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14 Tides and Waves on Vegetated Coasts
Tidal flats are environments of net accumulation within coastal lagoons. They
play an important role in lagoon dynamics, heat exchange, and nutrient inputs.
In tidal flats, the inhabitants, mostly different species of worms and shells, must
be able to withstand strong environmental stresses, such as large variations of
salinity and temperature, storms, sediment load, shifting sands and anaerobic
conditions.
Coral reefs are a common and important feature in tropics, especially in
the Pacific region. Although ultimately morphologic and biological variability of reefs involves complicated interactions between chemical, biological and
physical parameters, wave energy has long been recognized as one of the most
important controls of coral growth and subsequent reef development. Coral
reefs are also vital for the protection of coastlines against the attack of cyclone
waves.
Accumulations of gel-like fluid mud front many coastlines, from the humid
tropics of the equatorial latitudes to temperate latitudes. Most coastal fluid
muds occur as intertidal and subtidal mudshoals near major rivers. In addition to serving as temporary and transitory storehouses for littoral sediments,
intertidal mudflats can be colonized by vegetation, such as seagrasses.
Hydrodynamics of vegetated coastal zones, and especially the processes associated with wave motion, are still very poorly understood. Various types of
ecological models are used to simulate the impact of specific developments on
vegetated environments to provide the physical and biological consequences of
alternative solutions for coastal regions. Most existing ecological models concentrate on the flow pattern, transport and dispersion of the pollutants or other
substances. However, in these models the surface wave impact is usually neglected. Any predictive models for sediment transport, coastline stability, coral
growth and its physical degradation need a substantial knowledge of tidal and
surface wave mechanics. In this chapter, we discuss some theoretical and experimental results of various aspects of tidal and wave motion and their impact
on the ecology of vegetated coasts.
14.2 Tides and Waves in Mangrove Forests
14.2.1 Tide-Induced Water Motion in Mangrove Forests
Mangroves are densely vegetated mudflats that exist at the boundary of marine and terrestrial environments (Fig. 14.1, see colour plate p.566). Inherent in these habitats is their ability to survive in a highly saline environment
(Robertson and Alongi, 1992; Alongi, 1998). In recent years it has been realized
that mangroves may have a special role in supporting fisheries, stabilizing the
coastal zone and protecting the lives and properties of the people living near
the sea and offshore islands (Jackson and Winant, 1983; Jenkins and Skelly,
1987; Qureshi, 1990; Siddiqi and Khan, 1990; Mazda et al., 1997a).
Hydrodynamic factors playa major role in the structure and function of mangrove ecosystems. Biogeochemical and trophodynamic processes, and forest
14 Tides and Waves on Vegetated Coasts
Tidal flats are environments of net accumulation within coastal lagoons. They
play an important role in lagoon dynamics, heat exchange, and nutrient inputs.
In tidal flats, the inhabitants, mostly different species of worms and shells, must
be able to withstand strong environmental stresses, such as large variations of
salinity and temperature, storms, sediment load, shifting sands and anaerobic
conditions.
Coral reefs are a common and important feature in tropics, especially in
the Pacific region. Although ultimately morphologic and biological variability of reefs involves complicated interactions between chemical, biological and
physical parameters, wave energy has long been recognized as one of the most
important controls of coral growth and subsequent reef development. Coral
reefs are also vital for the protection of coastlines against the attack of cyclone
waves.
Accumulations of gel-like fluid mud front many coastlines, from the humid
tropics of the equatorial latitudes to temperate latitudes. Most coastal fluid
muds occur as intertidal and subtidal mudshoals near major rivers. In addition to serving as temporary and transitory storehouses for littoral sediments,
intertidal mudflats can be colonized by vegetation, such as seagrasses.
Hydrodynamics of vegetated coastal zones, and especially the processes associated with wave motion, are still very poorly understood. Various types of
ecological models are used to simulate the impact of specific developments on
vegetated environments to provide the physical and biological consequences of
alternative solutions for coastal regions. Most existing ecological models concentrate on the flow pattern, transport and dispersion of the pollutants or other
substances. However, in these models the surface wave impact is usually neglected. Any predictive models for sediment transport, coastline stability, coral
growth and its physical degradation need a substantial knowledge of tidal and
surface wave mechanics. In this chapter, we discuss some theoretical and experimental results of various aspects of tidal and wave motion and their impact
on the ecology of vegetated coasts.
14.2 Tides and Waves in Mangrove Forests
14.2.1 Tide-Induced Water Motion in Mangrove Forests
Mangroves are densely vegetated mudflats that exist at the boundary of marine and terrestrial environments (Fig. 14.1, see colour plate p.566). Inherent in these habitats is their ability to survive in a highly saline environment
(Robertson and Alongi, 1992; Alongi, 1998). In recent years it has been realized
that mangroves may have a special role in supporting fisheries, stabilizing the
coastal zone and protecting the lives and properties of the people living near
the sea and offshore islands (Jackson and Winant, 1983; Jenkins and Skelly,
1987; Qureshi, 1990; Siddiqi and Khan, 1990; Mazda et al., 1997a).
Hydrodynamic factors playa major role in the structure and function of mangrove ecosystems. Biogeochemical and trophodynamic processes, and forest