because it is usually applied to
a preexisting slope, rather than being built vertically. Although
sea walls and revetments protect the property they front from
erosion, they cause more extensive erosion up and down shore
than would otherwise occur naturally because the erosive power
of waves is transferred to and concentrated on those locations
(Figure 19.38).
Coastal Engineering
One of the most obvious ways that people impact the coast-
line is through engineered structures. Although these structures
come in a wide variety of forms, they are generally built with
the idea of (1) protecting the shore and shorefront homes from
coastal hazards such as erosion and storm surges, (2) stabilizing
and nourishing beaches, or (3) maintaining or improving the
flow of trade or traffic into ports.
Shoreline Protection
Of the many people who live near
U.S. coastlines, a large number choose to reside or work di-
rectly on the shore (Figure 19.35). The reasons for this choice
are probably obvious, as the shore is a pleasurable landscape in
Figure 19.35 Coastal development on Padre Island, Texas.
Much of this barrier island, which is shown in the satellite image
in Figure 19.26, is heavily developed. This pattern of development
is very common along the Gulf and Atlantic coasts of the United
States.
Figure 19.36 Effects of coastal erosion on personal property.
Severe bluff erosion along this stretch of the California coastline
can be a problem for those who choose to live really close to
shore.
