BEACH MANAGEMENT IN THE MEDITERRANEAN AND THE BLACK SEA

Proceedings of the International MEDCOAST Workshop on Beaches of the Mediterranean & the Black Sea:
Dynamics, Regeneration, Ecology & Management

24-27 October, 2002; Kuşadası, Turkey, E.Özhan (Editor)

ABSTRACTS

Abstract

This review paper discuses the problem of coastal erosion in the Mediterranean scale and provides the state-of the art of management practices. Special emphasis is given to the use of “soft methods” including beach nourishment. Environmental impacts and social implications of coastal erosion, and the means for addressing coastal erosion in the wider context of coastal management are discussed. A call is made for regional scientific collaboration for enhancing national capabilities in coastal erosion management.

Abstract

A field assessment on longshore transport and disturbance depth was carried out during a storm in an urban beach in Cadiz (SW Spain). Topographic profiles were measured by means of an electronic theodolite at the morning low tide. Samples of sand were gathered in the foreshore and analysed to obtain statistical parameters. In order to study longshore transport, natural beach sand was marked with a red fluorescent dye and injected at the mean sea level at morning low tide. During night low tide, sand tracers distribution was evaluated and samples were collected. In order to survey small topographic level variations, as well as maximum erosion and disturbance depth, rods with loose-fitting washers were inserted onto the beach surface.

Coarser and poorly sorted sediments were observed in the upper part of the intertidal area, more affected by morphodynamic processes than the low foreshore. Sand tracers suffered a great dispersion according to an offshore transport with a certain northward component. A great disturbance depth was observed. Maximum erosion and disturbance depth values were recorded in the upper part of the beach according to its greater slope.

Abstract

The aim of this study is to propose a method to evaluate the suitability of borrow material for the artificial nourishment of a beach. This method is based on the comparison between the grain size distribution of the beach's native material and the borrow material, for which a stability index (Is) can be obtained. Ignoring statistical parameters, this method can be used independently from sediment log-normality, and it can be used for materials whose grain size distributions have been obtained with a non-homogeneous sieving interval. Moreover, the proposed method allows a suitability evaluation even in all the cases in which Critical ratio (Rf _crit) cannot be computed. In this study we will analyse some nourishment cases for which the stability index has been used, either during the planning phase or during the evaluation stage.

A beach monitoring program was carried out in an urban beach in Cadiz (SW Spain). 3D topographic surveys and beach profiles were made before and after two nourishment works performed in summers 1997 and 2001. Beach morphology and evolution were greatly controlled by beach contouring conditions and were spatially ranging from North to South. So, northern sector showed a great seasonal variability; central sector, very exposed to wave attack, presented an eroded profile with small temporal variations through the year; southern sector showed a stable, dissipative profile. Beach nourishments did not experience a great longevity. Only small restoration took place during good whether conditions, especially after the construction of a submerged breakwater. Reasons for this erosion are linked to beach morphodynamics and nourishment modalities: initial dissipative profile was turned into a reflective one, characterised by plunging breakers that greatly affect bottom sediments.

Abstract

Inside the coastal morphological and sedimentary system, behind the emerged beach, the dunes through transport and sedimentation phenomena roused by wind nourished from opposite beach sediments grow up. The active sediments exchange between dunes and beach, is a distinguishing feature of the beach dunes, that act as a unique dynamic element inside the fragile and complex processes that govern a coastal system. The knowledge needs of these features is progressively increasing, as result of a greater awareness of their possible relevance and economic significance in the coastal restoration.

The work analyses the Italian perception on coastal dune safeguard as tool for the coastal risk mitigation and point up a sustainable intervention to restore the coastal dune with this aim take in Emilia Romagna region, as suitable model in Italy. This work was made inside the wide-ranging researches that are in progress on the morphological coastal dunes evolution referred to the coastal integrate risk (for erosion, flooding and subsidence) at national scale.

Abstract

The beaches located downcoast the Marina di Carrara harbour (northern Tuscany) experience severe erosion induced by the obstacle to longshore transport given by the harbour itself, and by the reduction in sediment river input from the updrift Magra River. The 6.7-kilometer-long coastal segment located between the harbour and the northern extremity of Marina dei Ronchi, is now protected by 9.3 km of hard structures. No protection was built at Marina dei Ronchi, where mean shoreline retreat rate was approximately 4 m/yr in the 1985 - 1999 period.

From 1999 to 2001 three geotextile submerged groins (from the backshore to the 3 - 4 m isobath) were built and a limited beach nourishment was performed with approximately 35.000 m³ of coarse sand and gravel (25 m³ for m of coast). Beach monitoring was performed since before the construction of the first groin, with surveys generally carried out in Winter and Autumn each year, and wave data were gathered from a gauge located offshore the study area.

Data show that this stretch of coast passed from an erosion regime, characterising the 1978 - 1999 period, to a stability one, with a beach expansion of 9.62m since 1999 and a positive sediment budget after the submerged groin system completion.

(1) Dept. of Hydraulic, Maritime, Environmental and Geotechnical Engineering, University of Padova, Via Ognissanti, 39 - 35129 Padova, Italy
Tel: +39 049 8277905 Fax: +39 049 8277988 E-mail: piero.ruol@unipd.it
⁽²⁾ Dept. of Hydraulic, Maritime, Environmental and Geotechnical Engineering, University of Padova, Via Ognissanti, 39- 35129 Padova, Italy.
Tel: +39-041 951428 E-mail: al.faedo@tin.it

Abstract

The paper in-depth describes the experimental set-up and the results obtained by some physical model tests performed in the wave flume of the IMAGE Dept. of University of Padova considering a 1:100 sloping beach protected by 7 different configurations of low-crested breakwaters. The behaviour of each structure, located within the surf zone, was studied under the action of 4 different irregular wave attacks. Aim of the study was to determine the performance of such structures, in terms of wave reflection, transmission and overtopping, for waves breaking on the foreshore (circumstance seldom considered in literature) and to suggest some new equations, of practical engineering implication.

Abstract

In this paper a study of a beach morphological response modelling protected by a low crested structure (LCS) is presented. Different test cases have been performed with the aim to evaluate the performance of the numerical model suite involved in the modelling process.

Abstract

The aeolian sand transport is investigated on Espiguette spit using Leatherman sediment traps in an empirical model validation aim. It is shown that the Bagnold (1936, 1941) model gives better results with a K constant to 1.30 and 1.81. The part of the environmental conditions is suggested in the variations of K.

Abstract

On a basis of field and numerical experiments the evolution of storm waves with groups structure from deep to shallow water are studied on the Black Sea coastal zone near Gelendzhik. It has been found that on deep water the wave group structures are determined by nonlinear properties of waves and do not depend strongly on other conditions. The simulation of characteristic wind and swell waves over the typical bottom profiles permit to eliminate the common features of wave transformation process. The revealed peculiarities of phase-amplitude-frequency structure of waves are tested concerning their influence on suspended sand transport.

Abstract

The parameterisation of suspended sediment concentration at the near bottom level (bottom boundary condition) is well-known problem of suspended sediment modelling. In coastal zone the problem is usually complicated by combined action of the surface waves and currents. The new bottom boundary condition was implemented basing on the physical analogy between unidirectional flow, waves and waves-current combination. It’s shown that the new boundary condition is in principal agreement with the traditional Shields approach. The definition of the effective shear velocity for waves on a current is considered in details. It’s also shown that the concepts of effective shear velocity and pick-up function have the same physical sense. By comparison with the field and laboratory experiments, it was shown that the new condition has the universal character and may be applied for pure flow, pure waves, and waves on a current. The boundary condition was implemented into analytical and numerical models of suspension in waves-current field. It was shown that calculated distribution of the suspended sediment concentration agrees satisfactory with experimental data. The close form method for the definition of the reference concentration is developed. It’s shown that, if the main argument of the reference concentration is a shear velocity, the method may be applied for various hydraulic conditions. Namely, the determination of the shear velocity for pure current, pure waves and for combined action of waves and current is presented, what gives the opportunity to predict the reference concentration in all these cases. The implementation of the new boundary condition to the analytical solution on concentration profile shows the satisfactory agreement with experimental data.

Mustafa Ergin, Şeref Keskin and Umran Doğan

Abstract

A large number of sediment samples were collected from beaches around Turkey to investigate whether or not these beaches contain economically important heavy mineral placer deposits. The areas under investigation covered the coasts of southwestern Black Sea (between Igneada and Istanbul Strait), southeastern Black Sea (Trabzon), northeastern Aegean Sea (Edremit Gulf and its approaches), southeastern Aegean Sea (Datca Peninsula), western Mediterranean (Finike-Fethiye, Antalya Gulf) and eastern Mediterranean (Erdemli/Icel-Mersin). Standard petrographic techniques were applied for heavy mineral analyses; however, only results on magnetic fractions (mainly magnetite) are presented here. Hand-held magnet bars were used to separate magnetite concentrations from the bulk sediment samples and the results are based on weight percentages. For most of the beaches, sediments contain normally less than 1% magnetic fractions. However, in some places in the southwestern Black Sea, southeastern Aegean Sea and the Mediterranean Sea coasts of Turkey, bulk sediments contained very high magnetic fractions (up to 52%). Geological maps suggest that wide occurences of magmatic and metamorphic rocks are the possible sources of magnetite present on modern beaches of Turkey. The studies are still going on.

Abstract

The fact that nearly 70% of the world’s population reside in or near coastal and estuarine areas, their indiscriminate exploitation and the fragile nature of these important ecosystems make necessary to take preventive measures with the practice of “environmentally-correct” policies to ensure their preservation. The aim of this paper is to discuss the development of basis and tools for helping managers and stakeholders to take suitable decisions for a better management.

Abstract

Due to the arid nature in Egypt, many tourist resorts are constructing artificial lagoons for visual, swimming, or recreational purposes. The water quality in such lagoons must be adequate to achieve the main function of these lagoons. This study provides results of a study undertaken to design an artificial lagoon west of El-Arish in Egypt. Several two dimensional models as part of the MIKE21 system were used to determine the pumping requirements and the distribution of the feeding nozzles and drains. These models included a hydrodynamic model, an advection dispersion model, a water quality model, and an Europhication model. The model results demonstrated the adequacy of the initial design with minor modifications included. The models also showed that the proposed discharge could be reduced. This study showed the importance of utilising such models prior to construction as part of the design procedure for artificial lagoons.

The water's edge, whether of a river, lake or ocean, is a great attraction; active and passive beach use is rising with increasing populations, leisure time and mobility. This puts pressure on beach resources and increases pollution levels. Through the economic value of tourism, sanitary beach quality is recognised as having real value. Health risks from poor microbial water and beach quality depend on the age and health status of the individual, the route and extent of exposure, the sources of contamination, the types and survival of microbial pathogens, the weather conditions, the density of beach/water use and the relative location and hydrodynamics at the particular beach site. Measurements of microbial water quality usually focus on data relevant to active swimmers. However, infants and young children, who are among those most vulnerable to infections from environmental sources, spend most of their time on the beach in the littoral zone where they are exposed to microorganisms in water and beach matrices, and to any aerosols generated at the sand water interface. This review considers the multiplicity of influences on the results on monitoring water quality through microbial indicators, and the littoral zone as an ecosystem in which pathogens must survive in order to be transmitted to children or other exposed individuals.

Allan T. Williams ⁽¹⁾, Anton Micallef ⁽²⁾ and Ayşen Ergin ⁽³⁾

Effective Beach Management is the art of integrating the cultural and physical environments. This paper proposes that the classic work of Sauer (1963) on landscapes (which presents models for the development of both natural and cultural landscapes) can provide a framework in which to set the factors comprising these two environments. Based on the argument that the cultural beach landscape is in part a function of the natural beach landscape, application of Sauer’s models to beach environments is suggested. A theoretical approach is given as well as examples of best practise based on some of the criteria needed for European resorts. Best practice identifies a number of tools considered essential for coastal managers include checklist procedures, education, training, monitoring and enforcement.

Abstract

The ecological features of two Ligurian beaches (NW Mediterranean) were investigated in terms of hydrodynamic forcing during spring, 2002. Sedimentary samples were collected from a beach partially protected by the structures of a tourist port, and from another exposed to wave action. The different environmental forcing was reflected by the grain size. A study of the submerged beach (from the swash zone to 2 m depth), revealed that the coarsest sands occured in the exposed beach, where the main dimensional class was gravel (31%), while in the sheltered beach the grain size was finer, dominated by the class of fine sand (39%). Moreover, we observed around the wave break point on the exposed beach (about 1 m depth), a coarsening of the grain size. The biotic features of the beaches depend on both the size structure of the sand and the direct influence of the physical and anthropic constrains. The autotrophic component was strongly inhibited by drying up and direct exposition to sunlight in the emerged beach, in both exposed and sheltered beaches, and consequently the autotrophic biomass was very low. A mechanical inhibiting action was observed for the swash zone of both beaches, where negligible values of chlorophyll-a were recorded. In the submerged beach, instead, the autotrophic biomass, in terms of chlorophyll-a concentration, was up to 0.6 µg/g, especially in the -2 m deep zone. Examining the distribution of organic matter (in terms of its main biochemical components such as proteins, carbohydrates and lipids) and the microbial populations (bacteria and fungi, for instance) linked to this trophic resource, we observed generally higher values in the submerged beach. In particular, the fraction of organic matter, more refractory to consumption (namely ca carbohydrates), showed higher values and accumulation for the sheltered beach (on average 409.9 µg/g), when compared to the exposed one (151.5 µg/g), due to the granulometric features and, probably, to the anthropic influence. Bacterial biomass was positively correlated with carbohydrates, suggesting a trophic adaptation. On the other hand, bacterial activity (in terms of frequency of duplication) was lower for the sheltered beach than for the exposed one. In the exposed beach we observed a higher trophic dynamism, with higher food value for the sedimentary organic matter (protein:carbohydrate ratio above 1), which, despite the lower abundances (meiobenthos ranging between 31 and 89 ind/10 cm² vs 5-841 ind/10 cm² in the sheltered area; macrobenthos ranging between 0 and 21.9 ind/10 cm² vs 0-36.7 ind/10 cm² in the sheltered area) supports more diversified communities. Therefore, we hypothesise that, as a consequence of the higher wave action, the exposed beach is subjected to an "enlivening action" that plays a major role in the ecological processes characterising the emerged beach ecosystem.

Abstract

An innovative checklist approach for scenic assessment in association with the utilisation of Fuzzy Logic mathematics, enabled semi-quantitative evaluation of coastal scenic assessment at five different sites. The sites were located in Malta (Marselforn and Fungus Rock), UK (Nash Point), and Turkey (Tekirova and Lara Beach). The mathematical approach enabled quantification of uncertainties, by removal of assessment uncertainties. Scenically, Fungus Rock and Tekirova were assessed as having the highest rated quality scenery.