and transport them, the diffuser diameter is reduced progressively as
shown in Fig. 15.14.
An outline of a preliminary outfall design is given in Worked
Worked example
15.8 Coastal management
A large percentage of the world population lives along the coasts. A coastal
zone is the interface between land and sea including beaches, coastal
marshes, mudflats, mangroves, estuaries, etc. The principal demands on
coastal zone development include property (buildings, highways, land),
leisure activities (tourism, recreation), commercial interests (shipping,
fishing), minerals and disposal of wastes (industrial and domestic wastes).
Coastal planners are interested in the use of coastal zones to maintain
and develop some of the existing facilities and to initiate new schemes adding
fresh demands on the coasts. Thoughtless planning can upset the very charac-
ter of the coasts forever and seriously reduce coastal resources. Engineers
design, construct and maintain breakwaters for harbours, structures for
coastal defence, etc. In many instances construction of harbours or preven-
tion of erosion along a particular reach of coastline has interrupted littoral
drift causing serious downdrift problems. Site-specific solution can transfer
the problem to adjoining sites. Hence traditional solutions of defending a
particular site along the shoreline against flooding or erosion are now being
challenged in the light of better understanding of the coastal processes.
Conservationists are concerned about the impact of growing
demands on the coastal environment and the loss or decline of natural
habitats, marine life etc., by coastal activities and/or pollution. The
environmental assessment of its impact on the various features of the
coast such as flora and fauna forms therefore an essential part of any
project.
The objective of coastal management is to preserve the coastal
resources at the same time balancing the sometimes conflicting require-
ments of development, protection, usage and protection (see Barrett,
1989). In a broader sense social, economic, cultural, national and inter-
national considerations play an important rôle in the development of
coastal management strategies (see Kay and Alder, 1999).
In the past administrators, planners and engineers who have the
responsibility for providing and monitoring coastal defences were usually
only interested in the length of coast falling within their administrative
boundary. But it is the physical features of the coast and the coastal
processes, particularly the sediment motion, that should define the bound-
aries for integrated shoreline management plans.
Shoreline management plans should have the following objectives
662 COASTAL ENGINEERING
