Air, Soil and Water Research

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1 Open Access: Fll open access to this and thosands of other papers at Air, Soil and Water Research Protection and Management of the Annnziata River Moth Area (Italy) Carmelo L. Sicilia, Giandomenico Foti and Antonino Campolo Mediterranea niversity of Reggio Calaria, Department of Civil, Energetics, Environmental and Materials Engineering, Via Graziella Località Feo di Vito, 8922, Reggio Calaria, Italy. ABSTRACT: A etter nderstanding and prediction of the dynamic processes that govern the coastal zone is the topic of the crrent paper; in particlar, a deep investigation of the coastal processes that affect the shoreline dynamic and flood inndation risk is carried ot at the Annnziata river moth area (Italy). The Annnziata River is sitated in the Northern part of Reggio Calaria city; it is, at the same time, a sorce of danger and an important environmental and hydrological resorce for Reggio Calaria, since on the right side there is the city port and on the left side there is the plic each. The protection and management of coastal areas shold e spported y a deep knowledge of the interaction etween water motion and seaed topography, which affects the natral response of coastal systems to changes in external conditions and to hman interferences. This work tries to analyze the coastal morphology throgh the se of some recent models ased on spectral theory. KEY WORDS: coastal protection and management, rn-p, longshore sediment transport CITATION: Sicilia et al. Protection and Management of the Annnziata River Moth Area (Italy). Air, Soil and Water Research 203:6 7 3 doi:.437/aswr.s343. TYPE: Case Report FNDING: Athors disclose no fnding sorces. COMPETING INTERESTS: Athors disclose no potential conflicts of interest. COPYRIGHT: the athors, plisher and licensee Liertas Academica Limited. This is an open-access article distrited nder the terms of the Creative Commons CC-BY-NC 3.0 License. CORRESPONDENCE: sicilia.lca@gmail.com Introdction Coastal morphology refers to the stdy of adaptation of the coastline, driven y wave-, crrent- and wind-indced sediment transport. Coastal morphological models are indispensale and powerfl tools that allow s to set p a reliale protection and management plan for coastal areas. Morphological models are ased on varios s-models related to each of the physical phenomena involved in the dynamics of the coast sch as storms, waves, longshore sediment transport (LST), set-p, rn-p, shoreline evoltion and wave strctre interaction. LST is the natral movement of sand along coasts, and it is connected to the wave-indced crrent and to the energy dissipation cased y reaking waves in the srf zone. This energy is partially converted into potential energy as rnp, often expressed in terms of a vertical excrsion pon the mean water level. The physical description and qantification of these phenomena are freqently carried ot y means of nmerical models. 3 A sea storm is defined as a seqence of sea states in which the significant wave height H s exceeds a given threshold. Predicting and defining sea storms 4,5 plays an important role in the stdy of coastal morphology. This is also important for wave modeling, since a reliale model for a storm approximation gives s an opportnity to predict extreme waves. 6 The mtal interaction of these phenomena cold case advancement or retreat of the shoreline. Retreat is not desirale, especially where there are hman settlements or transport infrastrctres. Shoreline retreat is a natral process which is often accelerated y hman activities, 7 which throgh the constrction of coastal strctres affect the natral evoltion of the shoreline. 8,9 In these cases it is important to maintain a deep knowledge and investigation of the interaction etween wave and strctre 2 in order to avoid failre of the intervention. 3,4 Rn-p Estimation Waves approaching the coasts dissipate most of their energy y reaking across the srf zone. However, a part of this Air, Soil and Water Research 203:6 7

2 Sicilia et al energy is partially converted into potential energy as rn-p on the foreshore of the each. 4,5 Wave rn-p (defined as the time-varying location of the shoreward edge of water in front of a each) is often expressed in terms of a vertical excrsion consisting of 2 components: a sper elevation of the mean water level (MWL), called as wave setp, and flctations aot that mean, called as swash. 2 Recent stdies demonstrate that the vale of the set-p is strongly inflenced y the wave oliqity. 5 The set-p vale is inversely proportional to the dominant direction of the wave grop; conseqently, a correct estimation of the directional spreading is necessary to otain a correct evalation of the set-p. 6 The exact evalation of the rn-p and set-p and an nderstanding of the elements on which they depend are 2 fndamental aspects of the estimation of coastal risks, and of the planning and management of shore protection plans. Indeed, they are the main cases of erosion of eaches and coastal dnes, 7 9 as well as flooding of coastal areas.. Bararo et al 20 descried a proailistic approach for estimating rn-p levels. It is ased on the eqivalent trianglar storm (ETS) model proposed y Boccotti 8 and it has een applied in conjnction with the empirical relation proposed y Stockdon et al. 2 The proailistic approach has een applied to estimate the retrn period of a storm in which rn-p exceeds a fixed threshold. Frther, the mean persistence of rn-p aove a fixed threshold has een calclated. This analysis has shown that characteristics of the waves and of the each nder examination are needed for a proailistic estimation of the rn-p. The retrn period of a rn-p level that is higher than a fixed threshold is: R( R X) 2% N R( H h; θ θ/2 θ θ + θ/2) i s i i where R 2% is the rn-p vale and R (H s h; θ i θ/2 θ θ i + θ /2) is the retrn period of a sea storm in which the significant wave height H s exceeds a fixed threshold h and the dominant direction θ ranges from θ i - Δθ/ 2 to θ i + Δθ/2, which are explicitly calclated y the ETS model and it is given y the eqation 2 : R( H h; θ θ/2 θ θ + θ/2) s i i ( h; θi θ/2 θ θi + θ/2) (2) h h h h exp + exp + wα wα wβ wβ where, w α and w β are parameters that depend on the location nder examination and (h; θ i θ/2 θ θ i + θ/2) is a ase-significant wave height regression of the sea states where the direction ranges from θ i - Δθ/2 to θ i + Δθ/2. 2 () Longshore Sediment Transport Consider a sand strip of nit length extending from the reaking depth d to the shoreline, exposed to the excitation indced y the srronding wave field. Then, define µ the friction coefficient etween the moving sand layer and the each, γ s, the specific weight of the sand, γ a, the specific weight of the water, and the porosity, p. In this context, the longshore transport rate, Q s, can e estimated y the eqation 22 : Rxy Qs K gd µ γ γ ( s a) ( p) where R xy is the radiation stress tensor, g is the acceleration de to the gravity and K is an empirical coefficient. Eqation (3) can e related to the spectral characteristics of the sea waves y relying on the sea state theory. Indeed, nder the assmption of small each slope and of straight and parallel athymetric lines, Bararo et al 23 have fond that: (3) 2 Rxy ρghsδ ( d, θ0) (4) 32 in which ρ is the water density, H s is the significant wave height at the reaking depth and δ (d, θ 0 ) is a fnction of the directional spectrm S(w, θ) (w eing a non-dimensional freqency, θ a wave direction, k the wave nmer and d the water depth) with dominant direction θ 0 as given y the eqation: δ ( d, θ ) θ0 + π/2 0 θ0 π/2 0 θ0 + π/2 ( θ) 2kd S w, + sinθ cosθ dθ dw sin h( 2kd) 0 θ0 π/2 S ( w, θ) dθ dw By maniplating eqations 3 and 4 y Bararo et al 23 we otain: where: ε δ Qs ( d, θ ) γ s 32 µ γ a (5) K ε (6) 0 2 Hs ( p) Eqation (6) renders an estimate of the LST rate given the spectral characteristics of the sea state and the sediment properties of the transported material. Frther, it incldes a coefficient, K, providing an empirical correction to the calclated LST 23 gd (7) K 0.44 ln ( gt p2 /H s ) (8) 8 Air, Soil and Water Research 203:6

3 Protection and management of the annnziata river moth area (Italy) K.3-9 ln (gt p2 /H s ). (9) K.40-5 exp[.73 ln (gt p2 /H s )] () K (H s /L p ) () K exp[-83. (H s /L p )] (2) where H s is the significant wave 8 at reaking, L p is the wave length at reaking and T p the peak period. The Site and the Inpt Data The Annnziata River is sitated in the Northern part of Reggio Calaria. Reggio Calaria a small city in the Soth of the Italian Peninsla (Fig. ); its territory is characterized y a morphology that changes rapidly from mild near the coasts, to steep in the inland. The head of the river is 360 m aove sea level, in the Aspromonte Montains. The river arrives at the coastal plain after aot 20 km, a great part of its corse develops among the talelands and versants and then it flows into the Strait of Messina Sea, near the Reggio Calaria Haror. The particlar configration of the coast and the location of Sicily protect it from the severe Jonian and Tirrenian storms. In fact, only the waves, which come from a direction in the range of 240 N 345 N, affect the coast. In that range the fetches are qite limited; the longest is km and it is in the direction of 240 N. The Messina Strait is also characterized y the asence of wave data. Fortnately, in the port of Reggio Calaria, there is a wind measrement station. The river moth is next to the city port and conseqently the wind speed measred can e sed for wave prediction. The time series reports the average wind speed and direction per hor measred at 4 m elevation for the last 4 years. These eqations govern the wave growth with fetch 24 : gh gt gt ( ) z z.23 A /7 (3) (4) 3 gf.6 A s0 2 2 A p /2 gf A 2 2 A gf 6.88 A m 2 2 A 2/3 /3 (5) (6) (7) where is the wind speed at m elevation, (z) is the wind speed measred, A is the friction velocity, g is the gravity acceleration, F is the effective fetch, H s0 is the significant wave height in deep water, T p is the peak period and t m is the time reqired for waves crossing a fetch of length F nder a wind of velocity A to ecome fetch-limited. Figre 2 reports the wave height in deep water otained from Eqation (5) with its freqency of occrrence for each direction. The directions have een divided into 6 sectors of 22.5 width. As conseqence of the limited length of the fetches, small vales are otained for the significant wave height; in fact, the highest vale of the significant wave height is.2 m. Eqation (5) gives the significant wave height in deep water conditions as it is necessary to evalate the wave height and Figre. Investigated area. Air, Soil and Water Research 203:6 9

4 Sicilia et al Figre 2. Freqency of occrrence of the significant wave height and wave energy flx (N/s) for each origin direction. direction at the reaking point. If the contor lines are straight and parallel, a soltion for the shoaling is given y the following eqation: H H s s0 2π 0 0 2π 0 0 d S ( w, θ) dθ dw fixed L d S ( w, θ) dθ dw L p0 (8) where H s is the significant wave height in shallow water, S(w, θ) is the directional spectrm, d is the water depth, L p0 is the wave length in deep water and L is the wave length in shallow water. This soltion is sitale for 3D windgenerated waves and cold e accepted in the case of a largescale management plan, or cold e selected y the rater when the goal is not to design an intervention t to decide where to place it. Wave height is limited y oth depth and steepness. For a given water depth and wave period, there is a maximm height limit aove, which the wave ecomes nstale and reaks. This pper limit of wave height, called reaking wave height, is in deep water a fnction of the wave steepness; in shallow water it is a fnction oth of steepness and depth. Kamphis 25 proposed the following reaking criteria for random wind waves: H d s 0.56 exp ( 3.5λ) 2π d Hs exp ( 4 λ) Lp tan h Lp (9) (20) where λ is the each slope. Criteria (9) and (20) pertain to a plnging reaker and to a spilling reaker type, respectively. Reslts and Discssion The coast was divided in 3 sectors (Fig. 3). The direction of the simplified shorelines are as follows: Figre 3. Sketch of the coast sed in the simlation, and direction of the net longshore sediment transport. Air, Soil and Water Research 203:6

5 Protection and management of the annnziata river moth area (Italy) 0000 R(R > X) [yr] 20 D(R ) [hors] Figre 4. Rn-p and its dration verss the retrn period calclated in the sector R(R > X) [yr] 20 D(R ) [hors] Figre 5. Rn-p and its dration verss the retrn period calclated in the sector R(R > X) [yr] 20 D(R ) [hors] Figre 6. Rn-p and its dration verss the retrn period calclated in the sector 3. Air, Soil and Water Research 203:6

6 Sicilia et al Tale. Longshore sediment transport rate along the coast near the Annnziata river moth. Q Q 2 Q 3 Y 40, Y 2 60, Y m 3 /year 4687 m 3 /year 56 m 3 /year nder this schematization, a hypothesis can e adopted that considers the contor lines as straight and parallel. As the total volme of transported sediments is de to the contrition of several sea states, the longshore sediment transport is calclated y weighting the contrition of each significant wave height, with respect to the freqencies. The reslts are reported elow. As we can see, the annal amont of energy associated with a sea state is inflenced more y the fetches than y the freqency of the occrrence; in fact, for a direction etween 0 and 225, the energy is close to 0 t the freqency is not; this is de to the limited fetch corresponding to that direction. Gloally, the direction of the longshore sediment transport is from the North to the Soth (see Fig. 3) and the highest vale is in sector 2. The decrease in the longshore sediment transport rate from sector 2 to sector allowed for the formation of a stale each in an area characterized y coastal erosion. The rn-p estimation has een carried ot throgh Eqation (). In Figres 4 to 6, the rn-p and its dration are reported verss the retrn period. In Tale 2, the corresponding vales are reported for the retrn periods of, 50, 0, and 00 years. The relationship etween rn-p vale and rn-p persistence can e easily nderstood y looking at Figres 4, 5 and 6. As we can see, there is an inverse relationship etween rn-p vale and rn-p persistence. The highest vale of rn-p shold e realized when the wave direction is orthogonal to the shoreline; therefore, the highest vales are otained for sectors and 2, since shoreline directions are more exposed to waves arriving from the Northwest. Conclsions The crrent paper reports an investigation of the main coastal dynamic processes at the Annnziata river moth. Since in the Messina Strait there are no gages to measre wave climate, wind data were sed. Wave growth with wind and fetch are descried in Eqations (3) (7), and the reslts are reported in Figre 2. The wave transformation from deep to nearshore waters was made following the hypothesis that contor lines are straight and parallel, for which Eqation (8) was sed. Breaking conditions were otained throgh the Eqations (9) and (20). The coast near the river moth was divided into 3 parts in order to satisfy the hypothesis that contor lines are straight and parallel. The sketch of the coasts and the directions of the annal sediment transport rate are reported in Figre 2. The longshore sediment transport rate was evalated throgh Eqation (6) and the rn-p was estimated throgh Eqation (); the reslts are reported in Tales and 2. The direction of the longshore sediment transport is reported in Figre 3, and a plot of the rn-p and the relative dration are reported in Figres 4, 5 and 6. List of Symols λ, Beach slope;, Base (dration) of Eqivalent Trianglar Storm; d, Water depth; d, Water depth at reaking; ρ, Water density; θ, Angle etween wave direction and y axes; h, Significant wave eight threshold; g, Gravity acceleration; H s, Significant wave height; H s, Significant wave height at reaking condition; µ, Friction coefficient; F, Fetch; Q s, Longshore sediment transport vale; L, Wave length; L p, Wave length at reaking; L p, Wave length in deep water; P, Porosity; R xy, Radiation stress; R 2%, Rn-p; R, Retrn period; S, Directional spectrm; γ s, Specific weight of sediment; γ a, Specific weight of water; T p, Peak period;, Wind velocity at ; A, Wind velocity on the grond; (Z), Wind velocity;, Proaility parameter for H s ; X, threshold; k, Wave nmer; w, Non-dimensional freqency; w α, w β, Directional proaility parameter for H s. Athor Contritions CLS, GF and AC each made significant contritions to this research, and to the writing of the manscript. All athors reviewed and approved of the final manscript. Tale 2. Rn-p and its dration calclated for the retrn periods of, 50, 0, 00 years. SECTOR R Yr R 50 Yr R 0 Yr R 00 Yr R ) [h] R ) [h] R ) [h] R ) [h] Air, Soil and Water Research 203:6

7 Protection and management of the annnziata river moth area (Italy) DISCLOSRES AND ETHICS As a reqirement of plication the athors have provided signed confirmation of their compliance with ethical and legal oligations inclding t not limited to compliance with ICMJE athorship and competing interests gidelines, that the article is neither nder consideration for plication nor plished elsewhere, of their compliance with legal and ethical gidelines concerning hman and animal research participants (if applicale), and that permission has een otained for reprodction of any copyrighted material. This article was sject to lind, independent, expert peer review. The reviewers reported no competing interests. REFERENCES. Tomasicchio GR, D Alessandro F, Bararo G Malara G. General longshore transport model. Coastal Engineering. 203;7: Stockdon HF, Holman RA, Howd PA, Sallenger AH Jr. Empirical parameterization of setp, swash, and rnp. Coastal Engineering. 2006;53(7): Bararo G, Martino MC. On The Rn-p Levels And Relative Mean Persistence. Proceedings of ISOPE 7th International Offshore and Polar Engineering Conference. 2007;3: Arena F, Bararo G, Romolo A. Retrn period of a sea storm with at least two waves higher than a fixed threshold, Mathematical Prolems in Engineering. 203;: Arena F, Bararo G, Romolo A. Retrn period of a sea storm with at least two waves higher than a fixed threshold. Proceedings 28th International Conference on Offshore Mechanics and Arctic Engineering. 2009; Bararo G. Estimating design wave for offshore strctres in Italian waves. International Jornal of Maritime Engineering. 20; Bararo G, Joniche S. A Predicted Disaster, Disaster Advances. 6: Bararo G, Foti G. Shoreline ehind a reakwater: comparison etween theoretical models and field measrements for the Reggio Calaria Sea. Jornal of Coastal Research. 203;29(): Bararo G. The natral laoratory of Reggio Calaria. Proceedings of ISOPE 7th International Offshore and Polar Engineering Conference. 2007;3: Bararo G. A new expression for the direct calclation of the maximm wave force on vertical cylinders. Ocean Engineering. 2007;34(): Bararo G, Ierino B, and Martino MC. Maximm force prodced y wind generated waves on offshore maritime strctres. Proceedings of the 26th International Conference on Offshore Mechanics and Artic Engineering (OMAE). 2007; Boccotti P, Arena F, Fiamma V, Romolo A, Bararo G. Small-scale field experiment on wave forces on pright reakwaters. Jornal of Waterway, Port, Coastal and Ocean Engineering. 202;38: Boccotti P, Arena F, Fiamma V, Bararo G. Field experiment on random-wave forces on vertical cylinders. Proailistic Engineering Mechanics. 202;28: Romolo A, Malara G, Bararo G, Arena F. An analytical approach for the calclation of random wave forces on smerged tnnels. Applied Ocean Research. 2009;3: Bararo G, Foti G, Malara G. Set-p de to random waves: inflence of the directional spectrm. Proceedings of the 30th International Conference on Offshore Mechanics and Artic Engineering. 20; Boccotti P, Arena F, Fiamma V, Romolo A, Bararo G. Estimation of mean spectral directions in random seas. Ocean Engineering. 20;38(2): Rggiero P, Komar PD, McDogal WG, Marra JJ, Beach RA. Wave rnp, extreme water levels and the erosion of properties acking eaches. Jornal of Coastal Research. 200;7(2): Sallenger AH Jr. Storm impact scale for arrier islands. Jornal of Coastal Research. 2000;6(3): Tomasicchio GR, D Alessandro F, Bararo G. Composite modelling for largescale experiments on wave-dne interaction. Jornal of Hydralic Research. 20;49: Bararo G, Foti G, Malara G. A proailistic approach for the rn-p estimation. Proceedings of the 5th International Short Conference on Applied Coastal Research (SCACR) Arena F, Malara G, Bararo G, Romolo A, Ghiretti S. Long-term modelling of wave rn-p and overtopping dring sea storms. Jornal of Coastal Research. 203;29(2): Boccotti P. Wave Mechanics for Ocean Engineering, Volme ; Oxford: Elsevier Science. 23. Bararo G, Foti G, Malara G, Lca Sicilia C. A simplified formla for the calclation of the longshore sediment transport inclding spectral effects. Jornal of Coastal Research. 24. Sverdrp H, Mnk WH. Wind, sea and swell: theory of relations for forecasting. 947; Washington: Navy Hydrographic Office. 25. Kamphis JW. Effective modeling of coastal morphology. Proceedings of the th Astralasian Conference on Coastal and Ocean Engineering. 993; Air, Soil and Water Research 203:6 3