Article

Metrics for short-term coastal characterization, protection and planning decisions of Sentina Natural Reserve, Italy

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Geomorphological and sedimentological surveys of the emerged and submerged beach-dune system are fundamental for a successful management and protection strategies for coastal planning and development. In particular, these surveys can reveal if coastal areas are affected by erosion, pollution and loss of habitats under the seasonal anthropic pressure related to tourism, leisure and professional fishing, urbanisation and/or other activities impacting the coastal marine resources. In the present study we discuss the results of the multidisciplinary monitoring activities carried out within the Sentina Natural Reserve (Municipality of San Benedetto del Tronto, Adriatic side of Central Italy, at the south-eastern end of the Marche Region) proposing an exportable methodological approach. Due to the absence of buildings, the study area has not been considered in the coastal protection plan by regional and local authorities and, as a consequence, it is currently exposed to severe coastal erosion, the rate of which has been more precisely determined during the present study. This monitoring testifies that most of the seaward surface of the beach disappeared resulting in a general set back of the whole beach environment. In the last decades, several restoration strategies have been adopted to protect and restore the dunes and the back dunes habitats and the municipality also carried out an emergency action to nourish the beach, including the use of sand dredged from the nearby city harbor. With this sediment management approach, a tradeoff between safety of navigation of harbor inlet and habitat conservation of Natural Reserve have been reached, since beach nourishment can reduce coastal vulnerability and risk, even though its sustainability in the long term is still debated.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The Sentina Nature Reserve (Central Adriatic coast, Marche Region, Italy, Fig. 1), which spans about 1.7 km along the coastline, was selected as the study area since it is heavily affected by coastal erosion (Acciarri et al. 2021), with the loss of about 150 m since 1961. Established in 2004, the Reserve is included in the EU Natura 2000 network (Habitat Directive 92/43/CE); for though it is small in size, it hosts a unique treasure of biodiversity (Conti et al. 2011;Conti et al. 2013;Conti and Bracchetti 2016). ...
... The annual rainfall and temperature averages are 551 mm and 15.8 °C, respectively (Fazzini et al. 2013), with dry summer (average T = 24 °C), and rainy and moderately cold winters (average T = 7 °C). The emerged beach is made up of 11% gravel, 33% sandy gravel, 23% gravelly sand, and 33% sand (Acciarri et al. 2021). The Reserve has a flat topography and hosts residual and narrow coastal dunes (width of sand beach and coastal dune spanning 15-80 m; maximum dune elevation: 4 m). ...
Article
Climate change and human infrastructures heavily affect seashore dynamics with cascading consequences on coastal sand dunes. While there is a high number of studies conducted on plant communities, there is a lack of monitoring approaches conducted at population level. We studied the variations in spatial patterns of the population of three plant species in response to interannual coastline variation in a coastal Nature Reserve. We performed eight diachronic field observations over the course of eleven years, in which we registered the coastline variation and the position of each functional individual of the selected species. The population of the alien-naturalized and highly clonal Sporobolus pumilus demonstrated the ability to follow the interannual variations of the coastline, thus maintaining a constant distance from the seashore. In contrast, the native Polygonum maritimum and the dune-builder Thinopyrum junceum showed a progressive reduction of the distance from the seashore (− 21 m and − 16 m, respectively). However, this effect was detected only at a finer spatial scale, thus revealing the scale-dependence of this phenomenon. In addition, the spatial distribution patterns of T. junceum changed with the variation and stability of the seashore, showing spatial dispersion and aggregation patterns, respectively. Our study reveals how the plant response to the coastline variation was species-specific, probably depending on species functional strategies. Besides highlighting the importance of frequent diachronic surveys, our population-level approach may help in explaining the compositional changes observed at higher organizational level. Finally, our findings indicate that coastal erosion poses a serious threat for the conservation of dune ecosystems.
... La Pelosa Beach is one of the most touristic sandy emerged beaches of north Sardinia, suffering in the last decades from an almost continuous retreat Devoti and Silenzi 2010). Coastal erosion is a global-scale phenomenon of increasing practical and economic interest (Conti et al. 2009;Pallottini and Cappucci 2009;Manca et al. 2013;Cappucci et al. 2019;Acciarri et al. 2021) but few case studies have been focused on straits, where the distribution of sedimentary features can support an understanding of the geomorphological seabed evolution and the interpretation of geological records of similar highly dynamic shoreface deposits. ...
Full-text available
Article
This study focuses on the recent evolution of the shallow-water dunefield system off La Pelosa Beach located in the wind dominated, microtidal, asymmetrical Asinelli Strait (Stintino, NW Sardinia, Italy). The system comprises 4 zones defined by the gradual decrease of currents strength from the strait centre to more distal parts that form different bedforms. The strait centre (zone A) is a substrate-carved channel passing down-current to a vast sandy shoal characterized by subaqueous dunefield (zone B) surrounded by a sandwaves-ripples carpet (Zone C). The strait margin (zone D) is dominated by a sandy cusp the so-called La Pelosa Beach system. The extensive seagrass meadow located on the south-east side of the strait-end zone feeds the system with bioclastic-rich sands. This carbonate sedimentary load is ensured by the natural seagrass meadow retreats possibly boosted by human impacts. The sediment transport is modulated by the interaction between two opposite currents triggered by the east-incoming Greco/Levante and northwest-incoming Mistral winds. These currents experience a great variability due to multiannual fluctuation (4-6 years) of the prevailing winds activities. Such cyclicity is responsible for periodic dune migrations ands and transport from La Pelosa Beach out of the system below the active part of the submerged beach (Depth of Closure). Bedform formations (ripples, dunes and sandwaves) and migrations within the strait are the results of complex physical processes observed in modern environments but rarely described in rocks formations. The presented conceptual model can be used to recognize sediment “spillover” processes on other modern, microtidal, wind-dominated straits as well as to propose the main criteria for recognizing this strait sedimentary succession in the geological record. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6255669
... Sustainable management and conservation agendas commonly include the requirements for mapping and monitoring environmental patterns and processes because, without monitoring and data collection, stakeholders are unable to implement conservation and short-and long-term protection actions, which are the fundamentals for planning anthropogenic activities, risk recovery, and prevention actions [87]. ...
Full-text available
Article
Coastal wetlands represent particularly valuable natural resources, characterized by the interaction between their geomorphological and biological components. Their adaptation to the changing conditions depends on the rate and extent of spatial and temporal processes and their response is still not fully understood. This work aims at detecting and improving the understanding of the transition dynamics on eco-geomorphological structures in a coastal wetland ecosystem. The approach could support sustainable habitat management improving the detection and optimizing the offer of Earth Observation (EO) products for coastal system monitoring. Such course of action will strengthen evidence-based policy making, surface biophysical data sovereignty and the Space Data downstream sector through remote sensing techniques thanks to the capability of investigating larger scale and short-to-long-term dynamics. The selected case study is the Lido basin (Venice Lagoon, Italy). Our methodology offers a support in the framework of nature-based solutions, allowing the identification of ecosystem-level indicators of the surface biophysical properties influencing stability and evolution of intertidal flats on which a conceptual model is implemented. Landsat satellite imagery is used to delineate the spatial and temporal variability of the main vegetation and sediment typologies in 1990–2011. Within this period, specific anthropic activities were carried out for morphological restoration and flood protection interventions. Specifically, the lower saltmarsh shows its more fragmented part in the Baccan islet, a residual sandy spit in front of the Lido inlet. The area covered by Sarcocornia-Limonium, that triggers sediment deposition, has fluctuated yearly, from a minimum coverage of 13% to a maximum of 50%. The second decade (2001–2009) is identified as the period with major changes of halophytic and Algae-Biofilm cover typologies distribution. The power law and related thresholds, representing the patch size frequency distribution, is an indicator of the ecosystem state transition dynamics. The approach, based on multi-temporal and spatial EO analysis, is scalable elsewhere, from regional to local-to-global scale, considering the variability of climate data and anthropogenic activities. The present research also supports sustainable habitat management, improving the detection, and optimizing the offer of EO products for coastal system monitoring.
... In the study area, the Holocene wedge is formed by an accretionary prism that tends to become thinner towards the coast and offshore [47]. Moreover, this coastal area undergoes intensive bottom sediment resuspension due to strong autumn and winter storms [65][66][67]. Figure 2. Study area with the mainland geological setting and sampling stations, red and yellow dots, respectively (a); topographic section along the study area (b). The map has been generated using QGIS 3.10.4-A ...
Full-text available
Article
Sediments represent a critical compartment of marine coastal ecosystems due to the toxic and long-lasting effects of the contaminants buried therein. Here, we investigated the properties of surficial sediments in front of the Southern Marche Region coast (Central Adriatic Sea, Italy). The grain size of the surficial sediments was determined by X-ray sedigraphy. TN and OC contents were determined by elemental analysis. The concentrations of Al, Fe, Mg, K, S, Ca, Ti, P, Na, Mn, Mg, Li, As, Ba, Ga, Pb, Sr, and Zn were determined by ICP-OES to evaluate their spatial patterns and temporal trends. A Q-mode Factor Analyses was applied and resulted in the identification of three compositional facies (Padanic, Coastal, and Residual) characterized by common biogeochemical, mineralogical, sedimentological properties, transport pathway, and source. Some pollution indicators, such as the enrichment factor, the geoaccumulation index, and the pollution load index were calculated to assess the deviation from the natural background levels. The results showed a pollution by As and Ba due to the human activities in the 20th century. Furthermore, a general decreasing of Al, Ti, P, Co, Cr, Cu, Ga, Ni, Pb, Sc, V, and Y concentrations from the background levels suggested a change in the sedimentation processes during the last decades.
Article
Coastal farmers earn their living by the sea, and their willingness to pay (WTP) is particularly important for coastal zone ecological protection (CZEP). What are the specific impacts of livelihood capital and distance effect on farmers' WTP for CZEP? And what are the impact paths of these effects? To answer these questions, taking the coastal zone of the Beibu Gulf of China as an example, this paper constructs an index system based on sustainable livelihood theory, carries out research and design combined with the contingent valuation method (CVM), and conducts an empirical study on the relationship between livelihood capital, distance effect and WTP for ecological protection with the help of the entropy method, ordinary least squares (OLS) linear regression model and bootstrap method. The results show that (1) only 56.23% of the respondents have a WTP for CZEP, while 43.77% of the respondents refuse to pay. (2) The scores of each dimension of farmers' livelihood capital are as follows: risk perception (0.635) > natural capital (0.531) > financial capital (0.406) > human capital (0.299) > social capital (0.130) > physical capital (0.110), and farmers' livelihood capital and distance effect have an inverted U-shaped relationship with the WTP for ecological protection. (3) The ecological protection payments of pure farmers, type 1 farmers, type 2 farmers and nonfarmers were 151.83, 112.73, 78.87 and 95.58 RMB/year, respectively, and the influencing factors are heterogeneous. (4) We found that the mediating effects of natural capital, physical capital and financial capital are negative, social capital and risk perception are positive, while the mediating effects of human capital are not significant. Therefore, the government should establish a comprehensive management system that is cross-regional, cross-departmental, coordinated, systematic and efficient across the coastal zone.
Full-text available
Conference Paper
Abstract The Regional Natural Reserve "Sentina" stretches for circa 1.7 km along the southernmost end of the coastal area of San Benedetto del Tronto (AP), in the border with Abruzzo; it hosts one of the very few preserved costal dunes in the Marche Region. The gravelly sandy beach is still natural and free of costal defense structures, but is limited in the north by a long series of emerged barriers and in the south by a long pier (of more than 300 m length); these structures remarkably influence the retreat of the shoreline at this beach. The area was monitored for a long period (starting from year 2000) in order to analyse and quantify the modification occurred in the dry beach and the nearshore. During this time span, shoreline retreat occurred in all years. Retreat reached 27.7 m until 2006, with a local maximum of 33.5 m. In spite of artificial nourishment in 2008, in the following 6 years retreat continued at 22.2 m in average. Therefore, in 12 years wave erosion resulted in circa 50 m retreat in shoreline position; this also implied the loss of near 42.000 m2 of coastal dunes. In face of the almost null sediment feeding from Tronto River, if no relevant intervention is carried out, the Sentina area will suffer progressive coastal erosion in the near future, with severe retreat of the shoreline and destruction of the coastal dunes.
Full-text available
Conference Paper
The historical evolution of the southern Marche shoreline (between the Conero promontory and the Tronto river mouth) has been investigated and evaluated with regards to natural and anthropic changes. All the available historical maps and observations deriving from archeological and documental findings have been researched, geo-referenced and digitized in a GIS environment, in order to reconstruct the position of the shoreline at different times, especially at fluvial mouths. This allowed us to highlight that for the last two millennia anthropic interventions influenced coastal dynamics more than climate variations. For all investigated sites a close relation between shoreline fluctuations and forestation/deforestation processes was clearly identified. In addition, it emerged that river mouth progradation continued until 1930, well after the end of the "Little Ice Age" (around 1850). The above relation is particularly evident for the past two centuries, as we have accurate maps and census of forested areas for this period. During the XIX century, in spite of the warm climate having favored slope protection, widespread deforestation resulted in regular shoreline accretion (average rate of circa 4.95 m/y for the first half of the century and 1.08 m/y for the second half ). In the XX century coastal behaviour was more irregular, with substantial retreat after the 1930s: this derives almost exclusively from anthropic interventions in river basins (construction of dams, riverbed quarrying, river reshaping, abandonment of crops etc.) leading to a severe decrease in solid load. For the past few decades and at present, the most important factors driving the behavior of coastlines resulted to be the various interventions carried out along and in front of beaches to reduce erosion.
Full-text available
Article
The coasts of the Mediterranean Sea are dynamic habitats in which human activities have been conducted for centuries and which feature micro-tidal environments with about 0.40 m of range. For this reason, human settlements are still concentrated along a narrow coastline strip, where any change in the sea level and coastal dynamics may impact anthropic activities. In the frame of the RITMARE and the Copernicus Projects, we analyzed light detection and ranging (LiDAR) and Copernicus Earth Observation data to provide estimates of potential marine submersion for 2100 for 16 small-sized coastal plains located in the Italian peninsula and four Mediterranean countries (France, Spain, Tunisia, Cyprus) all characterized by different geological, tectonic and morphological features. The objective of this multidisciplinary study is to provide the first maps of sea-level rise scenarios for 2100 for the IPCC RCP 8.5 and Rahmstorf (2007) projections for the above affected coastal zones, which are the locations of touristic resorts, railways, airports and heritage sites. On the basis of our model (eustatic projection for 2100, glaciohydrostasy values and tectonic vertical movement), we provide 16 high-definition submersion maps. We estimated a potential loss of land for the above areas of between about 148 km2 (IPCC-RCP8.5 scenario) and 192 km2 (Rahmstorf scenario), along a coastline length of about 400 km.
Full-text available
Article
Coastal sand dunes are highly dynamic aeolian landforms where different spatial patterns can be observed due to the complex interactions and relationships between landforms and land cover. Sediment distribution related to vegetation types is explored here on a single ridge dune system by using an airborne hyperspectral and light detection and ranging (LiDAR) remote sensing dataset. A correlation model is applied to describe the continuum of dune cover typologies, determine the class metrics from landscape ecology and the morphology parameters, and extract the relationship intensity among them. As a main result, the mixture of different vegetation types such as herbaceous, shrubs, and trees classes shows to be a key element for the sediment distribution pattern and a proxy for dune sediment retention capacity, and the anthropic fingerprints can play an even major role influencing both ecological and morphological features. The novelty of the approach is mostly based on the synergistic use of LiDAR with hyperspectral that allowed (i) the benefit from already existing processing methods to simplify the way to obtain thematic maps and coastal metrics and (ii) an improved detection of natural and anthropic landscape.
Full-text available
Article
An application of the FHyL (field spectral libraries, airborne hyperspectral images and topographic LiDAR) method is presented. It is aimed to map and classify bedforms in submerged beach systems and has been applied to Sabaudia coast (Tirrenyan Sea, Central Italy). The FHyl method allows the integration of geomorphological observations into detailed maps by the multisensory data fusion process from hyperspectral, LiDAR, and in-situ radiometric data. The analysis of the sandy beach classification provides an identification of the variable bedforms by using LiDAR bathymetric Digital Surface Model (DSM) and Bathymetric Position Index (BPI) along the coastal stretch. The nearshore sand bars classification and analysis of the bed form parameters (e.g., depth, slope and convexity/concavity properties) provide excellent results in very shallow waters zones. Thanks to well-established LiDAR and spectroscopic techniques developed under the FHyL approach, remote sensing has the potential to deliver significant quantitative products in coastal areas. The developed method has become the standard for the systematic definition of the operational coastal airborne dataset that must be provided by coastal operational services as input to national downstream services. The methodology is also driving the harmonization procedure of coastal morphological dataset definition at the national scale and results have been used by the authorities to adopt a novel beach management technique.
Full-text available
Article
The study area is located in NW Sardinia Island (Italy), Mediterranean Sea. Sardinia is considered stable since the late Pliocene with a negligible subsidence of about 0.01 mm/y. It is therefore normally used to reconstruct the Pleistocene and Holocene sea level curves. Our research focusses on the sea-facing city of Alghero that from 1353 to 1720 was under the Spanish government. During this time, the city was renovated and new buildings edified. Dimension stones were quarried all around Alghero both in the nearby inland and along the coast. Coastal quarries were considered the most suitable for both rock quality and the easiest way to transport the quarried material by boat. The quarried rocks are late Pleistocene dune and beach sandstones deposited from the 132 ka (Marine Isotopic Stage—MIS5) to about 65 ka (MIS4). Sandstones crop out from few cm to 3 m above the present sea level and underwent several consolidation processes related to loading and marine weathering. This latter favoured dissolution and circulation of calcium carbonate which cemented the rocks. It is reported that the Spanish were looking for these “marine” sandstones for their high geotechnical characteristics. Different rules were adopted through time for the size of the dimension stones and this has allowed us to establish a quarry exploitation chronology. For example, “40 × 60 × 20” cm was the size of the dimension stones used for the Alghero Cathedral dated at 1505–1593. Nowadays most of the coastal Spanish quarry floors are 30 centimetres below mean sea level (tidal range is 30 cm). Accordingly, we infer that relative sea level from 1830 AD (and of the Little Ice Age) rose in about 200 years to the present level at the rate of about 1.4 mm/y. Considering that relative sea level rise during the Medieval warm period was of 0.6 mm/y over a period of about 400 years, we may deduce that human influence was strong enough to lead to a relative sea-level rise faster and in shorter time.
Full-text available
Article
Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway. Here data are processed by a microcontroller and then transferred to a remote data collection centre, through GSM technology. The ease of installation, the reduced power consumption and the low maintenance required, make the proposed solution able to work independently, limiting human intervention, for all the duration of the expected experimental campaign. In order to analyze the cause-effect relationship between the transported sand and the wind, the sensing structure is integrated with a multi-layer anemoscope-anemometer structure. The overall sensor network has been developed and tested in the laboratory, and its operation has been validated in field through a 48 h measurement campaign.
Full-text available
Conference Paper
The present paper describes the geological, geomorphological and hydrological characteristics of the catchment area of the Magra River, providing an estimate of the bed load sediment deliver through two methodological approaches: the first one is based on the results of field measurements conducted between 1999 and 2000 by the local authorities of Massa Carrara; the second one is based on the application of available empirical formulations. The range of the obtained results is between 35×103 and 68.5×103 m3/y which are comparable to previous investigation of WL DELFT HYDRAULICS (2006) and CAVAZZA (1977) and are higher compare to estimation derived from field measurements carried out at the Calamazza section in the upper part of the basin. Keywords: Bed load transport, Sediment delivery, ICZM, Natural capital.
Full-text available
Article
In this paper, grain size analysis on a large number of samples from a dune field within the Migliarino - San Rossore - Massaciuccoli Regional Park has been carried out in order to define the textural characterization of modern and ancient dune ridges. More than 200 samples along five transects have been collected from the backshore, the active dunes and the steady dunes up to the last recognizable dune ridge. The samples have been dry-sieved and the obtained data have been processed electronically to achieve textural parameters such as mean diameter and sorting. The results showed similar trends of the transects throughout the entire dune field. In particular, the grain size tends to decrease towards the most ancient dune ridges, showing a significant drop at the transition between active and inactive areas. The drastic decrease might be related to a possible variation of River Arno sediment discharge occurred after the XVIII century. © 2011, Societa Toscana di Scienze Naturali. All rights reserved.
Full-text available
Article
Many different kinds of classification have been applied to coasts in attempts to characterize dominant features in terms of physical or biological properties, modes of evolution, or geographic occurrence. Some of the earlier general classifications were broad in scope but lacked specificity while other specialized systems were narrowly focused, providing uneven coverage of taxonomic units for coastlines of the world. Due to more comprehensive study of coasts and the increasing availability of information, especially digital formats in GIS frameworks, integrated and systematic approaches to coastal classification are favored. The complex demands of today require sophisticated solutions to overlapping and interrelated problems in the littoral, as facilitated by organization of biophysical parameters into a coherent whole or universal scheme. The developmental approach to a new comprehensive classification system is thus proposed for the coastal fringe, a swath zone 5 to 10 km wide across the shoreline, which incorporates all important parameters necessary to categorize geomorphic units that can be mapped at meaningful scales. Consideration of coastal geomorphological properties are the theme of this approximation toward a modern taxonomic system where morphostructures are the unifying links that facilitate transition from one hierarchical level to another. The proposed approach employs differentiating criteria for hard rock (automorphic) and soft rock (allomorphic) coasts which are divided by chronometric parameters related to the antiquity of littoral landforms. Other levels of primary differentia include geodynamic-climatomorphogenic process zones, relief types (morphoregions), morphogenetic relief features, and relief elements and genetically homogeneous surfaces. Morphotypes are lower level taxons that provide examples of ingressional, egressional, and complex process-forms. The proposal for a unified system requires testing in the field and mapping at myriametric scales to update subsequent approximations.
Full-text available
Article
Three types of macro-tidal beaches, higher waves, and particularly swell produces moderate gradient (1-3°), concave, planar beaches dominated by incident, though infragravity wave energy. Moderate waves and sea conditions tend to produce lower gradient (0.5°), multi-bar (ridge and runnel) topography also attributable to infragavity standing waves. As wave energy drops still further a third type results with a high tide beach fronting tide-dominated tidal flats. This latter is not a true beach but rather a transition from beach to tidal flat. -from Author
Full-text available
Article
MATERAZZI M., GENTILI B., ARINGOLI D., FARABOLLINI P. & PAMBIANCHI G., Elements of slope and fluvial dynamics as evidence of Late Holocene climatic fluctuations in the central Adriatic sector, Italy. (IT ISSN 0391-9838, 2010). The present work aims at pointing out possible geomorphological in-dicators of climatic fluctuations detected within the Central Adriatic Re-gion of Italy and whose activation and evolution is closely connected to superficial and ground circulation of large quantities of water. It shows and analyzes several indicators in three different sample areas, which are extremely representative of the same number of physiographic units of the Central Adriatic region in Italy and of the correspondent fluvial sys-tems: mass movements and flooding processes in a wide sector of the central Apennine; fast erosion processes and landslides in the peri-Adri-atic sector; historical variations along a portion of the Adriatic shoreline. The choice of such different «environments» is not casual; in fact, the shape of a river mouth depends on the strict equilibrium among slope, river and coastal dynamics. In a given period, without significant eustatic variations, it represents the «memory» of complex environmental transformation triggered by natural or human processes within the river catchments. The collected data have been subsequently compared with those available in literature for Mediterranean Europe. The possibility to relate climatic events and geomorphological features coming from such dif-ferent areas is based on the proven congruence of their morphoclimatic settings.
Full-text available
Article
Vengono presentati i dati dei rilievi Side Scan Sonar, Multi Beam e diretti del passaggio della Pelosa, porzione sottomarina antistante la spiaggia stessa. L’obiettivo è individuare ed interpretare le strutture sedimentarie sommerse presenti ed associarle all’evoluzione della spiaggia emersa.
Full-text available
Article
Coastal dune ecosystems are characterized by a strong relationship between abiotic and biotic factors. The aim of the study is to identify the abiotic factors that mostly affect distribution and composition of plant dune communities along the coast-to-inland gradient, focusing the attention on sediment grain-size parameters, mineralogy, and dune morphology. The research was carried out on two coastal dune systems belonging to protected areas in the Mediterranean Basin, specifically in Northern and Southern Tuscany (Italy). Grain-size analysis, X-ray powder diffraction, topographic surveys, and floristic data recording were carried out along 11 transects perpendicular to the shoreline; the portion of the beach investigated is comprised within the foreshore and the backdune area. The analyses revealed some differences between the two coastal dune systems in terms of sediment parameters, mineralogy, and dune topography. The differences are mainly ascribed to the physical characteristics of the sites where the surveys were carried out. These data were matched with those provided by the vegetation sampling and then statistically processed by means of methods such as the Canonical Correlation Analysis (CCA), which showed that the mean grain-size is the most important abiotic factor that influences the composition of these coastal plant communities. These results might be considered to improve and optimize management and conservation programs for these ecosystems, since nowadays artificial dune reconstruction is a practice frequently used as a form of coastal protection. KEY WORDS: Coastal dunes, sediment grain-size, mineralogy, beach morphology, vegetation, Canonical Correlation Analysis (CCA).
Full-text available
Article
This paper describes a study to determine sediment transport processes and morphodynamics of the Tanaro River in northwestern Italy to support river management strategies. An integrated hydraulic-geomorphic approach was used to: (a) assess geology, land use and climate controls affecting sediment yield at the catchment scale; (b) evaluate changes in channel morphology and sediment transport processes; (c) model river channel change. Numerical simulations were used to evaluate the transient solution for flow and bed profile due to the propagation of the flood wave. It is concluded that Alessandria town is the most critical reach from the flooding point of view and so different design solutions were tested in order to verify whether geometric alteration of the river bed would allow for an increase in flood capacity.
Full-text available
Article
The exposed Atlantic coast of northwest Ireland supports numerous dunefields derived largely from glacigenic deposits in the area of the present continental shelf. The present-day dunes began to form about 5000 to 6000 years BP at, or just after, the mid-Holocene sea-level peak which reached a maximum of + 3 m OD on parts of the County Antrim coast. Periods of dune instability are marked by the widespread engulfment of former soil surfaces by large-scale mobile bedforms, the transport of sand inland and the formation of extensive sand sheets. -from Authors
Full-text available
Article
Bays sculptured between headlands assume a crenulate shape which fits a parabolic equation, in preference to the logarithmic spiral previously adopted. The relationships so derived apply only when bays have reached the limit of erosion or greatest indentation, when static equilibrium is said to apply. Such conditions ensue in model studies and prototype bays on islands and promontories where sediment input is known to be negligible or zero. The only input variable that dictates the resulting bay shape is the obliquity of the waves to the control line, joining the diffraction point at the upcoast headland to the downcoast limit of the beach. Equations are not available for bays still receiving sediment input, which are termed in 'dynamic equilibrium'.
Full-text available
Article
Bays as a predominant physical feature of the coastlines of the world have been recognized for some 30 years. Their plan form has received attention for over 20 years. The shape equated to a logarithmic spiral has received much attention, but is shown in this paper to be not uniformly applicable. Bays can exist in an unstable form (implying that with cessation of littoral drift they can erode back to a shape known as static equilibrium, the knowledge of whose characteristics can permit determination of their stability), or indentation, reached under conditions of no sediment supply.
Article
Multiple activities carried out on coastal areas expose marine sediments to contamination and their management has a great socio-economic importance with a high impact on economic development of coastal areas. However, there is an increasing shift towards the use of more sustainable approaches for managing ‘contaminated’ sediments. Using a case study of the Favignana Habour in Italy, this paper evaluates three approaches for the management of these sediments. The results of simulations carried out by SiteWiseTM software show that the use of contaminated sediment as filling material for Confined Disposal Facilities has lower environmental footprint than treatment and reuse of sedimentary resources on shore. The implications for these results for the development of effective policies and practices by all key stakeholders are discussed.
Article
A sediment entrainment parameter is used to calculate maximum water depth for intense bed agitation by shoaling linear waves of given height and period. Calculated limit depths agree with available laboratory measurements of water depth at an erosive wave cut into slopes of quartz and other fine sediments. Ignored variables have small effects on the agreement between calculations and laboratory measurements. On natural seasonal beaches, available measurements of seaward limit to appreciable sand level changes agree with limit depths calculated for extremely high waves expected 12 hours per year. The apparent accuracy and lack of scale effect in the calculated limit depth justify several applications in field and laboratory projects.
Article
Integrated archaeological and geological studies conducted on Mistras coastal barrier system of central Sardinia showed that it developed as transgressive systems during the final stages of the Holocene sea level rise (final stage of the Holocene Climate Optimum, about 6300 – 6000 cal y BP), and become regressive (prograding) from about 2500 cal y BP, when sea level reached the present elevation. The regression of the coast was, however, not continuous, but characterized by distinct Transgressive- Regressive phases (T-R), associated to precise climatic fluctuations, tied with global eustatic and climatic phases. The first regression occurred between 2500 and 1900 cal y BP. This time interval, known as Roman Warm, coincides with the Phoenician, Punic and Roman attendance of the west Sardinia coast. At that time, areas close to the coastal cities had to host landings and perhaps ports probably located at short distance from the shoreline. Archaeological excavations and findings have documented that in the Mistras area Punic constructed a long boulder structure (probably dated from the 4th century BCE) to better protect an incipient lagoon used as the harbour of the city of Tharros. This had the effect to modify the normal behaviour of the beach system that transformed from spit to barrier lagoon. During the second regressive phase, the well-established beach lagoon system developed quasi continuously for > 1200 y (650 and 1850 CE). This progradation started during a new warm period (Medieval) and ontinued favoured by gentle sea level fall occurred during the cold Little Ice Age time. During this time, after the abandonment of the city of Tharros and of the Sinis Peninsula, the Mistras area was poorly populated. As consequence, there was no more an active harbour and large sandy dunes developed and nourished the shore allowing a no man-influence progradation of the coast. The third stage is the current one and begun about 165 y ago (post 1850 CE) after the relative sea level rise occurred after the end of the Little Ice Age. Geological and archaeological data of western Sardinia barrier lagoon systems revealed that the Mistras barrier lagoon evolution was human in fluenced since the Punic time. The study pointed that little human ac- tivities on the coast could in fluence its natural behaviour and landscape, and that little climatic changes both positive and negative can induce progradation or erosion of the system as well.
Article
Cappucci, S.; Valentini, E.; Del Monte, M.; Paci, M.; Filipponi, F., and Taramelli, A., 2017. Detection of natural and anthropic features on small islands. In: Martinez, M.L.; Taramelli, A., and Silva, R. (eds.), Coastal Resilience: Exploring the Many Challenges from Different Viewpoints. Journal of Coastal Research, Special Issue No. 77, pp. 73–87. Coconut Creek (Florida), ISSN 0749-0208. Mapping the distribution of seabed habitats, and estimating the spatial distribution of features and biocenosis over land and the seafloor, is particularly important for the analysis of human impacts. The present paper uses an innovative image analysis method that integrates different data sources from airborne remote sensing and in situ measurements for different features, allowing the detection of ecological ‘tipping points’ both in emerged and submerged coastal environments. Results show that it is possible to differentiate between the respective roles of: first, the internal variability of the natural morphological system and second, of external forcing factors. The final evidence, however, identifies a clear signature of external forcing, but whether of anthropogenic or natural origin, is unclear. The spatial pattern of the response to anthropogenic forcing may be indistinguishable from patterns of natural variability. It is argued that this novel approach to define tipping points following anthropogenic impacts could be most valuable in the management of natural resources and the economic development of coastal areas worldwide.
Article
Beach erosion started to severely affect the Italian coast in the mid XIX century, mostly at river mouths where settlements were almost absent. When the problem reached developed areas a National law was enacted (1907) favoring defense of coastal settlements, which was mostly addressed through seawalls and revetments. In this way many coastal towns lost their beaches, which today could have a tourist and social function.In the following years, when the beach became an economic resource, groins and detached breakwaters were implemented, frequently triggering down drift erosion, therefore justifying more coastal rock structures. In some localities more than 200 groins or detached breakwaters (or both) are present in a few kilometers of coast. Coastal resilience, previously reduced by longshore urbanization, was definitely zeroed.Beach nourishment started to be carried out consistently in the '70s with quarried materials or sediment dredged in harbors or river mouths (for a total of approximately 10 M m³). In the '90s marine aggregates commenced to be used in protected and in a few unprotected beach nourishment projects. Approximately 21 M m³ have been emplaced since then.Difficulties in finding quarried material due to restrictions in opening new quarries for environmental reasons, as well as finding suitable continental shelf sediments, together with the economic crisis, caused a reduction of beach nourishment schemes in recent years.Unsatisfactory results of some projects, where sand was quickly lost or the project did not have the stakeholders' acceptance, are additional reasons for the reduction in beach nourishment projects.Designers are now much more confident with hard defenses, possibly with submerged breakwaters or groins, although many projects retrace the path of the '60s, proving that not all has been learned from past mistakes. This paper could serve as a warning for countries currently entering the process of coastal development.
Article
Changes imposed to nature by human activities and related impacts on all environmental matrices have become a critical issue. Gradually, humans began to perceive and face the magnitude of the impact of human economy on natural ecosystems and the implications for human well-being. From this perception, the concepts of natural capital and ecosystem services arose, highlighting the relationships between natural and human economy while boosting environmental conservation and management. In this framework, the definition and application of metrics and models capable of accounting for natural capital value are much needed. This is even more important when a protection regime is established (such as in the case of marine protected areas) to evaluate the efficacy of undertaken conservation measures. In this study, a biophysical and trophodynamic environmental accounting model was developed to assess the value of natural capital in marine protected areas. The model of natural capital assessment is articulated in three main steps: 1) trophodynamic analysis, providing an estimate of the primary productivity used to support the benthic trophic web within the study area, 2) biophysical accounting, providing an estimate of the biophysical value of natural capital by means of emergy accounting, and 3) monetary conversion, expressing the biophysical value of natural capital into monetary units. This conversion does not change the biophysical feature of the assessment, but instead it has the merit of allowing an easier understanding and effective communication of the ecological value of natural capital in socio-economic contexts.
Book
This original volume draws on the author's own research experiences in Ireland, Britain, France, Canada, and the United States to present a guide of coastal environments for applications of shoreline and environmental management. Topics include: long-term development of coasts, water supply and waste disposal, energy resources and coastal water management, coastal water management for recreation, coastal management of storm hazards, and managing world sea-level rise.
Article
Coastal dune ecosystems have been severely degraded as a result of excessive natural resource exploitation, urbanisation, industrial growth, and worldwide tourism. Coastal management often requires the use of vulnerability indices to facilitate the decision-making process. The main objective of this study was to develop a Mediterranean dune vulnerability index (MDVI) for sandy coasts, starting from the existing dune vulnerability index (DVI) proposed by Garcia-Mora et al. (2001) related to the oceanic coasts. Given that the Mediterranean sandy coasts are quite different from the Atlantic coasts, several adjustments and integrations were introduced. Our proposed index is based on the following five main group of factors: geomorphological conditions of the dune systems (GCD), marine influence (MI), aeolian effect (AE), vegetation condition (VC), and human effect (HE), for a total of 51 variables derived (and adapted) from the bibliography or proposed for the first time in this study. For each coastal site, a total vulnerability index, ranging from 0 (very low vulnerability) to 1 (very high vulnerability), was calculated as the unweighted average of the five partial vulnerability indices. Index computation was applied to 23 coastal dune systems of two different contexts in Italy, i.e. peninsular and continental island territories representative of the W-Mediterranean Basin, in order to compare the dune systems with different geomorphology, shoreline dynamics, and human pressure. In particular, our research addressed the following two questions: (1) Which variables are the most critical for the Italian coastal systems? (2) How can the coastal dune vulnerability index be used to develop appropriate strategies of conservation and management for these ecosystems? Cluster analysis and non-metric multidimensional scaling separated the peninsular from the insular sites, both of which were characterised by low to moderate values of vulnerability (0.32 < MDVI < 0.49). The most critical factors for the coastal systems examined in this study were marine negative influence, low stabilising ability of vegetation, and human disturbance. Hence, coastal managers are encouraged to plan specific management actions such as protection of foredunes from marine factors (particularly erosion), to promote dune formation with the reintroduction of native dune builder species and to minimise human pressure where vulnerability depends on these variables.
Article
A study of the shoreline evolution during the last two centuries along the southern portion of the Marche region (between the promontory of the Conero Mountain and the Tronto River mouth) has been carried out on the basis of historical data and taking into account the effects of both natural events and anthropogenic interventions. The research started with searching, acquiring, georeferencing and digitizing all the available maps surveyed from 1835 to the present. The above data set has been used to implement a vector geodatabase containing the successive position and shape of shorelines, with particular attention to the neighboring river mouths. Since transitional and beach deposits have been almost completely eroded during the last decades, the adoption of traditional techniques of geomorphologic and sedimentological analyses has not been possible. The results of the above analyses have been correlated with the main natural events and human interventions occurring during the considered time span. The results of this comparison highlights that the evolution of river mouths and neighboring beaches mostly depends on deforestation carried out in their hydrographic basins. In the study area, the progradation of river mouths continued after the end of the Little Ice Age (ended around 1850). Namely, it has been observed that the retreat coincided with the start of reforestation and agricultural development (in the 20's of the last century). During the following decades, further interventions, such as construction of dams and check dams, extraction of sediments from thalwegs, fillings, modifications of stream paths, abandonment of agricultural practices etc., contributed to a severe reduction of river solid load with subsequent retreat of both river mouths and beaches, thus making it necessary to protect them with artifacts.
Article
This paper investigates morphological changes in headland bay beaches with emphasis on short-term beach rotation processes, elucidating how it is affected by the planform/degree of curvature of the beach, and by the different morphodynamic characteristics of the beach systems monitored. The beaches monitored in the present study were Balneário Camboriu, Brava and Taquaras/Taquarinhas beaches. They have different lengths, degrees of curvature, and levels of exposure to the incident waves, and represent different beach types. Indentation ratio and the SL/CL ratio were measured, and beach profile surveys every 15 days were made in order to measure variations of beach volume and width for each beach. Visual wave and beach observations were recorded daily. Results indicate that morphological changes in headland bay beaches are influenced mainly by beach planform and indentation ratios, presence of rip currents and submerged bars, shoreline length, and beach type. The beach volume and with variations demonstrated that headland bay beaches have defined sectors with different behaviour, as influenced by headland impact on incident waves and longshore currents. Short-term beach rotation is manifested as out of phase variation of beach volume and width between opposite ends of a headland bay beach. Rotation amplitude of about 20 meters was observed at a dissipative beach (Balneário Camboriú), and on the reflective beach of Taquaras/Taquarinhas. Brava beach did not show clear patterns of short-term beach rotation, but there was a subdivision of the beach into two sectors with different magnitudes of sediment removal and behaviour. The occurrence of short-term beach rotation processes in some of the beaches indicates that, erosive events are often caused by a realignment of the beach shoreline in response to a shift in incident wave direction. In these cases the sediment eroded is not lost from the beach system but deposited elsewhere along the beach, and often returning to the initial location in response to a new shift in wave direction.
Article
A method is proposed for the classification of coasts with the aim of providing a tool for more correct planning and management of the coastline. The 70-km long southern coast of the Marche was subdivided into 24 stretches, each of which were described by fifteen variables: three describe the hydrodynamic and energy characteristics of the coast; four describe the evolutionary trends of the beach; seven describe the morphological and sedimentological features of the exposed beach and of the sea floor; and one quantifies the degree of human intervention. The matrix of the variables was processed using factor analysis and cluster analysis. The results of this investigation enabled us to determine the relationships between the variables and to group similar coastal tracts. This in turn allowed us to classify the coastal zones and to attribute a degree of flood vulnerability to each one. Subsequently, by relating the vulnerability to the degree of urbanization, a risk level was defined for each of the coastal stretches. -Authors
Article
In this paper we present a multitemporal analysis of the coastal system in the Sentina area (Marche Region, Central Adriatic Sea) that is characterised by a ca. 1.7 Km long sandy-gravelly beach with reduced dunal system and backshore wetland habitat. Multitemporal analyses, for the 1985-2007 timespan, have been based on ortophoto interpretation; quantitative morphometric changes were evaluated using the DSAS (Digital Shoreline Analysis System) toolbox in ArcGis®9.2. The evolution of the beach-dune system has been analysed using Surface Variation Analysis (SVA), overlapping the most representative polygons created through the chosen time interval. This analysis highlighted an erosional trend of the beach and disappearing of the dune system, with direct influence of marine water in the backshore wetland habitats. The coastal system of this area is seriously affected by a synergy of climatic and anthropic forces which, in the last 20 years, brought to a shoreline retreat of about 50 m. In this context sedimentological, stratigraphic, hydrological and hydrogeological data were analyzed and discussed, in order to characterise the system and to generate suitable scenarios for wetland restoration, dune protection and beach replenishment through a multidisciplinary approach. The results allowed to realize an emergency procedure to protect the natural habitat.
Article
There is general agreement across the scientific communities about an unmet need for a high-resolution, coastal dune multitemporal analysis. It has not been possible to construct such approach from long-time existing sources. Identification and mapping of coastal dunes in geomorphology are based on geomorphological survey, interpretation of topographic maps and aerial photos. Considerable enhancement for morphometric dune system evolution can be obtained through generation of a hierarchical approach, by means of the integration of different spectral and spatial data. This research deals with the development of a hierarchical approach to study the changes occurred in the beach-dune system of Circeo National Park (Central Italy) within approximately 30 years (1977 - 2005) in order to: (1) identify the correlation between beach and dune evolutionary trends and (2) to assess the current natural condition of the dune system, with special attention to a high vulnerable coastal stretch. The evolution of the physiographic unit has been detected through the acquisition of significant parameters: morphology of beach and dune, dynamics, anthropogenic impact,. The analysis was carried out using aerial photographs (1977-1999) and QuickBird images (2005). As a final result the relation between classification characteristics and the spatial and temporal hierarchy of dune system components is discussed. Results show that the correlation between the different parameters detected allowed the identification of the main factors acting between beach and dune system. Within the results we present and argue a framework for hierarchical dunes ecosystem classification, evolution and mapping, exemplifying that the approach is particularly valuable as a comprehensive tool for scientific analyses on behalf of environmental policy.
Article
Beach sand colour is one of the most important components of coastal landscape and particularly, a fundamental factor for beach ecology, as it influences sand temperature. Nevertheless, sand colour is often described in a subjective and qualitative manner, using non-standardised terminology and leading to noncomparable results in environmental studies which consider this aspect. Perceptive distance between colours can be measured, and perceived colour can be similarly assessed, if appropriate colour spaces are used; however, this cannot be achieved by an observer and is not frequently used in imaging systems. Several beach nourishments, performed with limited attention to colour compatibility, have changed the coastal landscape and created conflicts among stakeholders in many locations, resulting in legal controversies. The present paper compares the different "colour spaces" currently available for sand colour assessment (RGB, Munsell, CBEL*a* b*), tests some procedures for analysing sediments of different size and explains the need for using uniform colour spaces, both for environmental description and for fill sediment compatibility assessment. Case studies of beach nourishments performed in Italy are used to show the relevance of this aspect in Coastal Zone Management.
Article
The study describes the monitoring of the submerged beach of the Roman littoral of Ostia over a length of 8.3 km and a period of three years (2002 - 2005), during which, between March and July 2003, beach nourishment operations were carried out. The main objectives of the present study is to evaluate 1) the morphosedimentological variations of the submerged beach during the study period and 2) the reliability of the GPS handset (Trimble® GEO XT) used to monitoring the shoreline variation between September 2004 and September 2005. The study has allowed to reconstruct the main trends of the sedimentary dynamic processes along the littoral, the variations in shoreline position and the variations of sediment volume in order to evaluate the evolution of an artificial beach after the nourishment.
Article
A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.
Article
A Simple purely empirical ecxpression has been found which closely correlates the existing laboratory data on the measured rates of unsuspended, bedload transport of sediment in flumes with recently published data on the like transport rates in a wide variety of natural rivers. Let omega be the stream power {tau}{u} per unit bed area, and let omega_0 be the threshold value of omega at which sediment begins to be moved. Then if the flow depth is Y and the peak size, or mode, of the sediment is D, the transport rate i_b, by immersed weight, varies empirically as i_b propto (omega - omega_0)^3/2 Y-2/3 D-1/2. This is dimensionally incomplete for it omits, for instance, the excess density of the solids, which happens to be virtually constant for all the data examined. The relation can however be made dimensionless by writing i_b/(i_b)_* = biglbrackomega - omega_0/(omega -omega_0)_*bigrbrack^3/2 (Y/Y_*)-2/3 (D/D_*)-1/2, where the starred symbols refer to any standard set of values chosen from a reliable experimental plot. The above expression has so far been found to predict the average actual values within the limits of measuremental error over 10^3-fold ranges of flow depth Y and mode size D, and over a 10^4-fold range of stream power omega. When the bed material of a natural river is bimodal, the measured transport rates are found to occur, seemingly at random, between the two limiting values computed respectively for the larger and the smaller values of mode size D. A physical explanation of such an apparently general correlation poses an intriguing problem in fluid mechanics. Some qualitative clues are discussed and a tentative outline explanation is given of the general tendency of streams that flow over mobile material towards a quasi-rhythmic fluctuation of channel cross-section.
Article
Aeolian processes play a key role in the exchange of sediment between beaches and foredunes in coastal embayments. The present contribution examines the wind regimes characterizing one stretch of temperate coast (Tentsmuir, Scotland), the routing and volumes of the resultant aeolian sediment transport on the beaches and foredunes and presents a summary of wind-induced aeolian bedforms along the coast. The wind regimes identified in the Tentsmuir area include high-energy seasonal 'unimodal' (offshore or onshore) and 'bimodal' (both offshore and onshore) patterns. Landward aeolian sand transport results in foredune accretion, whereas seaward and longshore components contribute to beach growth despite reworking by waves at high water. Under the influence of the prevalent wind regimes and the resultant aeolian sediment transport, foredune accretion at Tentsmuir leads to the burial of the landward margin of the beach face.
Article
A comparison of adjacent vegetated and non-vegetated seaward-facing dune slopes illustrates some of the problems associated with stabilisation byartificial planting. Although the vegetated slopes are more sec re (‘F’ values range from 1·16 to 2·33), they have a tendency to fail as rotational slips following marine undercutting, and supply of sand to the eroding beach is greatly reduced. Also a potential for massive slab failure exists. Sediment residence time is increased from 3·5 years for loose sand faces to 27 years for planted ones. For successful stabilisation it is necessary to know both the maximum stable cliff angle and the probable magnitude of storm-induced recession.
Article
In terms of the gross first-order effects of plate tectonics, there appear to be three major classes of coasts and several subclasses, depending upon their position relative to the moving plates of the tectosphere: (1) collision coasts, that is, those on the collision edge of continents and island arcs; (2) trailing-edge coasts, that is, those on the trailing edge or noncollision side of a continent; and, (3) marginal sea coasts protected by island arcs. The trailing-edge coasts range in form from the tectonically new coasts facing beginning separation centers to the morphologically active coasts bordering the debris plains formed from the erosion products of the continents. The good coherence between certain morphologic and tectonic features of coasts was used as a guide in formulating a purely morphologic classification with tectonic implications. The morphologic classification is defined simply in terms of the width of the continental shelf and the relief of the adjacent land forms: (1) mountainous coa...
Article
Available guidance on the seaward limit to the wave-dominated beach profile has a generally inadequate basis in physical processes. The new model developed herein divides the shore-normal profile of a seasonal sand beach into three submarine zones parallel to the shoreline. The middle or shoal zone is intended to be a buffer region where expected surface waves have neither strong nor negligible effects on the sand bottom during a typical year. The shoal-zone boundaries are based on critical values of two Froude numbers giving distinct thresholds in sand mobilization by waves.With these critical values, the limiting water depths to the shoal zone are calculated from local sand characteristics and summary statistics of annual wave climate, assuming linear wave theory and an exponential cumulative distribution of wave height. The shoal zone extends seaward from the maximum depth for erosive cutting of the nearshore by yearly extreme waves to the maximum water depth for sand motion initiation by the yearly median wave condition. Available evidence on nearshore sand movement supports placement within this shoal zone of the seaward limit to appreciable bed activity due to surface waves.Suggested coastal engineering applications for the calculated shoal zone are discussed.