Confronting coastal poverty: Building sustainable coastal livelihoods in South Africa

This is the second of two articles exploring coastal management in South Africa. It focuses on the adoption of the Sustainable Livelihoods approach that has underpinned recent policy implementation efforts. This approach complements prevailing coastal management thinking and practice by focusing attention on the strategies that poor people use to access coastal resources, mediated by governance institutions and social relations, in the pursuit of desired livelihood outcomes. South Africa's efforts to adopt this approach help to better understand coastal livelihood opportunities and challenges, identify priority interventions for improving livelihood prospects, and reveal imperatives for building sustainable coastal livelihoods.     

Integrated coastal fisheries management

There are two principal threats to sustainable coastal fisheries. The concern which has been evident in most parts of the world for many years is the existence of open access to fisheries which has led to over-capitalization, over-fishing of the resource and, often, conflict. Increasingly in recent years, however, a second threat has become apparent. This is the loss of fish habitat and deterioration of water quality brought about by environmental changes generated in other sectors. Integrated coastal fisheries management addresses these issues through a strategy in which the removal of open access plays the key role, supported by elements such as creation of awareness, local participation in management, training and research, and improved sectoral coordination and planning. It is noted that, very often, the amelioration of the second of the two principal threats may be dependent on the fishery sector resolving the first.     

The coastal undercurrent— A role of longshore scales in coastal upwelling dynamics

A simple three-dimensional model of a time-dependent coastal upwelling is discussed for time scales of several days to a week, with the linear, two-layer, flat-bottom and $\text{?-}\text{plane}$ approximation. Emphasis is placed on the effects of longshore scales determined by the longshore variabilities in the wind stress distributions. The responses of the inshore motions are shown to depend critically on the longshore scales. For a certain wide range of the scales, the system reveals dominantly baroclinic responses and a full development of the poleward coastal undercurrent without β effect. Somewhat detailed discussions are given on the coastal upwelling, the coastal jet and the poleward undercurrent, which are interpreted simply as the orbital velocities of the forced Kelvin-type waves.     

Development and management of a coastal litter campaign: The voluntary coastal partnership approach

The Forth Estuary Forum's Coastal Litter Campaign aimed to develop and implement a community involvement and public awareness-raising programme intended to tackle and monitor the issue of marine litter in the Firth of Forth, Scotland. Beach cleans are an excellent public participation exercise, focusing the public's attention on the issue of marine litter and creating a sense of environmental responsibility. Raising public awareness is the only guaranteed way of reducing marine litter. A combination of education, provision of adequate waste reception facilities and enforcement of legislation is needed to tackle beach litter.     

Constructing logbook-like statistics for coastal fisheries using coastal surveillance radar and fish market data

As catch and effort statistics including fishing time and location are essential for producing abundance indices for utilized fish stocks, fishing states are encouraged under the FAO Code of Conduct for Responsible Fisheries to collect and maintain such statistics. However, for coastal fisheries (including artisanal fisheries) that are mainly composed of small-sized vessels which are usually too numerous to monitor, fisheries statistics collection systems are often either lacking or of insufficient quality (e.g. incomplete or inaccurate). Vessel monitoring system (VMS) data are commonly used to construct or improve estimation of fishing effort and fishing location in large-scale fisheries. Most coastal fisheries lack VMS but their countries do have coastal surveillance radar systems (CSRS) for security and enforcement purposes. This study illustrates and recommends opportunistic use of CSRS data to provide similar scientific benefits to VMS data for coastal fisheries. CSRS in combination with market landings data can construct logbook-like catch and effort statistics. This study introduces a method and demonstrates its usefulness for scientific research and management purposes, including the potential to obtain a higher accuracy and precision, particularly for fishing location and catch amount. Limitations of the CSRS data and challenges to managers involved in its application are also discussed.     

Town meeting on America's coastal future: using the Internet to promote coastal stewardship

Ten national organizations developed a comprehensive vision for America's coastal future and then conducted a national dialogue about coastal futures over the Internet. Using the Internet town meeting, more than 7000 participants shared their views and perspectives about alternative coastal futures over a six-month period.This paper describes the development and implementation of the Internet town meeting and draws lessons for using the Internet to communicate at the grassroots level. It reports the results of the Internet town meeting and considers their implications for National Ocean and coastal management efforts.     

The role of coastal setbacks in the context of coastal erosion and climate change

Coastal erosion and storms represent a source of risk for settlements and infrastructure along the coast. At the same time, coastal natural assets, including landscape, are threatened by increasing development mainly driven by tourism. The Mediterranean coast is especially vulnerable to these processes, considering its high biological and cultural diversity. An additional challenge is represented by climate change, as it will force coastal communities to apply more or less drastic adaptation strategies. Coastal setbacks, used to protect coastal communities and infrastructure from storms and erosion, and to preserve coastal habitats and landscapes from degradation, is one of the main instruments suggested by the Protocol on Integrated Coastal Zone Management of the Barcelona Convention, entered into force on the 24 of March 2011. Its implementation has the potential to influence coastal policies in other regions, such as the neighbouring Black Sea.The CONSCIENCE project has formalized concepts and conducted specific studies to provide new tools for coastal erosion management practice. The objective of this paper is to present a synthesis of the research conducted into coastal setbacks for coastal erosion management and climate change adaptation. This is done by analysing the requirement of the Protocol, current processes and management practices in two case study areas (Costa Brava Bays in Spain and Danube Delta, in Romania) and the new challenges posed by climate change.     

A numerical study for the coastal upwelling and the coastal front off Zhejiang coast

A two-dimensional numerical model is constructed to study the interaction between the coastal upwelling and the coastal front off Zhejiang coast in summer. In the f-plane model, the shelf topography, continuous stratification, and Richardson number-dependent eddy coefficients are considered. The results show that the coastal up-welling off Zhejiang in summer can be divided into two regions, the nearshore one (Region A) and the offshore one (Region B). In Region A, the alongshore wind stress has more important effect on the coastal upwelling while in Region B, the upwelling is mainly induced by the Taiwan Warm Current. The results also suggest that the formation of coastal front off Zhejiang in summer is closely related to the strength of the coastal upwelling in Region A.     

Biological indicators in the Caribbean coastal zone and their role in integrated coastal management

Caribbean coastal ecosystems are increasingly being threatened by natural and anthropogenic factors. The scale of these factors is at local, national, regional and global levels. Threats include the effects of fisheries and extraction, eutrophication, siltation, and pollution as well as global climate events such as El Niño and global climate change. Integrated coastal management (ICM) should clearly demonstrate the adverse effects of environmental impacts, thus justifying the need for mitigation and should evaluate the success of management efforts. ICM requires robust indicators that gauge the ‘health’ of the coast in relation to environmental, social and economic activities. Biological indicators (bioindicators) offer a signal of the biological condition in an ecosystem. Using bioindicators as an early warning of pollution or degradation in an ecosystem can help sustain critical resources. Biological indicators in the Caribbean are focused around particular ecosystems, especially coral reefs, seagrass beds and mangrove forests and include a range of biological parameters relating to particular species, groups of species and biological processes. The use of these indicators is critically reviewed and the presence or absence of a relevant framework for their use in Caribbean ICM programs is discussed.     

Studies on coastal physical oceanography

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Studies on coastal physical oceanography

     

Coanda effect in coastal flows

In the present paper some numerical simulations and experiments were carried out to study jet-wall interaction in shallow waters. Namely, modifications of the hydrodynamic field concerning the interaction of river run-off with a shallow coastal water body, due to the presence of marine structures, were investigated. Stratification effects due to salinity and temperature were neglected, and the interest was focused on barotropic features (Coanda effect). The numerical analysis was carried out by means of shallow water equations, numerically solved by finite difference, and the present method was validated by means of a typical simple-shaped test case. The experiments were carried out in a shallow water tank, flow visualizations were performed, and the velocity field was obtained by PIV. The main features of jet-wall interaction flow were investigated in simple-shaped geometries, and applications were shown for two practical cases: Pescara channel harbour (Adriatic Sea, Italy) and the proposed design of Latina harbour (Tyrrhenian Sea, Italy).     

Management of Mediterranean coastal dunes

This paper gives some theoretical concepts of dune management as well as practical examples of how actual measures should be carried out.Dune management is defined as all measures aimed at the preservation and restoration of the natural values of a coastal sand dune area. It is essential that beach and foreshore are seen as parts of a whole dune system. Management must take into account all processes within this system. It should aim at nature conservation and wise use of coastal resources and all forms of land use should be ecologically sustainable. Dune management should work as much as possible ‘with’ the natural processes and not ‘against’ them.Four types of Mediterranean dune systems (including Portugal and SW Spain) are distinguished:: mainland dunes, lagoon-bay barrier dunes, delta dunes and remnant dunes.Like in most parts of the world, Mediterranean dunes fulfill several functions at the same time. The following functions will be dealt with: nature management, coastal defence and erosion, dune stabilisation and afforestation, agriculture, tourism and urbanisation, recreation, golf, information and education. The concepts of management which are considered include: sustainable use, large and coherent units, compensation, management planning, environmental impact assessment and function analysis.Dune stabilisation is not always considered necessary. In case of stabilisation by planting, only indigenous species should be used, preferably pioneers and not trees. Planting of exotic species should be avoided.     

The generation of coastal undercurrents

Equilibrium conditions in anf-plane ocean evolve as follows after the sudden onset of winds parallel to a coast. At first the flow is two-dimensional-spatial variations are confined to a plane perpendicular to the coast-and the salient features in the forcing region are acceleration of a coastal jet in the surface layers in the wind direction, and offshore Ekman drift that causes coastal upwelling. Kelvin waves excited at the edge of the forced region establish equilibrium conditions by creating an alongshore pressure gradient that balances the wind so that the acceleration stops. The vertical structure corresponding to each vertical mode differs from that of the wind-driven coastal jet so that the arrival of the barotropic Kelvin wave starts to accelerate a coastal undercurrent in a direction opposite to that of the wind. Subsequent baroclinic Kelvin waves modify the vertical structure of the coastal current so that the undercurrent in the subsurface layer is accelerated. In an inviscid model there is a singularity in the surface layers at the coast ast→∞ because the Kelvin modes with small offshore and vertical scales travel slowly and take a very long time to make their contribution to the establishment of equilibrium conditions. A modest amount of friction eliminates this problem. Nonlinearities are important in the heat equation and affect sea surface temperatures significantly but their effect on the momentum balance is secondary.     

Sensitivity study of coastal plumes

INTRODUCTIONIn laboratory, Griffiths and Linden (1981 ) simulated the buoyancy-driven coastal currentsusing both a ring source and a point source in a rotating cylinder tank. The POint source was simifar to the river-forced plume in the coastal region. The coastal plume together with the gravitycoastal current moved along the coast, keeping the barrier on the right in the Northern Hemisphere. Stern et al. (1982) also conducted a similar experiment using a rectangular tank and carried ou…     

Hydrocarbons in Washington coastal sediments

The sources and distributions of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons are characterized in seventeen sediments from a highly river-influenced sedimentary environment off the southwestern coast of Washington. The major hydrocarbons are land-derived, introduced as preformed compounds and display long-term stability in sediment cores. A series of PAH of anthropogenic origin and two naturally derived compounds, retene and perylene, dominate the PAH composition in these sediments. Plantwax n-alkanes are the major aliphatic hydrocarbon constituents. Aliphatic hydrocarbons of marine origin, pristane and a series of four acyclic, multibranched C₂₅ polyolefins, are also observed in many sediments. The concentrations of these marine-derived hydrocarbons decrease to negligible levels rapidly with sediment depth from the sea-sediment interface, suggesting degradation.In general, the major land-derived hydrocarbons are concentrated in the midshelf silt deposit which extends northwestward along the continental shelf from the Columbia River mouth. A quantitatively more minor, natural series of phenanthrene homologs, also of terrestrial origin, is preferentially advected further offshore and deposited in continental slope sediments. These distributions are consistent with recognized particle associations for these compounds and sediment dispersal processes in this coastal environment. Sediment core records suggest the present pattern of dispersal has persisted for at least the past century and possibly since the Late Pleistocene.     

Importance of tropical coastal environments

On a global basis, a very large fraction (>50%) of the mass flux from land to the marine environment enters from tropical rivers. A broad range of processes active in the adjacent coastal ocean determines the fate of this material. The tropical setting causes many of the coastal processes to be fundamentally distinct from those operating in temperate and polar regions. Therefore, their operation cannot necessarily be understood by extrapolation from empirical observations at higher latitudes. Other coastal processes are influenced by the extremely large water, particulate, and solute discharges from tropical rivers. Further complexity is added by the diverse range of geographic settings through which tropical rivers flow and into which they empty. In summary, coastal—ocean processes in the wet tropics are: globally important, fundamentally different than at higher latitudes, and diverse in operation. Many recent advances have been made in the understanding of the tropical coastal ocean, and it is hoped these will continue into the future. Such understanding is important for predicting processes of river—ocean interaction and terrestrial fluxes to the global ocean, which affect and are affected by human populations. It also can be combined with knowledge of temperate and polar settings to provide a comprehensive understanding of the coastal ocean.     

Double-celled circulation in coastal upwelling

Simple numerical experiments on two-dimensional coastal upwelling are made with emphasis on the role of non-geostrophic solenoidal field of density in the formation of double-celled circulation and multi-celled density front. Geometry of shelf and slope is not taken into account. Existence of poleward undercurrent presumably caused by the longshore variation of the large scale pressure field is also suppressed for the sake of simplicity.The results are, (1) double-celled circulation revealed in the present experiment is closely related with the internal frictional layer, where the horizontal density gradient balances with the vertical gradient of the longshore velocity and the vertical diffusion of the vorticity. (2) density front formed by the emergence of the pycnocline to the sea surface is successively advected offshoreward by the Ekman transport. (3) the pycnocline intersecting the sea surface forms the density front which is nearly vertical on account of the small scale convection. The surface currents converge at the front and construct an anti-clockwise circulation (viewed from the lee side). (4) small coefficient of eddy viscosity and strong wind stress lead the Ekman transport unstable and form a multi-celled structure in the frontal region.     

Manganese recycling in coastal waters

Both water and suspended particulate matter in the deep water of the Gulf of St. Lawrence are greatly enriched in manganese. Maximum dissolved manganese concentrations are encountered close to the sediment-water interface whereas the particulate matter with highest manganese content occurs 30–100 m above the bottom. The elevated concentrations are attributed to the diagenetic release of dissolved manganese from the underlying fine-grained sediments and its subsequent precipitation in the water column. The rate of manganese precipitation is rapid compared to the rates of diffusion and mixing in the bottom water. Part of the manganese-enriched particulate matter becomes mixed throughout the water column by advection and diffusion. Thus, particles enriched in manganese can ultimately be carried into the open ocean by prevailing currents. This process, which appears to be widespread in eastern Canadian coastal waters, enables manganese originally associated with rapidly settling terrigenous particles to be transferred to slowly settling fine-grained suspended particles entering the ocean from coastal environments. In this way, riverborne manganese of terrigenous origin may well account for a major proportion of the excess manganese in pelagic sediments.     

Developments in coastal engineering research

This paper presents a review of recent advances in understanding and modelling of hydrodynamic and morphodynamic processes in the coastal zone as well as some challenges for further developments. Different processes are distinguished, and for each of these, essential characteristics of the state-of-the-art are mentioned, with emphasis on recent developments, as well as open questions that are considered important.     

Numerical test of coastal frontogenesis

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