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Optimizing the location of wind and photovoltaic solar power plants is a significant environmental management problem. The effectiveness of the site selection process for renewable energy systems (RES) could be strengthened by flexible spatial and environmental planning strategies using decision support systems (DSS) to critically identify the most productive, environmentally friendly and acceptable sites for the production of sustainable and reliable wind and solar energy. This study discusses hybrid DSS, using multi-criteria evaluation based on the analytical hierarchy process (AHP), a geographical information system (GIS), fuzzy logic, and a weighted linear combination (WLC) approach to determine optimal locations for renewable energy generation infrastructure. In the first stage, the most decisive factors for evaluating the site suitability were identified, based on experts’ opinions. Next, raster layers of ecological and socioeconomic sub-criteria were prepared GIS software. After incorporating the raster maps of each parameter, fuzzy membership functions were applied to normalize each raster layer between 0 and 1. The relative weights of different indicators were calculated using super decision software. Prioritizing vital elements were performed using AHP. In the final stage, the WLC approach was utilized to amalgamate layers in the GIS environment, which afforded the final site suitability maps. In Isfahan Province, Iran, 26% of the land area was found to be highly suitable for solar farms with 18% being highly suitable for wind farms. The results illustrate that using and comparing the results from combinations of computer-based DSS are more likely to result in better decisions than using individual DSS tools for the determination of the most suitable sites for RES location.

Monitoring vessel traffic in coastal regions is a key element of maritime security. For this reason, additional ways of detecting moving vessels are explored by using the unique structure of their wake waves based on pressure measurements at the seabed. The experiments are performed at a distance of about 2 km from the sailing line using novel multisensor devices called “hydromasts” that track both pressure and near-bed water flow current velocities. The main tool for the analysis is a windowed Fourier transform that produces a spectrogram of the wake structure. It is shown that time series from the pressure sensors, measured at a frequency of 100 Hz, 0.2 m above the seabed are a valid source of input data for the spectrogram technique. This technique portrays the properties of both divergent and transverse waves with an accuracy and resolution that is sufficient for the evaluation of the speed and distance of the detected vessels from the measurement device. All the detected passings are matched with vessels using automatic identification system (AIS) data. The use of several time series from synchronized multisensor systems substantially suppresses noise and improves the quality of the outcome compared to one-point measurements. Additional information about variations in the water flow in wakes provides a simple and reasonably accurate tool for rapid detection of ship passages.

Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are stongly affected by human activities. A multitude of human impacts, including climate change, affects the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. We conclude that a sound management and regulation of human activities must be implemented in order to use and keep the environments and ecosystems of the Baltic Sea region sustainably in a good shape. This must balance the human needs, which exert tremendous pressures on the systems, as humans are the overwhelming driving force for almost all changes we see. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.

We analyse the impact of ship traffic in the vicinity of navigation channels in a wide shallow waterbody. The crucial hydrodynamic driver in this situation is the depression (Bernoulli) wake that may be transferred into a long-living solitary wave of depression over the shoals. The analysis considers navigation channels in the Venice Lagoon using a new large dataset of approximately 600 measured wake events associated to specific ships whose data are provided by the AIS system. Since the development of the modern industrial port and the opening of the Malamocco–Marghera channel in the late 1960s, growing pressure on the lagoon caused by ship traffic has raised concerns about its physical integrity and habitat survival. The transit of large vessels has been shown to have serious impacts on the shallow water areas adjacent to waterways. Depression wakes created by such vessels can reach significant dimensions (water level dropdown of up to 2.45 m at the channel margin), causing unusually large retreat rates of several sections of the shoreline and which may adversely affect the lagoon morphology. The wakes are analysed in relation to ship and morphological parameters. A formulation is proposed to predict wake amplitude on the basis of ship characteristics and motion.

There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. This, along with the outstanding number of long data records, makes the Baltic Sea a unique laboratory for advancing our knowledge on interactions between processes steering sea level and erosion in a climate change context. Processes contributing to sea level dynamics and coastal erosion in the Baltic Sea include the still ongoing viscoelastic response of the Earth to the last deglaciation, contributions from global and North Atlantic mean sea level changes, or contributions from wind waves affecting erosion and sediment transport along the subsiding southern Baltic Sea coast. Other examples are storm surges, seiches, or meteotsunamis which primarily contribute to sea level extremes. Such processes have undergone considerable variation and change in the past. For example, over approximately the past 50 years, the Baltic absolute (geocentric) mean sea level has risen at a rate slightly larger than the global average. In the northern parts of the Baltic Sea, due to vertical land movements, relative mean sea level has decreased. Sea level extremes are strongly linked to variability and changes in large-scale atmospheric circulation. The patterns and mechanisms contributing to erosion and accretion strongly depend on hydrodynamic conditions and their variability. For large parts of the sedimentary shores of the Baltic Sea, the wave climate and the angle at which the waves approach the nearshore region are the dominant factors, and coastline changes are highly sensitive to even small variations in these driving forces. Consequently, processes contributing to Baltic sea level dynamics and coastline change are expected to vary and to change in the future, leaving their imprint on future Baltic sea level and coastline change and variability. Because of the large number of contributing processes, their relevance for understanding global figures, and the outstanding data availability, global sea level research and research on coastline changes may greatly benefit from research undertaken in the Baltic Sea.

Despite repeated efforts to transplant mangroves to stop coastal erosion, the Brebes coasts were severely eroded between 2010 and 2013. Effective coastal erosion control in Brebes is not possible if the current situation is not adequately addressed and problems not properly identified. This study applied participatory action research methods for critically reviewing current mangrove transplantation projects in Brebes Regency, Indonesia. Mangrove transplantation has had limited success in restoring Brebes eroding coasts. Inefficient nursery operation, the wrong choice of mangrove species, improper transplantation techniques, poor coastal protection, and inadequate ongoing monitoring and evaluation significantly contributed to the limited success. Inadequate monitoring and evaluation meant that few lessons were learnt and the same mistakes continued to be made. Recommendations for production of mangrove seedlings, mangrove transplantation techniques, and monitoring and evaluation are provided to ensure effective mangrove transplantation in the future in Brebes Regency, Indonesia.

Coasts worldwide are facing enormous challenges relating to extreme water levels, inundation and coastal erosion. These challenges need to be addressed with consideration given to the need for infrastructure such as for ports and other socio-economic developments, especially for coastal tourism. Choosing the optimal decision support tools (DSTs) for coastal vulnerability and resilience assessment is a major challenge for decision-makers and coastal planners. The robustness and flexibility of coastal decision-making can be improved by using effective DSTs, particularly for the management of coastal hazards. This study provides an overview of the construction and use of decision support systems (DSSs) as combinations of DSTs, such as the commonly used multi-criteria decision analysis (MCDA) methods and an artificial neural network (ANN), integrated with a geographical information system (GIS). The experience of many researchers is that the combination of MCDA techniques based on fuzzy logic, analytical hierarchy process (AHP) and weighted linear combination (WLC), with GIS, and possibly also incorporating ANN, provides decision-makers with a comprehensive tool for efficiently calculating decision support indices (DSIs). Hybrid tools are becoming more popular and relevant among experts due to their multiple functionalities that facilitate decision-making. An integration of DSTs in a DSS and further development of DSIs provides a path for the integration of quantitative and qualitative parameters into the decision-making process, and providing materials to be used in consultation processes. An integrated DSS is more likely to produce high-quality results for decision-makers, handle the uncertainty of analysis, and extend the long-term applicability of tools employed by coastal managers.

Vessel detection and localization based on wake measurements have been used extensively in aerial and satellite reconnaissance. Here, a wake-based approach for vessel localization and speed estimation is developed using a grid of pressure sensors on the seabed. The sensor array consisted of 9 devices in a 3 × 3 rectangular grid with 2.5 m spacing between the instruments. The array was deployed at a depth of 3 m approximately 2.5 km from the fairway. The pressure time series from all sensors were used to estimate vessel speed and the travelling distance of the wake by interpreting the geometry of its time-frequency representation. The wake direction and an estimate of the vessel course are calculated from the delays of the incoming wake between the sensor locations, equivalently, based on cross-correlations of the signal at neighbouring sensors. Results for single events are compared with data collected from the vessels self-reporting systems (AIS). It is concluded that a grid of pressure sensors can provide a reliable estimation of the vessel location and its speed. The presented technique makes it possible to locate ships, and their speed and course, as the next step towards a vessel traffic monitoring system based on wake recordings.

By 2009, the Kien Giang coast, Vietnam, had experienced significant coastal erosion and mangrove degradation. Recent mitigation strategies, developed through policies, plans and mangrove planting programs have not been successful, in part because the causes of coastal erosion were not adequately identified. This paper investigates the relationship between human activities and coastal erosion in Kien Giang province. This study used mixed methods to understand the causes of coastal erosion with an emphasis on human activities. In this investigation, local communities were involved as co-investigators to explore the causes of coastal erosion in Kien Giang province. While natural factors (adverse effects of climate change and sea level rise) have been widely reported as main causes of coastal erosion, human activities initially were not recognised by local communities as significant contributors to coastal erosion and mangrove degradation. Human activities such as poor aquaculture pond construction, poor construction of new and upgraded sections of the sea dyke system, mangrove afforestation using only a single species, mangrove cutting for commercial and domestic uses, and construction of local boating channels, and the interaction of anthropogenic activities and physical processes are significant contributors to erosion. The study resulted in the awareness of the impact of community activities on the coast being improved. Knowledge gaps and necessary policy changes are identified.

While current coastal erosion solutions have had limited success in controlling coastal erosion, the gradual expansion of mangrove areas was effective in stabilizing an actively eroded mangrove dominated muddy coast in Vam Ray, Kien Giang, Vietnam for a short time period. The gradual expansion method was developed as a result of local comprehensive involvement and capacity, and the integration of different knowledge systems. However, the method was not sufficiently reported. Local involvement and capacity were not adequately emphasized during the reporting process. Insufficient reporting caused the failure in replicating the method elsewhere in Kien Giang. Inadequate emphasis of local involvement and capacity probably breached moral rights for the Vam Ray community. This manuscript documented the gradual expansion method using different sources of data and information and inputs from the key Vam Ray community members. The gradual expansion method involved closure of current mangrove gaps by transplanting mangroves protected by appropriate fences as the first stage, and gradual expansion of the mangrove belt seawards in the second stage. The method has a potential replication elsewhere in Vietnam and in Southeast Asia.

Local and scientific knowledge, when adequately and properly integrated, produces enormous benefits for natural resource management in comparison to a single knowledge system being used. Adequate a...

A management policy adopted by the Kien Giang Province, Vietnam, is to allocate mangroves areas using contracts with local community members who are dependent on mangrove resources for both mangrove protection and livelihood improvement. However, community members have not made the best use of the allocated areas, and mangroves have not been well protected. The policy is due to be revised in late 2016, as is legally required. This study used mixed methods to review the policy and its implementation with respect to mangrove protection requirements and use of mangroves for livelihood improvement and to provide recommendations for sustainable mangrove management in Kien Giang. The policy and its implementation is demonstrated to be a constraint to achieving its goal. Limited understanding of the policy of contractees resulted in ineffective and inefficient aquaculture and mangrove protection in almost all areas. Permitted thinning and selective harvests led to the creation of substantial gaps and disconnections in the established mangroves, making the entire coastline vulnerable to coastal erosion. Improper technical guidance on the configuration of mangrove allocations, and mangrove protection and transplantation methods resulted in the mangrove protected areas being fragmented and vulnerable to erosion. Permitted thinning and selective harvest practices should be reviewed to ensure adequate resilience and protection of mangrove areas, especially on critically eroding areas. Proper law enforcement should be put in place to ensure contracts are adequately implemented. Allocation and/or transferal of areas less than 1 ha must be discontinued in the future to avoid further defragmentation and degradation. Technical guidance on configuring allocated mangrove areas should be established and incorporated into the updated policy that would help improve the effectiveness of the policy, and address problems relating to strengthening resilience and protection of mangrove areas in Kien Giang Province, Vietnam. Similar programs using mangrove area allocation to individuals and households in response to mangrove area loss exist elsewhere in the Mekong delta. Understanding the reasons for the very limited success of the Kien Giang program and local co-investigation in drawing lessons learnt can help guide other similar programs elsewhere in the Mekong Delta region.

Mangrove dominated muddy coasts (MDMCs) throughout the world have been made vulnerable to erosion by human induced and natural factors. Meanwhile, their management has not been clearly identified in the literature. This study uses a comprehensive literature review to describe strategies, specifically designed to manage MDMCs for effectiveness, and provides recommendations for sustainable management of these coasts. Only a small percentage of previous studies deals with real-world management of MDMCs. Two approaches that are specifically designed to manage MDMCs are science-based approaches and local knowledge-based approaches. Both approaches, each having advantages, have had limited success in effectively managing MDMCs, with a low level of local involvement, and a minimal integration of the different knowledge systems. MDMCs and their management should be distinguished from other types of coasts to avoid possible confusion in the literature. Mechanisms are needed for integrating different knowledge systems for effectively managing MDMCs. These mechanisms should promote a high level of integration of local and scientific knowledge, local ownership, and sustainability.

It is common for environmental restoration projects to be reviewed by the administering organizations but it is much less common for the communities that the projects are meant to serve to detail their experiences and perceptions of the outcomes. We evaluate an internationally funded mangrove restoration project and reflect upon the lessons learned in regard to the project strategies and interventions, particularly from the perspective of the local community. The Vam Ray coast, Kien Giang Province, Vietnam, was seriously eroded by 2008. In May 2009, a demonstration project was established which achieved a high survival rate of transplanted mangroves and sea mud accumulation. This study used participatory action research methods (literature review, semi-structured interviews, field visits, and peer debriefing) to evaluate the project outcomes. Despite the project being generally very successful, its implementation and results were inadequately documented by agencies involved due in large part to insufficient local involvement during the reporting process, even though the local community was fully involved in the project planning and implementation. Inadequate documentation has led to mistakes being made when attempts have been made to replicate the project elsewhere, and incomplete findings have been incorporated into mangrove management plans at the provincial and regional levels. Using the community knowledge from the time of the project implementation and since, we detail the successes and problems encountered to provide more complete reporting, to assist transferability of the methods to other eroding muddy coasts in Vietnam and potentially elsewhere.

Ratsep, M.; Parnell, K.E., and Soomere, T., 2020. Detecting ship wakes for the study of coastal processes. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1258–1262. Coconut Creek (Florida), ISSN 0749-0208.Wakes from contemporary vessels may affect, and in some places dominate, coastal processes in the vicinity of major shipping lanes. The analysis of the properties and impact of wakes has generally been restricted to wakes that can be visually observed in raw data. In this work, spectral analysis of the time series of single-point measurements of water surface elevation from Tallinn Bay is used to highlight the structure of ship wakes using a Short Time Fourier Transform. This method makes it possible to determine the speed and distance of a vessel from the measurement site. Wakes are detected using an algorithm based on Gabor multipliers. The results are compared with vessel passages retrieved from the Automatic Identification System (AIS) data. The algorithm detects the majority of ship wakes that can be visually recognized in spectrograms and misses only those with low signal to noise ratio or those in close proximity to another vessel wake. The calculated speed and distance are consistent with the AIS data except for high-speed vessels sailing at ≥30 knots. The results indicate that by using these techniques the detection of vessel wakes from a single-point wave record is achievable under favorable weather conditions. The methods provide an option for mitigation of the impact of ship wakes in semi-enclosed water bodies.

In small island states or regions, climate change planning is frequently undertaken at a country or regional level, and it is assumed that problems are common and that remedial actions can be widely applied. Community members observe treatments such as seawalls elsewhere and demand similar interventions even though they may be inappropriate. Torres Strait lies between mainland Australia and Papua New Guinea and has communities on a diverse range of islands including low muddy, coral cay, volcanic and continental island types. Approaches to solving problems caused by changing coastal processes on these varied shorelines are discussed at scales from regional to specific sites. Torres Strait has two distinct wind seasons which influence wave-driven processes and lead to seasonally reversing alongshore sediment transport, with shoreline dynamics also controlled by coastal orientation and the beach / reef flat interactions. The low muddy islands have limited management options, requiring shore protection and elevation. Shorelines on coral cay islands and the volcanic and continental islands change shape seasonally. In these settings, planning must allow for the seasonal shoreline adjustments, with structural treatments to manage longer-term shoreline trends used only to protect high-value assets and important cultural sites where alternative management responses are not possible.

More than 3000 commercial vessels navigate through the Malamocco-Marghera Industrial Canal in Venice Lagoon, Italy in a given year, leading to an estimated annual resuspension of 1.2 x 10(6) metric tons of sediment. Hence, ship wakes contribute to the significant erosion of shoals in the central lagoon which has occurred over the last 30 years. Drawdown associated with the surface depression wave from successive ships induces sediment transport towards the shipping canal, where the cost of dredging amounts to tens of millions of Euro per year. Most ship traffic occurs near an industrial zone, resulting in substantial potential for resuspension of contaminated sediment. Thus, sediment resuspension by ship traffic in the Venice Lagoon has the potential for detrimental economic and environmental impacts. This paper illustrates the impacts of ship induced depression waves and discusses management options for mitigating those impacts, based on extensive observational data and analysis conducted in Venice Lagoon, Italy. This article helps to further the understanding of the processes that govern sediment transport along the shipping channel and employ this knowledge to develop specific management recommendations. A reduction in the navigation speed of ships, an increase in the distance between successive ships, and limiting navigation to tidal levels above 0.3 m from the local 1897 reference mean sea level can help to minimize these problems. (C) 2015 Elsevier Ltd. All rights reserved.

We demonstrate that ships of moderate size, sailing at low depth Froude numbers (0.37-0.5) in a navigation channel surrounded by shallow banks, produce depressions with depths up to 2.5 m. These depressions (Bernoulli wakes) propagate as long-living strongly nonlinear solitary Riemann waves of depression substantial distances into Venice Lagoon. They gradually become strongly asymmetric with the rear of the depression becoming extremely steep, similar to a bore. As they are dynamically similar, air pressure fluctuations moving over variable-depth coastal areas could generate meteorological tsunamis with a leading depression wave followed by a devastating bore-like feature.

An investigation based on in-situ surveys combined with remote sensing and GIS analysis revealed fast shoreline retreat on the side of a major waterway, the Malamocco Marghera Channel, in the Lagoon of Venice, Italy. Monthly and long-term regression rates caused by ship wakes in a reclaimed industrial area were considered. The short-term analysis, based on field surveys carried out between April 2014 and January 2015, revealed that the speed of shoreline regression was insignificantly dependent on the distance from the navigation channel, but was not constant through time. Periods of high water levels due to tidal forcing or storm surges, more common in the winter season, are characterized by faster regression rates. The retreat is a discontinuous process in time and space depending on the morphostratigraphy and the vegetation cover of the artificial deposits. A GIS analysis performed with the available imagery shows an average retreat of 3-4 m/yr in the period between 1974 and 2015. Digitization of historical maps and bathymetric surveys made in April 2015 enabled the construction of two digital terrain models for both past and present situations. The two models have been used to calculate the total volume of sediment lost during the period 1968-2015 (1.19x10(6) m(3)). The results show that in the presence of heavy ship traffic, ship-channel interactions can dominate the morphodynamics of a waterway and its margins. The analysis enables a better understanding of how shallow-water systems react to the human activities in the post-industrial period. An adequate evaluation of the temporal and spatial variation of shoreline position is also crucial for the development of future scenarios and for the sustainable management port traffic worldwide.

At present cruise ships use the Lido and Giudecca channels to berth at the Port of Venice, and cargo vessels use the Malamocco-Marghera channel to berth at the Marghera industrial area. Following a government decree to restrict large ship access to the Port of Venice through the Lido and Giudecca channels, the Port authority has been investigating the construction of a new channel between Marghera and the cruise terminal, to re-route all large vessels through the Malamocco lagoon entrance. Ships in the Venice Lagoon travel at low speeds with associated low depth-based Froude numbers (

A new mechanism producing onshore transport of substantial amounts of water remote from the fairway in wake waves generated by high-speed vessels is described based on high-resolution water surface profiling in Tallinn Bay, the Baltic Sea. In addition to water transported by precursor solitons, an elevation event that arrives in remote areas well after the precursors is able to carry several times as much water as the solitons and the other wave disturbances put together. When it arrives, just before the largest vessel waves, its interaction with the leading waves of wakes may produce water level set-up under groups of high ship waves. Its characteristic position at the study site, just before the highest wave group, suggests that it may be a forced disturbance created by the ship motion, the nature of which could be an almost degenerate undular bore. The backflow of this water potentially contributes to fast removal of sediment from non-equilibrium beaches by forming strong offshore-directed flow during the latter phase of the wake-wave event.

Synchronous measurements of reef flat waves and nearshore currents were made around the perimeter of three coral reef islands in the central Maldives. Nearshore current velocities were shown to be tidally modulated in most instances with maximum velocities associated with lower tidal stages. Peak currents were consistently observed on the windward and lateral flanks of island shorelines (0.3–0.4 ms− 1). The relatively low elevation of reef surfaces and medium to low energy incident wave energy (Hs ~ 0.2–0.3 m) accounts for low tidal stage peaks in velocity as this corresponds to the period when wave setup-induced current processes are maximised. Significantly, all nearshore currents were unidirectional and alongshore. The generation of unidirectional alongshore flow patterns results from island configuration which deflects flow and variations in reef geometry that control: spatial variations in wave-setup around the reef platform edge and at the island shoreline, which can drive alongshore currents; the presence of a nearshore moat that channelizes flow in the nearshore: and variations in reef geometry where topographic low points act as preferential drainage points. Results show that changes in monsoon conditions, that modulate wind and wave patterns from the west to northeast, can force substantial changes in reef platform and nearshore current flows, but that the degree of change is dependent on reef platform shape and position in the atoll. The circular study island was found to exhibit a near-complete reversal in unidirectional flow from northeast flow in the westerly monsoon to southwest flow in the northeast monsoon. However, the elongate and triangular shaped reef platforms exhibited more localised changes in flow patterns. Significantly, those shorelines that exhibit the greatest changes in shoreline currents correspond to the sections of coast that exhibit the largest morphological adjustments between seasons. Results provide significant insights for the morphodynamics of reef platform islands. In particular, the nearshore process regime is dominated by alongshore processes. Furthermore, reef platform shape and the magnitude of change in direction of wave approach to reef platforms provide critical indicators of the morphodynamic behaviour of reef platform islands.

Synchronous measurements of waves were made at six locations around a small reef platform island in the Maldives during both westerly and northeast monsoon conditions. Summary statistics of wave records indicated similar Hs values propagating onto windward and leeward reef surfaces and a distinct growth in wave height as waves shoal toward island shorelines. Waves up to 0.78 m were recorded impacting the island shoreline. Wave energy on the reef platform was strongly modulated by seasonal winds with wave energy during the westerly monsoon an order of magnitude larger than wave conditions in the northeast monsoon. Spectral analysis of wave records highlighted spatial differences in wave energy around the island. Windward reefs and shorelines are dominated by waves at wind and swell frequencies, whereas wind-wave energy is absent from leeward shorelines. Consequently, windward shorelines have up to twice the gross energy input than leeward shorelines. Results have significant implications for geomorphic processes. Longer duration and greater incident wave energy during the westerly monsoon has promoted higher growth of the western reef flat (+ 0.2 m) and more energetic shoreline runup processes have produced markedly higher western island ridges (+ 0.7 m). Incident shoreline wave processes are sufficient to entrain beach sediments during both monsoon periods although periods of active sediment mobilisation are constrained to mid- to high-tide stages. The windward–leeward gradient in shoreline wave energy is likely to drive littoral sediment flux. Seasonal modulation of the shoreline wave energy gradients account for observed oscillations in beach position around island shorelines. Large differences in incident wave energy between monsoons is considered to affect the rate of beach change around island shorelines rather than the total volumetric movement of island beaches.

High-speed ferries are known to generate wakes with unusually long periods, and occasionally large amplitudes which may serve as a qualitatively new forcing factor in coastal regions that are not exposed to a sea swell. An intrinsic feature of such wakes is their large spatial variation. We analyze the variability of wake conditions for the coasts of Tallinn Bay, the Baltic Sea, a sea area with very intense fast ferry traffic. The modelled ship wave properties for several GPS-recorded ship tracks reasonably match the measured waves in terms of both wave heights and periods. It is shown that the spatial extent of the wake patterns is very sensitive to small variations in sailing conditions. This feature leads to large variations of ship wave loads at different coastal sections with several locations regularly receiving high ship wave energy. The runup of the largest ship wakes on the beach increases significantly with an increase in wave height whereas shorter (period

Large in situ measured ship-induced depression waves (Bernoulli wakes) in the Malamocco-Marghera industrial channel of the Venice Lagoon are interpreted as long-living strongly nonlinear Riemann (simple) waves of depression. The properties of these depressions are numerically replicated using nonlinear shallow water theory and the CLAWPACK software. The further behaviour of measured depressions is analysed by means of replicating the vessel-induced disturbances with the propagation of initially smooth free waves. It is demonstrated that vessel-driven depressions of substantial height (> 0.3 m) often propagate for more than 1 km from the navigation channel into areas of the lagoon of approximately 2 m water depth. As a depression wave propagates into the lagoon, its front slope becomes gradually less steep, but the rear slope preserves an extremely steep bore-like appearance and the amplitude becomes almost independent of the initial properties of the disturbance. Analysis suggests that even modest ships in terms of their size, sailing speed, and blocking coefficient may generate deep depressions that travel as compact and steep entities resembling asymmetric solitary waves over substantial distances into shallow water adjacent to navigation channels. Their impact may substantially increase the environmental impact of ship wakes in this and similar water bodies.

Exposure to wave energy has been used to account for a range of ecological, geological and geomorphic processes in coral reef systems, but few attempts have been made to quantify spatial variations in energy at the atoll scale. This study presents results of measurements of wave energy on reef platforms across South Maalhosmadulu Atoll, Maldives and their implications for island geomorphology. The atoll has a perforated rim (37% effective aperture) and experiences predictable shifts in monsoon winds from the west (8 months) and northeast (4 months). Results show that wave energy affecting the atoll is considerably greater during the westerly monsoon. Atoll structure promotes significant changes in wave energy and wave characteristics across the atoll. Short period (3–8 s) monsoon-driven wave energy, which is significant on windward reefs, is dissipated on the peripheral reef network and the density of lagoonal patch reefs limits development of locally generated wind-wave energy across the lagoon. However, longer period swell (8–20 s) propagates through the lagoon to leeward reefs. A windward to leeward decay in wave energy is evident in the westerly monsoon, but not in the northeast monsoon, when long period swell (from the southwest) remains significant on western reefs. Net energy calculations that account for seasonal changes in wave energy across the atoll identify a steep west–east gradient that has geomorphic significance for island building. Western reefs are dominated by westerly flowing energy that is 4.5–7 times the total energy input elsewhere in the atoll. Wave energy on central reefs is balanced, whereas net energy on eastern reef platforms is dominated by eastward propagating waves. This steep energy gradient provides a physical explanation for the presence and distribution of islands on reef platforms across the atoll and provides quantitative support for the theory of Gardiner [Gardiner, J.S., 1903. The Fauna and Geography of the Maldives and Laccadives Archipelagoes. Cambridge University Press, London] to explain the prevalence of islands on the eastern atoll reef rim.

The Holocene growth of fringing and nearshore reefs on the GBR is examined. A review of data from 21 reefs indicates that most grow upon Pleistocene reef, boulder, and gravel, or sand and clay substrates, with no cored examples growing directly over rocky headlands or shores. Dated microatolls and material from shallow reef-flat cores indicate that fringing and nearshore reefs have experienced several critical growth phases since the mid-Holocene: (1) from initiation to 5500 YBP, optimum conditions for reef and reef-flat growth prevailed; (2) from 5500–4800 YBP, reef-flat progradation stalls in almost 50% of the reefs examined; (3) of reefs prograding post-4800 YBP, approximately half ceased active progradation around 3000–2500 YBP; (4) reefs prograding to present do so at rates well below mid-Holocene rates; (5) a group of nearshore reefs has established since 3000 YBP, in conditions traditionally considered poor for reef establishment and growth. Importantly, many of the reefs that appear to ha...

The Parengarenga Sandspit (Figure 1) is New Zealand's only coastal source of silica sand for glass manufacturing. Concerns about the environmental effects of sand extraction from the harbor mouth in the last two decades led the extraction companies to instigate a monitoring program. The Parengarenga beach-dune-monitoring program started in 1982; since that time cross-profiles have been surveyed twice a year from below chart datum (CD) to landward of the sparsely vegetated foredune system. This is the longest continuous record of beach profile measurement in New Zealand, and provides important information on the behavior of this coastal spit system (Parnell, 1997). The sedimentary material in Parengarenga Sandspit consists of 93.5% quartz and has a very uniform fine, sandy grain size (median 193 microns) from near shore to the beach and in the dunes.

A study of pore water exchange was undertaken within an intertidal sand flat in the Manukau Harbour, New Zealand. Measurements of water table position, and sediment saturation based on buried lysimeter cups and electrical conductivity, accompanied by an analysis of sediment characteristics were used. The level of the water table drops following exposure on the ebb tide up to 41 cm in the vicinity of drainage channels but much less over most of the sand flat. Despite the drop in water level, the surface sediments remain close to saturation throughout the period of exposure, with the extent of water table lowering being primarily influenced by topographic change close to surface drainage channels and the duration of exposure. It was determined that at all stages of exposure, the capillary fringe is well developed, intersecting with the surface, meaning the addition of a very small amount of water brings the water table to the surface. As a consequence tidal pumping and the total flux of water and gaseous exchange through the upper layers of sediment are likely to be small.

Studies of oceanographic and sedimentary processes on intertidal sand flats in an enclosed sea were undertaken to gain a better understanding of the factors controlling the mixing and dispersal of sediment bound contaminants. Field investigations included a 90 day process experiment during which wind, waves, tidal currents, tides, depth of disturbance and sand flat morphology were measured, and 27 months of sand flat profile monitoring. Sediment entrainment by strong spring tidal currents is restricted to the middle and lower regions of the sand flat which are inundated during the peak tidal flows. The upper 2–3 cm of sediment is re-worked across the middle and upper sand flat by mild storm wave events ( H s = 70 cm ), which occurred four times during the 90 day experiment. Numerous ridges and runnels in the upper sand flats are wave-formed features and are maintained by the lack of currents of sufficient magnitude to re-work the features. The ridge and runnel morphology is testimony to large infrequent storm events which re-work the sediment to depths of 20 cm. Such storms are an important mechanism for the release of contaminants and were recorded on 3 occasions in the 27 month profile record.

Whereas public participation and social impact assessment have become central themes in the resource management literature, direct action strategies by local communities have received much less attention. Direct action is likely to result when communities are affected by changes in their environment, whether these are human induced or the result of natural processes, and when agencies of the state fail to respond to the demands of the affected public in respect of such changes. Under these circumstances the local community might take action. This paper describes and analyzes community response to change in the coastal environment. Mangawhai Harbour in northern New Zealand has been subject to problems relating to the management of the coastal environment since the development of a dual inlet configuration in July 1978. By the early 1990s, conditions in the harbor had deteriorated in several important respects. On the basis of evidence indicating that restoration work may not be successful, governm...

Introduction Fringing reefs and nearshore reefs occur close to mainland or high island shores. Fringing reefs are often shore-attached, with reefal sediments extending from the fore reef to shoreline, although back reef areas can be shallowly submerged to form flooded depressions up to several hundred meters wide. However, along most of the inner Great Barrier Reef (GBR) where the majority of fringing reefs occur, relative sea level has fallen by ∼1.5 m since the mid-Holocene highstand (Section 3.4.3), and it is more typical for back reef areas to be higher than the reef crest (discussed further in Sections 7.4 and 7.5). Nearshore reefs are very close but not directly attached to mainland or high island shores, and are separated from these shorelines by back reef areas dominated by non-reefal sediments that are shallower than 10 m (Larcombe et al ., 2001). Following Darwin's (1842) classification, fringing reefs are interpreted as the first stage in a long-term evolutionary sequence, in which reef growth is initiated over a substrate on the shoreline, but later becomes separated from the shore as the underlying substrate gradually subsides and a leeward lagoon develops. Fringing reefs are thus often considered as characteristic of stable or uplifting coasts, where the geomorphological transition from fringing to barrier reef is suppressed by a lack of subsidence. However, as discussed in this chapter, the influence of slow geological subsidence on modern fringing reef growth on the Great Barrier Reef and elsewhere is often relatively small compared to that of more rapid changes in relative sea level through the Holocene.

Introduction For much of its length even the innermost reefs of the Great Barrier Reef (GBR) are beyond sight of the mainland. The main reef tract occupies the outer 30% to 50% of the shallow ( et al ., 1983), and as Lloyd (1977) noted, the geology of the shelf is closely related to the onshore geology of Queensland. For a large part of their history the GBR foundations have been part of the mainland as, during major glaciations of the Quaternary, sea level dropped to expose the shelf edge. Today, the direct influence of the mainland (including Papua New Guinea) in the form of runoff, sediment, and nutrients may be restricted to the Reef north of 18° S but along the entire coastline south to Fraser Island the sedimentary and geomorphological record of the last 8000 years or so greatly augments our understanding of the final phases in the evolution of the GBR which are the focus of this book.

Introduction Two distinctive types of islands occur on the Great Barrier Reef (GBR), the continental or high islands (hereafter referred to as high islands), and the low or reef islands (hereafter referred to as reef islands). Earlier workers defined high islands as those composed of elevated reef limestones or of non-limestone lithologies (Stoddart and Steers, 1977); on the Great Barrier Reef they are essentially continental outcrops that were separated from the mainland as the Holocene transgression flooded the continental shelf (Chapter 3). The high islands exhibit a range of topography and morphology similar to that observed along the mainland coast, which in large part reflects lithology and structure. Some high islands such as Stone Island (20° 03′ S, 149° 15′ E) are relatively low and gently sloping, but others such as Hinchinbrook Island (18° 20′ S, 146° 15′ E) are high, rugged, and drop steeply to the sea (Fig. 2.6). A good account of the relationships between mainland and high island geology and morphology is provided by Stoddart (1978). Reef islands are, in contrast, usually relatively low-lying accumulations of reef-derived sediments, portions of which may be lithified. On the GBR, reef islands have formed on reef platforms that have reached sea level after the mid-Holocene (see Sections 3.4.3 and 11.7), and which focus incident wave trains at a consistent locus over which deposition and accretion can take place (Fig. 4.11).