184
R.H. Charlier and Chr. P. De Meyer
If, on Bali, wave attack and natural causes are the culprits of the shrinking of the
beaches of Uluwatu and Tanah Lot, and shore-line retreat at Siyut and Lebih can
be ascribed to river mouth shifting, losses of beach width on Southern Bali are
due to man's activities • tourism having made spectacular advances on this island,
lengthening of the runway at Ngurah Rai airport appeared advisable, but 800
additional meters of runway jutting out at sea led to serious damage at Kuta
Beach. Traditional coral extraction, and ensuing gradual destruction of the reef,
have brought about beach regression at Batumadeg, Sanur, Nusa Dua, and
intensified the phenomenon at already damaged Kuta Beach. Both coral and sand
are used for ornamental and/or building material in local construction : removal
of river material is the principal cause of erosion on Gumbrich Beach. The
touristic demand for hotel rooms "on the beach" has led to the siting of such
facilities and the constructions interfere with natural maintenance processes.
Remedial action is urgently needed.
Extraction of coral poses equally severe, and solution-demanding problems, on
the Maldive Islands.
A typical example of coastal erosion problem in developing countries is provided
by B6nin. Geophysical factors, but far more the construction of the Akossombo
(Ghana) barrage and of the harbors of Lom6 (Togo) and Cotonou (B6nin), are
responsible for the spectacular retreat of beaches on the Gulf of B6nin. Here
erosion has been monitored since 1908 although observations of shoreline retreat
were made since 1901 : the coastline migrated inland by at least 20 m (66 r)
between 1892 and 1900. A dramatic acceleration of beach loss has occurred since
1960, when the Ghana barrage was constructed on the one hand, and, on the
other important harbor improvements were undertaken at both Lom6 and
Cotonou. One of the authors observed, in 1972 the extensive damage resulting
from sand removal for construction, hotel construction and urbanisation projects.
The barrage is a sediment trap and longshore currents now remove littoral sand
and erode near-shore ocean floor. At Lom6 the harbor jetty impedes sand
transport, sediments accumulate on its west flank and there is no beach
nourishment east of it.
Only fronting the Tropicana Hotel (Lom6), has erosion abated, apparently due to
the outcropping of calcareous cemented sandstone (beach rock) which, once
denudated, acts as a natural breakwater.
At Cotonou, near Grand Popo where the beach gained some 7 m (22.5 ft) upon
the sea at the turn of the century, erosion is acute because of jetties and the
Kp6m6 wharf. Renewed accretion, however, has been noticed near $6m6 where
quarrying of sand has been stopped.
R.H. Charlier and Chr. P. De Meyer
If, on Bali, wave attack and natural causes are the culprits of the shrinking of the
beaches of Uluwatu and Tanah Lot, and shore-line retreat at Siyut and Lebih can
be ascribed to river mouth shifting, losses of beach width on Southern Bali are
due to man's activities • tourism having made spectacular advances on this island,
lengthening of the runway at Ngurah Rai airport appeared advisable, but 800
additional meters of runway jutting out at sea led to serious damage at Kuta
Beach. Traditional coral extraction, and ensuing gradual destruction of the reef,
have brought about beach regression at Batumadeg, Sanur, Nusa Dua, and
intensified the phenomenon at already damaged Kuta Beach. Both coral and sand
are used for ornamental and/or building material in local construction : removal
of river material is the principal cause of erosion on Gumbrich Beach. The
touristic demand for hotel rooms "on the beach" has led to the siting of such
facilities and the constructions interfere with natural maintenance processes.
Remedial action is urgently needed.
Extraction of coral poses equally severe, and solution-demanding problems, on
the Maldive Islands.
A typical example of coastal erosion problem in developing countries is provided
by B6nin. Geophysical factors, but far more the construction of the Akossombo
(Ghana) barrage and of the harbors of Lom6 (Togo) and Cotonou (B6nin), are
responsible for the spectacular retreat of beaches on the Gulf of B6nin. Here
erosion has been monitored since 1908 although observations of shoreline retreat
were made since 1901 : the coastline migrated inland by at least 20 m (66 r)
between 1892 and 1900. A dramatic acceleration of beach loss has occurred since
1960, when the Ghana barrage was constructed on the one hand, and, on the
other important harbor improvements were undertaken at both Lom6 and
Cotonou. One of the authors observed, in 1972 the extensive damage resulting
from sand removal for construction, hotel construction and urbanisation projects.
The barrage is a sediment trap and longshore currents now remove littoral sand
and erode near-shore ocean floor. At Lom6 the harbor jetty impedes sand
transport, sediments accumulate on its west flank and there is no beach
nourishment east of it.
Only fronting the Tropicana Hotel (Lom6), has erosion abated, apparently due to
the outcropping of calcareous cemented sandstone (beach rock) which, once
denudated, acts as a natural breakwater.
At Cotonou, near Grand Popo where the beach gained some 7 m (22.5 ft) upon
the sea at the turn of the century, erosion is acute because of jetties and the
Kp6m6 wharf. Renewed accretion, however, has been noticed near $6m6 where
quarrying of sand has been stopped.