Geography Reference
In-Depth Information
Figure 4.5
Changes in cyclone frequency for the Lesser Antilles and its island sub-groups, 1650-1995 (updated to
include the 1990s, after Walsh 1998).
it tends to be zoned, decreasing with increasing
distance from the path of the eye of the cyclone
(Box 4.1).
The principle of the protective (and
landbuilding) role of mangroves (Box 4.1) formed
a cornerstone of plans in the 1980s to help to
protect the coastline of the deltas of the Ganges
and Brahmaputra in Bangladesh (Stoddart and
Pethick 1984; Stoddart 1987), where a 10 m storm
surge in a cyclone in 1970 resulted in an estimated
280,000 deaths in the delta region, in part because
of the failure of a previous scheme, which had
involved the construction of massive polders
surrounded by 5 m high earth banks. These proved
too expensive and difficult to maintain, and many
were breached or overtopped by the storm surge,
drowning those who thought they were protected
by the scheme. Damage and loss of life were less in
the west of the delta, where the traditional
mangrove vegetation was more intact. The scheme
adopted in the 1980s has been to protect the
coastline by restoring the previous natural belt of
fringing mangroves, with 65,000 ha planted by
1987 (Stoddart 1987). As well as providing physical
protection against waves, wind and storm surge
erosion and promoting sedimentation, the
mangroves would provide timber and firewood,
generate by-products such as honey, prawns and
fish and eventually aid the transition of land (with
sedimentation) from timber to paddy. Despite
these measures, however, when the area was struck
by a cyclone in 1991, much of the region was
