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Healy, T. and de Lange, W., 2014. Reliability of geomorphic indicators of littoral drift: Examples from the Bay of Plenty, New Zealand. The net direction of littoral drift can be evaluated by multiple lines of evidence, including a range of geomorphic indicators and trends in sediment characteristics. In this article, the processes that influence the longshore transport of sediment are reviewed and assessed by the types of geomorphic indicators and sediment trends that can be expected. Various proxies for measured littoral drift are used to evaluate the littoral drift in the Bay of Plenty, New Zealand. Previous studies, utilising geomorphic indicators and, to a lesser extent, sediment characteristics and simple models of longshore sediment transport, developed a conceptual model of two main littoral drift systems starting at the western and eastern margins of the Bay of Plenty and converging in the vicinity of Ohiwa Harbour, an estuary enclosed by two opposing spits within the bay. Comparison of ...

The Great Sumatra Tsunami on 26 December 2004 generated large amounts of debris and waste throughout the affected coastal region in the Indian Ocean. In Banda Aceh—Indonesia, the tsunami flows were observed carrying a thick muddy sludge that mixed with all kinds of debris from the destroyed buildings, bridges and culverts, vehicles, fallen trees, and other flotsam. This waste and debris was mostly deposited inland, but traveled both onshore and offshore. Numerical dispersal modeling is carried out to simulate the transport of debris and waste produced by the tsunamis during the event. The model solves the Lagrangian form of the transport/dispersion equations using novel particle tracking techniques. Model results show that understanding the pathway and distribution of the suspended materials and flotsam caused by tsunamis is important for a proper hazards mitigation plan and waste management action, and to minimize serious long-term adverse environmental and natural resources consequences.

The tsunami inundation flows on Banda Aceh, Indonesia reached 5 km inland during the December 26, 2004, event and devastated most of the houses, buildings, and infrastructure along the coast and killed more than 167,000 people. The overland flows from the northwest coast and the west coast collided at Lampisang village approximately 3.7 km from Ulee Lheue (northwest coast) and 6.8 km from Lhok Nga (west coast) as reported by survivors. Inundation modeling based on the nonlinear shallow-water wave equations reproduces the inundation pattern and demonstrates a colliding of the overland flows. The model suggests that wave characteristics on the northwest coast of Banda Aceh were different from those on the waves that impacted upon the west coast. The areas, which experienced higher inundation levels, did not always experience greatest overland flow speeds, and the damage areas mostly coincide with the flow speed distribution rather than the runup and inundation depth.

Disposal options for muddy dredged material, especially if lightly contaminated, is an issue facing many countries, particularly if environmental protection and adherence to the Protocols of the London Dumping Convention is a regulatory requirement. For the case of the oceanic islands of New Zealand, disposal of muddy dredged material has become an issue for the prime city of Auckland. Accordingly, it has been necessary to investigate a suitable marine disposal site outside of the territorial seas in the exclusive economic zone (EEZ). Ideal properties for such a disposal site include a near flat surface on the continental shelf, with sediments of similar textural characteristics to the material being disposed, a site of non-critical benthic ecology, water depths sufficient to enable the disposal site to be monitored (as required under the London Dumping Convention), a site experiencing low shelf currents, not affected by significant wave agitation, and a site not of cultural significance. The approach for...

Schimel, A. C. G., Healy, T. R., Johnson, D., and Immenga, D. 2010. Quantitative experimental comparison of single-beam, sidescan, and multibeam benthic habitat maps. – ICES Journal of Marine Science, 67: 1766–1779. Map comparison is a relatively uncommon practice in acoustic seabed classification to date, contrary to the field of land remote sensing, where it has been developed extensively over recent decades. The aim here is to illustrate the benefits of map comparison in the underwater realm with a case study of three maps independently describing the seabed habitats of the Te Matuku Marine Reserve (Hauraki Gulf, New Zealand). The maps are obtained from a QTC View classification of a single-beam echosounder (SBES) dataset, manual segmentation of a sidescan sonar (SSS) mosaic, and automatic classification of a backscatter dataset from a multibeam echosounder (MBES). The maps are compared using pixel-to-pixel similarity measures derived from the literature in land remote sensing. All measures agree in presenting the MBES and SSS maps as the most similar, and the SBES and SSS maps as the least similar. The results are discussed with reference to the potential of MBES backscatter as an alternative to SSS mosaic for imagery segmentation and to the potential of joint SBES–SSS survey for improved habitat mapping. Other applications of map-similarity measures in acoustic classification of the seabed are suggested.

A methodology for automatically processing the data files from an EM3000 multibeam echosounder (Kongsberg Maritime, 300 kHz) is presented. Written in MatLab, it includes data extraction, bathymetry processing, computation of seafloor local slope, and a simple correction of the backscatter along-track banding effect. The success of the latter is dependent on operational restrictions, which are also detailed. This processing is applied to a dataset acquired in 2007 in the Tamaki Strait, New Zealand. The resulting maps are compared with a habitat classification obtained with the acoustic ground-discrimination software QTC View linked to a 200-kHz single-beam echosounder and to the imagery from a 100-kHz sidescan sonar survey, both performed in 2002. The multibeam backscatter map was found to be very similar to the sidescan imagery, quite correlated to the QTC View map on one site but mainly uncorrelated on another site. Hypotheses to explain these results are formulated and discussed. The maps and t...

In recent years, mangrove expansion has become a coastal management issue in the North Island of New Zealand. Little is known about the spatial evolution and forest structure of temperate mangrove forests in New Zealand or about the associated rates of sedimentation. The extent of mangrove colonization in both a large (Waikareao Estuary) and small (Welcome Bay) embayment within Tauranga Harbour were documented. Forest structure and growth rates were described using tree height, stem density, pneumatophore density, and seedling establishment. Surface elevation changes within mangrove habitat were determined from erosion pin measurements and, on bare intertidal flats, using buried baseplates. Sediment texture and availability was also assessed using sediment traps. Results show that in 1943, mangrove vegetation covered

Despite their large numbers worldwide, surfers as a coastal interest group have largely been ignored during coastal management decision making. Surfers are, however, increasingly being considered in coastal management decisions as the social, economic, and environmental benefits of high-quality surfing breaks are realized. Examples of surfing breaks that have been improved or compromised by coastal engineering are presented here to demonstrate the fragility of surfing breaks. Integrated coastal zone management techniques are suggested as an approach to sustain recreational amenities associated with surfing breaks. Surfers can benefit from integrated coastal zone management practices that balance the coastal space requirements of various coastal user groups. This paper advocates detailed and standardized assessments of the environmental impacts that coastal activities can have on the quality of surfing waves as part of modern integrated coastal zone management practices. Baseline information must ...

Incorporating recreational surfing into coastal management practices is required to protect the seabed features and oceanographic processes that create surfing waves. A review of research-based surfing literature is undertaken to provide a summary of information available to assist in coastal management decision making around surfing breaks. The different categories of research-based surfing literature are identified as artificial surfing reef (ASR) design, ASR monitoring, ASR construction, ASR sediment dynamics, biomechanics, coastal management, economics and tourism, industry, numerical and physical modeling, surfers and waves, sociology, and physical processes. The majority of this research has been undertaken in the last decade, making it a relatively young research area. As a background for nonsurfing coastal researchers and managers, the characteristics of surfing waves and surfing breaks are described, referring to relevant literature. Wave height, peel angle, breaking intensity, and secti...

In 1992 the entrance channel through the tidal inlet to Tauranga Harbour, which is located along the Bay of Plenty littoral drift system, was deepened from 10 m to 14 m. The deepened channel has become a sediment trap for littoral drift bypassing and tidal current driven sediment transport through the inlet. Since 1992, there has been an increase in maintenance dredging requirements at the inlet, because of sand accumulation along the southeastern border of the entrance channel. Previous studies have identified an ebb tide–induced eddy operating on the eastern side of the ebb-jet as it exits the tidal gorge. In this article, the eddy system has been simulated with a validated two-dimensional hydrodynamic model, detailing time-varying current patterns over the ebb-tidal delta. Particular emphasis is placed on defining the trajectory of the eddy and evaluating its influence on the observed sedimentation patterns. The model results indicate the formation of opposing eddies on either side of the entr...

Nearshore sand transport patterns along the tideless, embayed Pirita beach, Tallinn, Estonia, have been investigated utilizing high-resolution modelling of wave processes combined with bathymetric surveys and sediment textural analyses of the nearshore sea floor. Textural analysis showed the mean grain size is about 0.12 mm. Fine sand (0.063–0.125 mm) accounts for about 77% of the sediments. Coarser-grained sand (0.28 mm) dominates along the waterline. Based upon the spatial distribution of the mean grain size and basic features of the local wave activity, properties of the Dean Equilibrium Beach Profile were determined. Alongshore sediment transport was calculated based upon a long-term time series of wave properties along the beach, and the CERC formula applied to about 500 m long beach sectors. The time series of wave fields and the properties of the local wave climate were modelled using a triple nested WAM wave model with an extended spectral range for short waves. The model is forced by open sea wind data from Kalbadagrund for the years 1981–2002. Results indicate that typical closure depth at Pirita is 2.5 m. The width and mean slope of the equilibrium profile are 250 m and 1:100, respectively. Southward transport dominates in the northern sections of the beach whereas no prevailing transport direction exists in the southern sections. This pattern has several nontrivial implications for the planning of beach protection activities.

Cross‐correlations between along‐shelf wind stress and both along‐ and cross‐shelf currents within the central Bay of Plenty, New Zealand show the circulation during spring‐summer to be highly responsive to wind events. Current meter records indicate that upwelling‐favourable wind stresses generate upwelling dynamics in both mean and fluctuating senses. Both thermistor moorings and satellite inferred temperature data record the outcropping of this cool water following upwelling‐favourable wind stresses. The upwelling circulation provides an efficient mechanism for the periodic delivery of cool (c. 80 μg litre‐1) water to the coastal zone during spring. Historical wind forcing data suggest that the wind‐forced dynamics described were responsible for a major toxic algal bloom within the Bay of Plenty during 1992–93.

Thermokarst features occur widely in the younger ice-cored moraines and kame terraces in the Dry Valleys region of Victoria Land, Antarctica Common forms are melt dolines, caves, natural bridges, and subsurface. flow. Such features typically develop in stagnant glacial ice with a low material exchange. The development of a thermokarst cave system near the Taylor Glacier during the southern summer of 1973–74 is described, and the role of the thermokarst process in land-form development in the Dry Valleys area is discussed.

The theoretical rates of deposition for fine sediments over the last 10 ka have been deduced and plotted for the Kieler Bucht. Assumptions are that the bay has remained as a closed sedimentary system, and that the fine sediments deposit in water deeper than 10 m. A sharp peak of sedimentation activity is indicated between 7.5 and 8.5 ka B.P. with low rates prior to 9.5 ka and since 6 ka. Comparison of rates obtained from dated cores extracted from different parts of the Kieler Bucht with the theoretical curve shows general conformity, and confirms that peak sedimentation rates exceeding 3 mm/a, as averaged over 100–200 years, occurred between 8 and 9 ka, with the suggestion of a minor activity peak between 3 and 4 ka. The overall consistency supports the view that the bay has acted essentially as a closed sedimentary basin during the Holocene marine transgression and subsequently.

From analysis of the densest network of echogrammes yet available for the Kieler Bucht, Western Baltic, the submarine erosional terraces have been mapped. In general these correlate well with the features mapped and described by Kolp (1976) for the adjacent Mecklenburger Bucht. The lower terraces are at - 30 m and may reach 2100 m in broadness. Compared to present day conditions, the rates of cliff retreat at the time of formation were evidently much accelerated, due possibly to harsher climatic conditions including a greater intensity of winter lake ice, frosts, wind and rain. Other terraces at - 27, - 24, - 19, and - 14 m were identified, and these are related to syngressions in the various eustatic curves applicable to the Western baltic. A hypsometric curve for the submarine terrain of the Kieler Bucht, when compared to the relative sea level curve shows that 65% of the bay was transgressed in only 700 years. Maximum sedimentation rates in the Kieler Bucht should have occurred at this time, and independent data from dated cores from Vejsnas Rinne support this prediction.

Within New Zealand, growth in the aquaculture industry has led to the diversification of aquaculture sites from more sheltered bays and harbours toward open coast locations. Coastal zone managers, along with the aquaculture industry, aim to ensure the long-term sustainability of any ‘new’ sites selected. Through targeted data collection programmes and the subsequent implementation of Geographic Information System (GIS) based models, the most suitable and sustainable locations for Aquaculture Management Areas (AMAs) can be identified. This approach is applied within the Bay of Plenty, New Zealand, with specific reference to suspended mussel (Perna canaliculus) aquaculture. Within the region, areas where maximum sustainability may be achieved make up 18% of the total area considered, with conflicting uses and other constraints accounting for 46%. Whilst further site and development specific studies are required to determine explicit carrying capacities, the effort required has been considerably reduced by eliminating unsuitable locations and identifying those where sustainability can be maximised. 2008 Elsevier Ltd. All rights reserved.

The morphological units of an ebb tidal delta were mapped and results used to evaluate the relationship between morphology and hydrodynamics, as part of an investigation into the sedimentation at the Entrance Channel at Tauranga Harbour, New Zealand. Four end-member map units (shell lag, coarse sand, medium sand, and fine sand) were identified from the sidescan sonar imagery, which was verified using seabed sediment samples and SCUBA diver observations. These four units were used in a classification scheme that consisted of 10 composite map units. The use of standardized map units helped to reduce the subjectivity involved in sidescan sonar image interpretation. The mapping scheme was used to assist in the understanding of the impact of capital dredging on the morphological evolution of an ebb tidal delta. Observed morphological changes over the ebb tidal delta were attributed to possible changes in the asymmetry of the vertical tide and residual eddy currents.

Redesign of Port Gisborne for the 21st century has encompassed a broad interdisciplinary approach. This procedure has taken into account the operational requirements of the port, effects of dredging and construction upon the benthic fauna, and wave activity within the port confines after the proposed development. Added amenity value of the development to the local community is an important ancillary redesign consideration. Initially, a major research project into the environmental impacts of the developments has been undertaken.The project, which commenced in 1996 and is still continuing, involves an iterative approach integrating the initial design and development options with the operational feasibility, construction constraints, environmental constraints, social acceptability, and economic practicality of the port; all of these require in-depth assessment to obtain the necessary planning and development approvals. This requires close liaison between the professional environmental research scientists, port management, port operation staff (pilots), construction engineers, planners, and the community interest groups.Numerical modelling of the hydrodynamics of Poverty Bay, simulating waves and current effects on the various initial designs options, and calibrated against data from a substantial field program, has been a fundamental tool. It was applied experimentally to determine the best option for the port layout, as well as to assess sedimentation impacts. Modelling results indicated a significant increase in maintenance dredging expected as a result of deepening the navigation approach channel. Because this may have an impact on the nearby sandy beach by inducing erosion, the best option for disposal of the sandy dredged material was determined to be disposal in the surf zone for subtidal beach profile renourishment. Textural analysis of the sediments trapped in the navigation channel demonstrated that they were suitable for this purpose. D 2002 Elsevier Science B.V. All rights reserved.

Previous studies have combined random-site hierarchical sampling designs with analysis of variance techniques, and grid sampling with spatial autocorrelation analysis. We illustrate that analysis techniques and sampling designs are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of variances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid designs are efficient for describing spatial pattern, and are amenable to conventional analysis. Our example deals with a continuous spatial habitat, but our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sampling are reviewed, and more efficient hierarchical approaches are identified. The distinction between biological and statistical significance in all analyses is emphasised.

Geophysical data have identified four submarine segments of the Kerepehi Fault, roughly bisecting a back-arc rift (Hauraki Rift). These segments have been traced through the shallow waters of the Firth of Thames, which lies at the southern end of the Hauraki Gulf, New Zealand. No historical or paleotsunami data are available to assess the tsunami hazard of these fault segments. Analysis of the fault geometry, combined with paleoseismic data for three further terrestrial segments of the Fault, suggest Most Credible Earthquake (MCE) moment magnitudes of 6.5-7.1. Due to the presence of thick deposits of soft sediment, and the semi-confined nature of the Firth, the MCE events are considered capable of generating tsunami or tsunami-like waves. Two numerical models (finite element and finite difference), and an empirical method proposed by Abe (1995), were used to predict maximum tsunami wave heights. The numerical models also modelled the tsunami propagation. The MCE events were found not to represent a major threat to the large metropolitan centre of Auckland City (New Zealand's largest population centre). However, the waves were a threat to small coastal communities around the Firth, including the township of Thames, and 35,000 ha of low-lying land along the southern shores of the Firth of Thames. The Abe method was found to provide a quick and useful method of assessing the regional tsunami height. However, for sources in water depths

Pyroclastic flows entering the sea played a major role in generating the largest tsunamiwaves, arising from the 1883 eruption of Krakatau, Indonesia, which caused a considerabledeath toll, most deaths resulting from the tsunamis. The potential exists for similar eventsto occur in Indonesia and New Zealand.

Infaunal bivalve molluscs on the flood tidal delta of Tauranga Harbour, north‐eastern New Zealand, were surveyed twice over a 6‐month period, with the aim of assessing shellfish resources, assessing the magnitudes of temporal and spatial variability in abundances, and identifying potentially important processes. The surveys identified a total of 31 bivalve taxa from 27 sites. Species richness per site ranged between 0 and 9, and varied greatly in space and time, as did two other measures of diversity. Extremely high densities of bivalves (>20 000 m‐2) were encountered at several sites. Densities of several abundant species varied greatly in time, as a result of recruitment pulses. The abundances of the three species that dominated the fauna (Paphies australis, Tawera spissa, and Ruditapes largillierti) had characteristic spatial scales on the order of 200 m. Comparisons of size frequency distributions for individual sites suggested that mortality or emigration in the first year of benthic life wa...

Laboratory and field experiments examining the burrowing behaviour of the estuarine infaunal bivalve Paphies australis (Bivalvia: Mesodesmatidae) were conducted in two areas of northeastern New Zealand. Field experiments examining reburial showed that when exposed on the sediment surface most P. australis were able to bury within 40 min. Slightly fewer pipi buried during high‐tide trials than during mid‐tide trials. Laboratory experiments established the ability of P. australis of various sizes to burrow up to the sediment surface after being inundated with sediment to a depth of up to 40 cm. P. australis buried under 10 cm of sediment burrowed to the surface at a slower mean rate than those buried under lesser depths of sediment, and variability in ascension rates increased with increasing burial depth. P. australis with an initial upright orientation burrowed and ascended at a greater rate than P. australis placed laterally or inverted. Though capable of ascending through as much as 50 cm of sand in lab...

A major dredging programme to deepen the shipping channels at the Port of Tauranga has seen some 5 million m3 of mainly sandy sediment dredged from the shipping channels and dumped on the adjacent inner shelf. An Environmental Impact Assessment has identified major concerns and consent granting authorities have proposed a monitoring programme.

Holocene sediment lithofacies and dispersal systems on the east Coromandel shelf, New Zealand, are mainly characterised by an accommodation-dominated regime in which autochthonous siliciclastic sediments were reworked through erosional shoreface retreat during the post-glacial marine transgression (12.0–6.5 ka). Stabilisation of sea level at its present position ca. 6.5 ka initiated onshore reworking of the autochthonous deposits into fine-grained regressive barrier and shoreface sands, while coarser sands remained offshore to form an erosional-lag inner-shelf deposit. Modern episodes of shoreface erosion rework fine and coarse autochthonous sands offshore and northwards into very large (η = 0.5–2.5 m; λ = 250–1500 m) submarine dunes. The submarine dunes are similar in form to sand ridges on the North American Atlantic shelf, but with crests striking perpendicular to both the shoreline and generating flows. Allochthonous siliciclastic lithofacies are also important aspects of east Coromandel shelf sedimentation, and are transported offshore from infilled estuary systems to form very fine-grained upper shoreface and muddy mid-shelf sands. The regional geology has a strong influence on shelf lithofacies and dispersal systems off the east Coromandel coast. Southern shelf regions are associated with deep back-arc basins which have formed major late Cenozoic depocentres for sediments sourced from the Taupo Volcanic Zone. Further north, a shallow volcanic platform extends out across the shelf and forms a barrier to any large-scale along-shelf dispersal of sediments. Consequently, lithofacies in northern shelf regions tend to be highly variable and reflect local catchment lithologies.

Beaches along the northern coast of Estonia form an interesting class of almost equilibrium , bayhead beaches located in bays deeply cut into the mainland in an essentially non-tidal, highly compartmentalised coastal landscape, and that develop mostly under the influence of wave action. These beaches, although often suffering from a certain sediment deficit, are stabilised by the postglacial land uplift. We describe the basic features of their appearance and functioning from the viewpoint of sediment transport processes. Wave action normally impacts a relatively narrow nearshore band and additionally stabilises the beaches through littoral drift of sandy sediment and gravel towards the bayheads. Eolian transport and fluvial sediment supply have typically very modest magnitude. Such beaches, in general, evolve quite slowly and may represent an almost equilibrium stage, even when the active sand mass is very limited. The concept of the equilibrium beach profile is an adequate tool for their analysis. As an example, its parameters and longshore transport patterns are evaluated for Pirita Beach based on a granulometric survey and long-term simulation of wave climate . It is demonstrated that net sand changes for such beaches can be estimated directly from the properties of the equilibrium profile, land uplift rate, and loss or gain of the dry beach area. Another type of highly dynamic equilibrium exists owing to interplay of the effects of river flow and wave action at the mouths of large rivers such as the Narva River.

More than 70 cores, a high-resolution seismic survey, and SCUBA observations provide the basis for the interpretation of depositional environments that accumulated during the Quaternary in the southeastern Tauranga Harbour area of the North Island, New Zealand. Three lithofacies comprise this sequence; in ascending order they are pumiceous sand and gravel, shelly mud and shelly sand. The pumiceous sand is interpreted as fluvial and fan deposits of Pleistocene to early Holocene age with a radiometric date of 9420 ± 100 yr BP near the top of the unit. The shelly mud represents low-energy estuarine deposition of essentially normal marine salinity in a valley-like setting. This unit dates at 8100 ± 80 yr BP. The extensive overlying shelly sand thickens seaward and represents wave-dominated shoreface conditions much like the present nearshore environment. Radiometric dating of samples within the present harbor are all between 6000 and 7000 yr BP and those seaward of the spit to Mt. Maunganui are less than 3370 ± 100 yr BP. The barrier spit that has attached to the volcanic headland began accumulating about 4000–5000 years ago.

Methodology for calculating equilibrium beach profiles for uniform sand size characteristics is extended to the case of an arbitrary distribution of sediment characteristics across the profile. The application of this method and comparison with actual profiles is posed as a means of interpreting whether the profile contains a deficit or excess of sediment and thus whether long-term shoreline recession or advancement can be anticipated. Various types of profile disequilibrium are reviewed and the significance discussed. The methodology is applied using measured profiles, sediment sizes and beach face slopes for ten sites on the Northern Island of New Zealand. One profile was documented in this study, whereas the data for the other nine were obtained from published sources. The number of sediment samples available for each profile varied from three to twelve. The agreement between the actual and calculated profiles differs considerably for the ten sites. The degree of disequilibrium is quantified by calculating the shoreline adjustment, Δy , required for the actual profile to equilibrate for depths less than 7 m, which represents the near-maximum depth available on all profiles. These shoreline adjustments ranged from − 105 m (recession) to + 159 m (advancement) with four of the ten sites having positive values. Three of the sites with negative shoreline adjustment have been, or are presently, sites of substantial sand extraction from the beach or in the nearshore waters. However, the differences between the actual and equilibrium profiles are not consistent with anticipated profile forms and/or volumes and it is thus concluded that sand mining is not responsible for most of the observed deficits. At this stage, it is not possible to state with confidence whether differences between actual and (calculated) equilibrium profiles are due to true disequilibriums or to limitations in the equilibrium beach profile methodology. Studies of the type reported here when applied to many different areas will advance the methodology and contribute to the confidence in the resulting interpretations.

This paper reviews research that has taken place on physical oceanography and sedimentology on New Zealand's estuaries and the inner shelf since c. 1967. It includes estuarine sedimentation, tidal inlets, beach morphodynamics, nearshore and inner shelf sedimentation, tides and coastal currents, numerical modelling, short‐period waves, tsunamis, and storm surges. An extensive reference list covering both published and unpublished material is included. Formal teaching and research programmes dealing with coastal landforms and the processes that shape them were only introduced to New Zealand universities in 1964; the history of the New Zealand Journal of Marine and Freshwater Research parallels and chronicles the development of physical coastal science in New Zealand, most of which has been accomplished in last 25 years.

Definitions of the geomorphic term “enclosed sea” are imprecise. Some available definitions are presented and reviewed. Based upon a quantitative morphometric ratio of {major axis length within the enclosed sea} to {entrance width}, fully “enclosed” seas are defined as having a ratio exceeding 4. If there is more than one entrance, the sea is defined as “semi-enclosed”. Those seas with major axis length to the entrance width ratios less than 4 are defined as “enclosed bays”, except if they have multiple entrances, in which case the term “semi-enclosed bay” is appropriate. Data from the world's coastal enclosed seas, defined according to the new morphometric criterion, are presented. We identify 22 enclosed seas, 6 semi-enclosed seas, 9 enclosed bays and 5 semi-enclosed bays.

Almost 3 years after the extreme 26 December 2004 tsunami event, which devastated the Banda Aceh region of Sumatra, certain coastal protection works have been planned and implemented. They comprise mainly of seawalls, breakwaters, and planting forest trees and mangroves as a wave-absorbing greenbelt. Numerical modeling of this catastrophic event was established to investigate the processes of tsunami propagation and inundation flows over the Banda Aceh coastal region, identify zones that had escaped devastation (as identified during the post event field survey) and assess possible types of coastal protection along the affected coasts. Results of the modeling showed that for protection against such a 2004-type event, huge structures ∼ 15 m high would be required, but are not economically feasible. However, mature mangroves stands may offer reasonable protection, and this option shows greater promise as an affordable solution.

The offset configuration of Tauranga tidal inlet delta system, in combination with the dredged entrance channel, hinders sediment supply to the down-drift beaches. Maintenance dredging of the entrance channel provides suitable sediment to be deposited as a nearshore berm, downdrift of the entrance channel, as a means to artificially bypass the tidal inlet and renourish the beaches of Mt Maunganui. During April and May of 2004, ∼112,000 m 3 of dredged medium sand was deposited between two nearshore dump grounds (Sites B and C), under the assumption that onshore transport would occur and act to renourish the beaches shoreward of these sites. Bathymetric and side-scan sonar monitoring showed erosion of the mounds at both sites and significant onshore dispersal at Site B clearly evident after disposal. Sub-aerial beach profile monitoring from 1999 to 2005 shows continued accretion of the sub-aerial beach from 2001 to 2005, partially in response to ongoing beach nourishment. This suggests that any reduction in sediment supply to the down-drift beaches is being successfully alleviated.