Consequences of Anthropic Actions in Cullera Bay (Spain)

Journal of Marine Science and Engineering

Article Consequences of Anthropic Actions in Cullera Bay (Spain)

José Ignacio Pagán , Isabel López * , Luis Bañón and Luis Aragonés Department of Civil Engineering, University of Alicante, Ctra. San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Alicante, Spain; [email protected] (J.I.P.); [email protected] (L.B.); [email protected] (L.A.) * Correspondence: [email protected]

Received: 14 February 2020; Accepted: 24 March 2020; Published: 1 April 2020

Abstract: Urbanization and anthropogenic activities have generated significant imbalances in coastal areas. This study analysed the shoreline evolution of the Bay of Cullera (Spain), characterized by strong urban and tourist pressure and with important human interventions during the last century. The evolution of the shoreline was analysed using 60 years of aerial images since the 1950s of the seabed, the maritime climate and the distribution of sediment, as well as anthropogenic actions, such as urban development or the channelling of the Júcar River through the integration of information in a geographical information system (GIS). The results showed: (i) Changes in land-use, in which the substitution of the crop and mountain areas by urban areas was mainly observed. (ii) A general increase in the beach area, although there were important periods of erosion in some points due to anthropic actions. (iii) A significant decrease in the median sediment size in the whole bay since 1987, with a current D50 of 0.125–0.180 mm. The analysis carried out has made it possible to identify trends in coastal accumulation and regression in the different sections of the sector, as well as to demonstrate the usefulness and advantages of GIS.

Keywords: beach erosion; GIS; sand; anthropic; shoreline evolution

1. Introduction Since the 1950s, coastal erosion has increased in many areas as a result of human activity [1]. Accelerated erosion, the disappearance of beaches and dunes, increased frequency of flooding and ecosystem degradation are all symptoms of an inability to provide competent coastal management [2]. In addition to these impacts of urbanization, other anthropogenic actions have strongly influenced the balance of the coastal area [3–5], such as the extraction of sand and gravel from rivers and beaches (for construction and agricultural use), the construction of dams (which prevent the maximum supply of sediments from reaching the sea), the construction of groins and jetties and the destruction of coastal dunes for the construction of infrastructures. In the context of coastal erosion, the disappearance of the dune areas deserves special attention. Coastal dunes constitute approximately three-quarters of the world’s coastline, occupying areas of transition between terrestrial and marine ecosystems [6,7]. These environments have specialized flora and fauna, and also constitute one of the most dynamic landscapes on earth, offering unique ecological services such as the filtration of large volumes of seawater, nutrient recycling, flood control and storm protection [8]. Defending against coastal erosion through dune systems is the most efficient and least costly measure [6,9]. This is because dunes are an integral part of the dynamic cycle of the coast, with a constant exchange between the two ecosystems in which it is in transition. Thus, when high-energy storms are generated that erode the beach, the dune is undermined, and this detached sand is washed offshore to the sandbanks that are responsible for dissipating the energy of the waves, causing them to break offshore.

J. Mar. Sci. Eng. 2020, 8, 240; doi:10.3390/jmse8040240 www.mdpi.com/journal/jmse J. Mar. Sci. Eng. 2020, 8, 240 2 of 14

One of the elements that can explain the coastal processes is the sediment, due to the relation that exists between their size, specific weight and the energy of the waves [10]. Therefore, it is necessary to study the evolution of the shoreline, and the transport and spatial and temporal distribution of sediments [11]. In this sense, geographic information systems (GIS), widely used in coastal risk assessment [12,13], or the evolution of cliff and seabed topography, are very useful [14,15]. Among the studies conducted, those of Rosskopf et al. [16] investigated the possible influence of natural and anthropogenic factors, especially climate variability and coastal defence structures designed on the coast of Molise. These authors concluded that the observed differences in rates of coastal change over time on the decadal to interannual scale and did not find an answer in the analysis of available data on marine meteorological conditions and indices of climate variability. Using the DSAS extension of ArcGIS software evidenced the impact of rigid structures, Molina et al. [17] found that accretion was essentially observed updrift of ports and groins and in correspondence of protection structures, especially of breakwaters. Erosion classes were observed downdrift of ports and groins and in correspondence of revetments/seawalls, and at largest river deltas, and “stability” was observed at pocket beaches and coastal areas locally stabilized by protection structures. Also, Di Paola, et al. [18] used GIS to study coastal risk in Gran Canaria, and highlighted the need for the relevant public administrations to develop a strategic approach to coastal management and sustainable development that considers socio-economic values and natural resources together. This study aimed to analyse the actions carried out in the area of study (channelling, construction on the dune systems) that have led to the current situation of this biophysical system between land, sea and air. Specifically, the evolution of the shoreline, the distribution of sediment on the seafloor and the waves were analysed to predict future behaviour in the study area, as well as the consequences that must be considered before undertaking anthropogenic actions in any area.

2. Area of Study This study was conducted in the municipality of Cullera, specifically in the so-called Bay of Cullera, which is located between the Cape of Cullera and the mouth of the Júcar River. Cullera is a municipality specially dedicated to the tourist offer with a population of 24,121 inhabitants [19], increasing it to 150,000 inhabitants in high season [20]. Except for the cliff area that constitutes the Cape of Cullera, the low, sandy coast predominates along the coastline under study. The width of the beaches differs significantly between the north and south of the river mouth, being wider from this division towards the north due to natural and anthropic factors [21]. The average width on the southern beaches is 12 m, while, on the northern beaches, the average width of the beaches is 20 m [22]. The shoreline studied extends from Los Olivos beach to San Antonio beach (Figure1). From the morphosedimentary perspective, the space considered is within a sedimentary dynamic that encompasses the entire southern sector of the Gulf of Valencia, which extends from the port of Valencia to the coast of Denia (Figure1b). This longitudinal sedimentary transport dynamic is characterized, as in the rest of the gulf, by the existence of a coastal drift from north to south [23]. The sedimentary supply that reaches the studied coast comes from the fluvial contributions of the rivers that predominate in this sector: (i) The River Túria, which affects the beaches to the north of the Cape of Cullera, and which contributes sand in strong storms to the study beaches by circumventing the Cape; and (ii) the River Júcar, which covers the rest of the beaches [24]. Geologically, the area is divided into two zones. The first zone is composed of the slope of the mountain where the land is located belongs to the upper Cretaceous. The rock formation is defined as polygenic and limestone gaps. The latter are fine-grained grey-beige or brown, sometimes with silex concretions, and maybe dolomitized. The rest of the area is presented as a pre-coastal plain occupied by sediments and flood silt corresponding to the Júcar River [25]. The main anthropogenic actions conducted in the area are [26]: J. Mar. Sci. Eng. Eng. 20202020,, 88,, x 240 FOR PEER REVIEW 3 of 14

accumulation of sediments. In the 1980s, the groin located to the north of the mouth Between 1947 and 1956, two groins of the same size were built at the mouth of the Júcar to channel • was extended. the river’s• outletIn the into same the period sea and (1947–1956), prevent it from a groin closing was due built to thebetween accumulation Racó beach of sediments. and Cap In the 1980s,Blanc the groin beach. located to the north of the mouth was extended. In the same• Taking period advantage (1947–1956), of athe groin previous was built groin, between at the end Rac óofbeach 1978, andwork Cap began Blanc on beach. a marina. • Taking advantageThus, on of Los the previousOlivos beach, groin, the at thebeginning end of of 1978, an workL-shaped began breakwater on a marina. was Thus,built, • on Los Olivoswhich beach, was the removed beginning in November of an L-shaped 1992 breakwaterbecause the was breakwater built, which was was a barrier removed to the in November 1992circulation because of the the breakwater waves that was caused a barrier erosion to the on circulation Racó beach. of theBesides, waves 18,000 that caused m3 of erosion on Racsandó beach.from Cap Besides, Blanc 18,000 was mdumped3 of sand at fromthe no Caprthern Blanc end was of dumped this beach at the so northernthat the end of this beachwaves so themselves that the waves would themselves follow the would dynamics follow naturally. the dynamics naturally. In 1994,• 40,000 In 1994, m3 of 40,000 sand wasm3 of deposited sand was along deposited the entire along length the ofentire the Raclengthó beach of the with Racó materials beach • from the Capwith Blanc materials and Los from Olivos the beaches.Cap Blanc In 1995,and Los the Olivos Racó beach beaches. promenade In 1995, wasthe rebuilt,Racó beach and 20,000 m3 ofpromenade sand was dumpedwas rebuilt, from and nearby 20,000 beaches. m3 of sand was dumped from nearby beaches. In the last• decadesIn the (1990–2019),last decades there(1990–2019), were hardly there any were modiﬁcations hardly any in themodifications infrastructures in thatthe • produced geomorphologicalinfrastructures that alterations produced in geomorphological the study area. alterations in the study area.

Figure 1.1. ((aa)) StudyStudy area area in in Valencia, Valencia, Spain. Spain. (b) ( Detailb) Detail of the of studythe study area, witharea, thewith position the position of the SIMAR of the SIMARNode used Node in theused wave in the calculations. wave calculations. (c) Location (c) ofLocation the beaches of the and beaches signiﬁcant and significant elements on elements the coast on of the coast Bay of of Cullera. the Bay (ofd) Cullera. Aerial image (d) Aerial of the image Bay of of Cullera. the Bay of Cullera.

3. Materials Materials and and Methods

3.1. Shoreline Shoreline Evolution and Land-Use Change The evolution of the shoreline was studied by means of the comparative analysis of its position from aerialaerial imagesimages fromfrom 1956 1956 to to 2019 2019 (Figure (Figure2) following2) following the the procedure procedure described described by Pag by áPagánn et al. et [27 al.]. The[27].images The images were downloadedwere downloaded from Institut from CartogrInstitut àCartogràficﬁc Valencià underValencià CC under BY 4.0 CC license BY in4.0 ECW license raster in ECWformat, raster with format, geographic with coordinategeographic system coordinate UTM system ETRS89 UTM H30N. ETRS89 The spatial H30N. resolution The spatial of theresolution images offrom the 1956 images to 2012 from is 501956 cm /pixel,to 2012 whereas is 50 cm/pixel, from 2014 whereas to 2018 is from 25 cm 2014/pixel. to The 2018 georeferencing is 25 cm/pixel. process The ® (thegeoreferencing assignment process of coordinates (the assignment to the photograms of coor rasterdinates datasets) to the wasphotograms carried out raster using datasets) ArcGIS 10.6 was. Thecarried target out image using was ArcGIS the orthophoto 10.6®. The of thetarget year image 2000. Eachwas photogramthe orthophoto was georeferencedof the year 2000. identifying Each photogram was georeferenced identifying a series of ground control points (GCP) that link locations

J. Mar. Sci. Eng. 2020, 8, 240 4 of 14 a series of ground control points (GCP) that link locations on the raster dataset with locations in the spatially referenced data (target data). For each raster, at least 50 GCP were used, which were spread over the entire image. Once the GCP were placed, the transformation of the raster was carried out using the adjust transformation. This transformation optimized the image for both global and local accuracy. The errors obtained were <0.25 m root mean square (RMS). Since all the aerial images were collected in summer and the state of the sea was relatively calm, the methodology provided optimal results for the manual vectorization of the shoreline at a scale of 1:1000. For the study of the evolution of the shoreline, the fundamentals of the DSAS program for ArcGIS [28] were used, increasing its capacities calculating the erosion-accretion surfaces. The shoreline was identified as the last visible wetland mark on the beach and vectorised using ArcGIS 10.6®. Beach area was obtained from the polygon enclosed by the input reference line and the shoreline in each period. Overlapping the layers form different periods, erosion or accretion areas were obtained. In addition, beach width can be measured by means of transects perpendicular to the coast, starting at the promenade or dune toe (used as reference line) and reaching a depth of 10 m. The intersection between transects and the shoreline enabled the measurement of the beach width in each transect for each period studied. A discrete number of transects was needed in order to analyse the shoreline changes and present the results. The separation between transects ranges from 300 m [29] in large beaches to 50 m for smaller ones [30]. The average value set by USACE [31] is 100 m and was thus used in this research, although with the GIS tool measurements can be obtained throughout the whole study area extension. Data from the CORINE Land Cover project (Coordination of Environmental Information), also known as the CLC [32], was used to analyse changes in land use. CORINE Land Cover polygons were used to identify the developed coastal area within a 1-km radius of the study beaches. The collection of land use data is based on basic terminology that distinguishes between artificial surfaces (urban fabric), agricultural areas, forest and semi-natural areas (scrub) and beaches, dunes and sandy areas. The reference date of the database is the date of acquisition of the satellite data used as basic data (1990, 2000, 2006, 2012 and 2018). Polygons in ArcGIS Geodatabase format were downloaded from scne.es under CC BY 4.0 license. For each reference year, the surface cover for each polygon was measured and grouped into the abovementioned categories. Then, a comparative analysis of the area coverage evolution of each surface was carried out.

3.2. Sediment Distribution The study of sediment distribution was performed using a GIS. From the available information, cross-sectional layers and proﬁles of the D50 and the percentage of sample retained on each sieve were generated. The data used in this work came from: (i) 1987 maps in printed format (Marine Geophysical Survey [33]), which were digitized using the ArcGIS Georeferencing tool. The root mean square error (RMS) was used to determine the error made in this process. The mean RMS value varies from 0.25 to 0.48, which implies a good accuracy considering the scale of the maps (1:5000). (ii) The Ecocartographic Study of the Provinces of Valencia and Alicante, which were provided in digital format [22]. Both types of maps contain information about the location of the sediment samples collected in the diﬀerent sampling campaigns. Each of the samples has a card associated with its characteristics: the weight of the sample collected, coordinates and depth of its location and granulometry with the weight of the sample retained on each sieve.

3.3. Maritime Climate The marine dynamics of the area, as in the rest of the Mediterranean, hardly experience tidal intensity. The importance of astronomical tides is very low, with values ranging around 0.3 m, while meteorological tides can reach values of up to 0.45 m (http://www.puertos.es). J. Mar. Sci. Eng. 2020, 8, 240 5 of 14

The analysis of the maritime climate was conducted using data from SIMAR Node 2082110 (0.17◦ W, 39.17◦ N). The data from this point were treated through the AMEVA v1.4.3 software [34], J. Mar. Sci. Eng. 2020, 8, x FOR PEER REVIEW 5 of 14 obtaining the wave height and its corresponding periods, directions and probabilities of occurrence for each of the study periods. The swell in the area is conditioned by the Cape of Cullera to the north and for each of the study periods. The swell in the area is conditioned by the Cape of Cullera to the north the mouth of the Júcar River to the south. and the mouth of the Júcar River to the south. After obtaining climate data, a study of the currents was carried out using the SMC software After obtaining climate data, a study of the currents was carried out using the SMC software (Sistema de Modelado Costero, http://www.smc.unican.es). This type of numerical model is based on a (Sistema de Modelado Costero, http://www.smc.unican.es). This type of numerical model is based description of the most important physical processes concerning bathymetry, using a series of separate on a description of the most important physical processes concerning bathymetry, using a series of submodels that simulate the main hydrodynamic mechanisms. The current two-dimensional model of separate submodels that simulate the main hydrodynamic mechanisms. The current the SMC program follows the Navier-Stokes equations [35,36]. two-dimensional model of the SMC program follows the Navier-Stokes equations [35,36]. The overall workﬂow followed in this research is shown in Figure2. The overall workflow followed in this research is shown in Figure 2.

Figure 2. Scheme of the methodologyFigure 2. Scheme followed. of the methodology followed.

4. Results Throughout the 62 years of study, a continuouscontinuous decrease in the mountain (scrub) and the agricultural area was observed (Figure 33).). InIn 1956,1956, aa largelarge partpart ofof thethe surfacesurface areaarea waswas occupiedoccupied byby mountainous areas covered with scrub (49.6%) and areasareas used for agriculture (43.5%).(43.5%). According to this decrease,decrease, thethe territory territory was was occupied occupied by by urbanized urbanized area, area, which which grew grew from from a small a small town town on the on beach the ofbeach San Antonioof San Antonio that barely that covered barely covered 1.9% of the 1.9% area of tothe reach area 37.1% to reach of the 37.1% current of the area. current Also noteworthy area. Also 2 arenoteworthy the changes are the suﬀ changesered by thesuffered beach by area, the whichbeach area, increased which by increased 147,670 mby, 147,670 which meansm2, which increasing means fromincreasing 5% of from the surface 5% of the area surface in 1956 area to 7% in 1956 in 2018. to 7% in 2018.

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Figure 3. Evolution of land use in the study area. Table shows the land use area of each class in m2. FigureFigure 3. 3. EvolutionEvolution of of land land use use in in the the study study area. area. Table Table shows shows the the land land use use area area of of each each class class in in m m2.2 . According to the evolution of the shoreline, the bay of Cullera has been defined as an area of According to the evolution of the shoreline, the bay of Cullera has been defined deﬁned as an area of growth since 1956 (Figure 4). From the beginning of the study until now (2019), the set of four growth sincesince 19561956 (Figure (Figure4). 4). From From the the beginning beginning of the of study the study until nowuntil (2019), now (2019), the set ofthe four set beachesof four beaches included in the bay have increased their surface area by 256,4992 m2, which means an average beachesincluded included in the bay in have the bay increased have increased their surface their area surface by 256,499 area by m 256,499, which m means2, which an means average an evolution average evolution rate of +1.18 m/year. However, if the evolution is analysed by periods, a balance can be evolutionrate of +1.18 rate m /ofyear. +1.18 However, m/year. ifHowever, the evolution if the is evolution analysed byis analysed periods, a by balance periods, can a be balance seen in can all thebe seen in all the beaches since 2000, with a slight increase in the beach of San Antonio (+4.6% since seenbeaches in all since the 2000, beaches with since a slight 2000 increase, with ina theslight beach increase of San in Antonio the beach (+4.6% of San since Antonio 2000). The(+4.6% shoreline since 2000). The shoreline position of each year studied and the beach width at each transect can be position2000). The of eachshoreline year studiedposition and of theeach beach year width studied ateach and transectthe beach can width be consulted at each in transect Supplementary can be consulted in Supplementary File S1. consultedFile S1. in Supplementary File S1.

Figure 4. (a) Beach width for each transect in 1956 and 2019. (b), (c), (d) and (e), Linear regression rates Figure 4. (a) Beach width for each transect in 1956 and 2019. (b), (c), (d) and (e), Linear regression Figure(LRR) for 4. each(a) Beach period width of study for each in m /transectyr. Since in the 1956 periods and 1956–19772019. (b), ( andc), ( 1989–2000d) and (e), are Linear each regression composed rates (LRR) for each period of study in m/yr. Since the periods 1956–1977 and 1989–2000 are each ratesof only (LRR) two dates,for each End period Point of Rates study (EPR) in m/ wereyr. presented.Since the periods 1956–1977 and 1989–2000 are each composed of only two dates, End Point Rates (EPR) were presented. composed of only two dates, End Point Rates (EPR) were presented. Analysing each of the beaches separately, Cap Blanc beach was the only one that remained stable Analysing each of the beaches separately, Cap Blanc beach was the only one that remained throughoutAnalysing the each study of period, the beaches although separately, it suffered Cap significant Blanc beach variations was the between only one 1977–2000, that remained with a stable throughout the study period, although it suffered significant variations between 1977–2000, stablemaximum throughout erosion ratethe study of 6.3 period, m/year although (1997–1989) it suffered and a maximum significant accretion variations rate ofbetween+8.5 m /1977–2000,year in the with a maximum erosion− rate of −6.3 m/year (1997–1989) and a maximum accretion rate of +8.5 periodwith a 1989–2000.maximum Sanerosion Antonio rate beachof −6.3 was m/year the one (1997–1989) that has su ffandered a themaximum greatest variationsaccretion rate above of all+8.5 in m/year in the period 1989–2000. San Antonio beach was the one that has suffered the greatest m/year in the period 1989–2000. San Antonio beach was the one that has suffered the greatest variations above all in the period 1956–2000, in which the beach surface area increased by 192,413 variations above all in the period 1956–2000, in which the beach surface area increased by 192,413

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J. Mar. Sci. Eng. 2020, 8, x FOR PEER REVIEW 7 of 14 the period 1956–2000, in which the beach surface area increased by 192,413 m2, which, considering the length of the beach, means an average increase of 84 m in beach width. As for the other two m2, which, considering the length of the beach, means an average increase of 84 m in beach width. As beaches (Racó and Los Olivos), the main variations occurred between 1977 and 1992. These variations, for the other two beaches (Racó and Los Olivos), the main variations occurred between 1977 and which produced the accretion of Los Olivos beach and the erosion of Racó beach, occurred due to 1992. These variations, which produced the accretion of Los Olivos beach and the erosion of Racó the construction and subsequent removal of an L-shaped breakwater for the creation of a marina, beach, occurred due to the construction and subsequent removal of an L-shaped breakwater for the which caused a destabilisation of the whole. Both beaches have remained stable since the removal of creation of a marina, which caused a destabilisation of the whole. Both beaches have remained stable the breakwater, with an average beach width of 70 m on Racó beach and 73 m on Los Olivos beach since the removal of the breakwater, with an average beach width of 70 m on Racó beach and 73 m (Figure5). on Los Olivos beach (Figure 5).

FigureFigure 5. 5. ShorelineShoreline evolutionevolution and beach width in in ( (aa)) 1956, 1956, (b (b) )1977, 1977, (c ()c )1985, 1985, (d ()d 2000,) 2000, (e ()e 2010) 2010 and and (f) (f2019.) 2019. Also, Also, the the change change from from crops crops fields ﬁelds to tourba urbanizednized areas areas from from 1956 1956 to to 2000 2000 can can be be appreciated. appreciated.

TheThe analysisanalysis ofof sedimentsediment distributiondistribution showedshowed aa significantsignificant decreasedecrease inin medianmedian sedimentsediment sizesize acrossacross thethe baybay (Figure(Figure6 ).6). Thus, Thus, in in 1987, 1987, there there was was a a predominance predominance of of fine fine sand sand (0.180–0.250 (0.180–0.250 mm), mm), exceptexcept forfor the the area area around around the the mouth mouth of of the the J úJúcarcar river, river, where where there there was was a a significant significant accumulation accumulation ofof siltsilt (0.02–0.002(0.02–0.002 mm)mm) andand clayclay (<(<0.002 0.002 mm). mm). However,However, inin 2006, 2006, thethe distribution distribution waswas muchmuch moremore homogeneous,homogeneous, withwith finefine sandsand alongalong thethe wholewhole baybay with with some some occasional occasional sources sources of of slightly slightly thicker thicker sandsand (0.250–0.350(0.250–0.350 mm).mm). TheseThese areasareas werewere mainlymainly foundfound aroundaround LosLos OlivosOlivos beachbeach andand nextnext toto thethe mouthmouth of of the the J úJúcarcar River. River. By By analysing analysing the the di ffdifferenerent proportionst proportions of sedimentof sediment sizes sizes in depthin depth (Figure (Figure7), it7), has it beenhas been found found that the that smaller the smaller sizes accumulate sizes accumulate outside outside the depth the of depth closure of ( closure5.69 m, ( obtained≈ 5.69 m, ≈ accordingobtained toaccording Aragon étos, etAragonés, al. [37]) irregularly,et al. [37]) whileirregularly, the larger while sizes the (0.180larger mm sizes and (0.180 0.250 mm mm) and show 0.250 a clearmm) tendency show a clear to remain tendency in the to first remain 4–5 m in of the the firs profilet 4–5 and m of not the change profile position. and not A change clear example position. can A beclear found example at Rac canó beach, be found where at the Racó predominant beach, where sizes the near predominant the shore are sizes those near of the the shore larger are sediments. those of the larger sediments.

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Figure 6. Distribution of the median sediment size in 1987 (a) and 2006 (b). Figure 6. DistributionFigure 6. ofDistribution the median of sediment the median size sedimentin 1987 (a size) and in 2006 1987 ( (ba).) and 2006 (b).

a b 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% a 2 0.24 b 2 8% 26% 53% 12% 2 Beach profile 0.24 2 8%8% 26%27% 53%51% 12%13% 1 Beach profile 0.23 D50 profile 1 8%9% 27%31% 51%46% 13%12% 1 D50 profile 0.23 DoC 1 9%11% 31%34% 46%41% 12%11% DoC 0 0.22 0 11%12% 34%36% 41%38% 11%11% 0 0.22 0 12%13% 36%37% 38%37% 11%10% -1 0.21 -1 13%13% 37%38% 37%36% 10%10% -1 0.21 -1 13%14% 38%42% 36%32% 10%9% -2 0.20 -2 14%15% 42%46% 32%28% 9%8% -2 0.20 -2 15%16% 46% 54% 28% 20% 8%7% -3 0.19 -3 16%22% 54%51% 20%19% 7%6% -3 0.19 -3 22%26% 51%49% 19%17% 6%5% -4 0.18 -4 26%31% 49%47% 17%14% 5%5% -4 0.18 -4 31%34% 47%47% 14%12% 5%4% D50(mm) 34% 47% 12% 4%

Elevation (m) -5 0.17 Elevation (m) -5 37% 46% 11% 4% DoC: -5.69 m D50(mm)

Elevation (m) -5 0.17 Elevation (m) -5 37%39% 46%44% 11%11% 4%3% DoC:D : 0.138-5.69 mmm 50 39% 44% 11% 3% -6 D50: 0.138 mm 0.16 -6 39% 43% 12% 3% -6 0.16 -6 39%39% 43%43% 12%12% 3%3% -7 0.15 -7 39%38% 43%44% 12%12% 3%3% -7 0.15 -7 38%37% 44% 12%12% 3%4% 37% 44% 12% 4% -8 0.14 -8 36% 44% 12% 4% -8 0.14 -8 33%36% 41%44% 14%12% 6%4%3% 33% 41% 14% 6% 3% -9 0.13 -9 33% 40% 14% 6% 3% -9 0.13 -9 33%32% 40%41% 14%14% 6%6% 3%4% -10 32%31% 41% 14%13% 6%7% 4%4% -10 0.12 -10 31% 41% 13% 7% 4% -10 0.12 0 200 400 600 800 1000 1200 1400 1600 1800 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 200 400 600 800 1000 1200 1400 1600 1800 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Distance offshore (m) 0.0039 0.063 0.125 0.18 0.25 0.35 0.5 > 0.500 Distance offshore (m) 0.0039 0.063 0.125 0.18 0.25 0.35 0.5 > 0.500 Figure 7. (a) Beach profile and median sediment size (D50) profile with depth of closure (DoC) FigureFigure 7. ((aa)) BeachBeach proﬁle profile and and median median sediment sediment size size (D50 )(D proﬁle50) profile with depthwith depth of closure of closure (DoC) marked. (DoC) marked. (b) Grain size distribution with depth. marked.(b) Grain (b size) Grain distribution size distribution with depth. with depth.

AsAs far far asasas thethethe waves waveswaves are areare concerned, concerned,concerned, as asas shown shownshown in Figureinin FigureFigure8, the 8,8, mostthethe mostmost common commoncommon directions directionsdirections were thosewerewere thosethosebetween betweenbetween the NE thethe and NENE the andand ESE thethe (both ESEESE (both(both inclusive), inclusivinclusiv whilee),e), whilewhile the waves thethe waveswaves from from thefrom NNE, thethe NNE,NNE, SE, SSE SE,SE, and SSESSE S andand were SS werepracticallywere practicallypractically insigniﬁcant, insignificant,insignificant, with an withwith average anan averageaverage accumulated accumulatedaccumulated value of valuevalue 6.5%. ofof The 6.5%.6.5%. most TheThe common mostmost commoncommon wave heights wavewave heightswereheights those werewere below thosethose 1 belowbelow m with 11 periodsmm withwith betweenperiodsperiods betweenbetween 5–6 s, which 55–6–6 s, indicatess, whichwhich indicatesindicates that this isthatthat an thisthis area isis with anan areaarea relatively withwith relativelyrelativelycalm coastal calmcalm dynamics coastalcoastal dynamics throughoutdynamics throughoutthroughout the year. On thethe average, yeyear.ar. OnOn 56% average,average, of the 56%56% waves ofof werethethe waveswaves less than werewere 0.5-m lessless than high,than 0.5-m0.5-mand 29.2% high,high, were andand 29.2% between29.2% werewere 0.5-m betweenbetween and 1-m 0.5-m0.5-m high andand (Figure 1-m1-m hi9hi).ghgh The (Figure(Figure probability 9).9). TheThe of probabilityprobability occurrence ofof of occurrenceoccurrence wave height ofof wavewaveand direction heightheight andand was direction practicallydirection waswas stable practicallypractically during the stablestable periods duringduring analysed. thethe periodsperiods However, analysed.analysed. the last However,However, period (2008–2019) thethe lastlast periodperiodstands (2008–2019) out,(2008–2019) in which standsstands a variation out,out, inin of whichwhich the probability aa variationvariation of ofof occurrence thethe probabilityprobability was observed, ofof occurrenceoccurrence mainly: waswas (i) observed,observed, The NE mainly:wavesmainly: increased (i)(i) TheThe NENE 6.4% waveswaves concerning increasedincreased the 6.4%6.4% average concerningconcerning of the thethe rest averageaverage of the periods. ofof thethe restrest There ofof thethe was periods.periods. a decrease ThereThere in waswas the awavea decreasedecrease heights inin belowthethe wavewave 0.5 m,heightsheights but heights belowbelow between0.50.5 m,m, butbut 0.5 heightsheights m and 1.5betweenbetween m increased. 0.50.5 mm andand (ii) Waves1.51.5 mm increased. fromincreased. the ENE (ii)(ii) WavesWavesdecreased fromfrom by thethe 8.7% ENEENE to the decreaseddecreased average, byby mainly 8.7%8.7% toto due thethe to averagaverag the decreasee,e, mainlymainly in wave duedue toto heights thethe decreasedecrease below 1 inin m. wavewave (iii) Theheightsheights rest belowbelowof the directions11 m.m. (iii)(iii) TheThe suﬀ restrestered ofof slight thethe directionsdirections variations sufferedsuffered below 2%. slightslight variationsvariations belowbelow 2%.2%.

J.J. Mar. Mar. Sci. Sci. Eng.Eng. 20202020,,8 8,, 240x FOR PEER REVIEW 9 9of of14 14 J. Mar. Sci. Eng. 2020, 8, x FOR PEER REVIEW 9 of 14

Figure 8. (a) Position of the SIMAR Node and currents generated by the mean wave flow. (b) FigureFigureEvolution 8.8. ((a aof)) Position Positionthe percentage of of the the SIMAR ofSIMAR occurrence Node Node and of currentsand each currents of generatedthe study generated bydirections. the meanby the (c wave ) meanEvolution ﬂow. wave (b of) Evolution flow.the mean (b) Evolutionofperiod the percentage of ofeach the ofpercentage of the occurrence study of directions. ofoccurrence each of ( thed )of Evolution studyeach of directions. the of studythe mean (c )directions. Evolution wave height ( ofc) theEvolution meanof each period ofof the the of mean study each periodofdirections. the studyof each directions. of the study (d) Evolutiondirections. of ( thed) Evolution mean wave of heightthe mean of each wave of height the study of each directions. of the study directions.

FigureFigure 9.9.Percentage Percentage of of occurrence occurrence of waveof wave heights. heights. (a) Wave(a) Wave height height between between 0 m and0 m 0.5 and m. 0.5 (b) m. Wave (b) FigureheightWave betweenheight9. Percentage between 0.5 m of and 0.5 occurrence 1.0m and m. (1.0c )of Wave m. wave (c) height Wave heights. betweenheight (a) Wavebetween 1.0 m height and 1.0 1.5 mbetween m.and ( d1.5) Wave0 m. m (dand height) Wave 0.5 greaterm. height (b) Wavethangreater 1.5 height than m. between1.5 m. 0.5 m and 1.0 m. (c) Wave height between 1.0 m and 1.5 m. (d) Wave height greater than 1.5 m. 5. Discussion 5. Discussion 5. DiscussionAmong all the natural environments, the coasts are the ones that most frequently present Among all the natural environments, the coasts are the ones that most frequently present modiﬁcations in their form and disposition due to the action of several factors both natural and modificationsAmong all in the their natural form environments,and disposition the due coasts to the are action the onesof several that mostfactors frequently both natural present and human [38]. The beach changes naturally in the long term due to varying conditions of wind, sea and modificationshuman [38]. The in theirbeach form changes and naturally disposition in the due long to theterm action due to of varying several cond factorsitions both of wind, natural sea and and coastal dynamics or the contribution of sediments [39]. However, short-term human alterations— humancoastal [38]. dynamics The beach or the changes contribu naturallytion of insediments the long term[39]. dueHowever, to varying short-term conditions human of wind, alterations— sea and actions which have become stronger in the last century—must also be considered [40,41]. This is simple coastalactions dynamics which have or thebecome contribu strongertion of in sediments the last century—must [39]. However, also short-term be considered human [40,41]. alterations— This is thanks to the use of cartographic and photographic documents that show the variations of the coast at actionssimple whichthanks have to the become use of strongercartographic in the and last phot century—mustographic documents also be consideredthat show the [40,41]. variations This isof simplethe coast thanks at different to the use dates of cartographicin recent decades. and phot Thographice study period documents can be that di videdshow intothe variationstwo periods: of the coast at different dates in recent decades. The study period can be divided into two periods:

J. Mar. Sci. Eng. 2020, 8, 240 10 of 14 different dates in recent decades. The study period can be divided into two periods: 1956–1992 and 1992–2019. In the first period (1956–1992), the modification of the geomorphology was observed due to the installation of all the groins and jetties, together with the whole development process due to human activity. In the second period (1992–2019), the development of the coast was observed as a consequence of the multiple human actions that could be related to the maintenance of groins and actions, such as sand dumping. Both aspects are discussed below. Regarding the urban expansion, the bay of Cullera has shown the same trend that has been observed in any coastal area, increasing the urban area of the whole municipality from 0.11 km2 in 1956 to 0.78 km2 in 1990, to finally reach 2.32 km2 in 2018 (Figure3). This is in line with what has been observed in the rest of the world, where the coast began to become urbanized in 1990 and around 60% of the world’s population has been concentrated in the first 60 km of coastline [42,43]. On the Valencian coast, the appearance of tourist activities, in general, first affected places close to the sea and fertile agricultural lands [2,44]. In the specific case of Cullera, tourist activities gobbled up the mountain and scrubland area (Figure3). Between 1968 and 1975, the construction of roads began in the mountain area, replacing the contour lines and initiating a process of urbanization that was stopped by the economic crisis in 1976, but continued in the urban development boom of 1998, replacing 0.687 km2 of the mountain with single-family homes. The effects due, in general, to urbanization and anthropization of the environment led to changes in riverbeds and land uses (among others, mountain slopes) that supplied sediments to rivers and gullies that flow into the coast, which has caused a change in the regime and volume of sediments contributed by these routes to the coastal system [2,45]. Just like the mountain area, the agricultural use area has been drastically reduced. Currently, the whole crop areas on the coast have become an urban area, producing an intense and progressive urban occupation, to the point that buildings can be followed almost without interruption along the bay of Cullera [46]. The beach in the study area grew over the entire period from 1956–2019. This growth occurred due to two factors: (i) The construction in the 1970s in the northern zone of breakwaters for what was to be a marina at Cap Blanc, which was never completed, and a groin between Racó beach and Cap Blanc, which caused two phenomena. A large accumulation of sediments in the first 500 m of the beach from the cape toward the south corresponded to a beach with an E-W orientation and a clear retreat over a wide area of almost 1 km until the beach recovered the fundamental coastal direction (see Supplementary File S1). (ii) The construction of groins at the mouth of the Júcar River in the 1950s, with its subsequent expansion in the 1980s, caused a barrier effect of the sediments and generated a strong accretion on the beach to the north of the mouth (Figure4). However, contrary to the beneficial effect that this last work had on the beaches located to the north, it is known that, in many places, the coastal engineering structures built to stabilize the coast generally end up generating short-term erosion effects, as is the case on the beaches to the south of the river mouth [2,11]. The accumulation that has occurred since 1956 on the beach of San Antonio continued until 2000, although in a less significant form and without a major upward trend near the mouth of the Júcar River. This trend has been controlled due to the extraction of sand to feed the area further south in recent years [47]. Finally, analysis of sediment distribution shows that the finest fraction of the sediment was concentrated in the intermediate zone of the bay, while the areas near the mouth of the river concentrated the largest fraction (Figure6b). These observations are consistent with the observations of Cupul-Magaña et al. [48] in the same study area and with the explanations of Griffiths [49]. The sediment distribution was associated with coastal circulation currents that distribute the sediments brought by the Júcar River to the central and northern part of the bay, where the concentration of finer-sized sediments was observed. The waves in the area showed a clear predominance of the directions from the NE to the ESE (Figure8), which generated currents with both N and W components. The N component is explained by the influence of the cape and the W component by the waves themselves, which is consistent with what was observed by the authors of Reference [24]. The influence of the Cape of Cullera caused the waves in the northern area to be directed toward the coast, generating a current toward the south and causing a seaward current toward the middle of San Antonio beach, J. Mar. Sci. Eng. 2020, 8, 240 11 of 14 which coincided with the point in Figure7 where an increase in the size of the sediment can be seen. This is because the finer material was dragged by the waves, leaving the thicker fractions in that area. In the southern zone, due to the groins of the River Júcar, some cells of circular currents were generated that accumulated the material next to the mouth. Furthermore, the high concentrations of silt and clayey material observed in 1987 in front of the mouth of the river were explained by the influence of the discharges of the Júcar River during the rainy season that year, when precipitation reached 700 l/m2 and a maximum river flow of 1100 m3/s [48,50].

6. Conclusions The results presented suggest two issues that deserve to be discussed. On the one hand, the evolutionary trend followed in the coastal sector of the municipality of Cullera with the consideration of the complex natural and human processes that are interacting. On the other hand, the study conducted shows the potential of the combined use of high-resolution satellite images and GIS techniques to monitor the state and dynamics of the coast. Regarding the first question, the whole of the sector studied had a fundamentally cumulative dynamic of sediments. The main cause of the imbalances in the area were the stiffening and channelling of the mouth of the Júcar River, as well as the construction of groins on the beaches of the cape. From that moment on, the sedimentary flow associated with the coastal drift was interrupted, causing a strong accumulation on the beaches located to the north of the river (San Antonio beach) and a growing regression on those located to the south. These processes of interruption of the continental drift, together with the massive tourist urbanization between 1960 and 1970, with the extraction of a traditional sand and road construction, trampling, agriculture, etc., contributed to the physical and ecological degradation of the dune systems. Thus, the vulnerability of these coastal landscapes was disturbed and threatened by the above-mentioned dangers, especially within the last 50 years. Concerning the methodology used in the analysis, the results achieved indicate that digital image processing and GIS are very useful tools for the evolution of coastal changes since they allow the quantification of the areas affected by the different activities undertaken on the coast. Furthermore, it was demonstrated that GIS has great versatility in varying the spatial and temporal scale of the analyses, allowing the manager to select the level of detail required in each analysis, whose potential and precision will depend on the quantity and quality of data. Thus, the creation of a complete, precise and updated database would facilitate the identification of the most effective strategies for sustainable management to avoid the high economic costs derived from the loss of coastal dunes and associated ecological services, even allowing the simulation of scenarios of future changes.

Supplementary Materials: The following are available online at http://www.mdpi.com/2077-1312/8/4/240/s1, Supplementary File S1: Shoreline evolution and transects in Cullera Bay Author Contributions: Conceptualization, J.I.P. and I.L. Methodology, L.B. and J.I.P. Software, L.B. and J.I.P. Validation, L.B. and J.I.P. Formal analysis, L.A. and J.I.P. Investigation, I.L. and J.I.P. Resources, I.L. and J.I.P. Data curation, J.I.P. Writing—original draft preparation, L.A. and J.I.P. Writing—review and editing, L.A., I.L., and J.I.P. Visualization, J.I.P. and I.L. Supervision, L.B. and L.A. Project administration, I.L. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the Generalitat Valenciana through the project GV/2019/017 (Estudio sobre el desgaste y composición de los sedimentos y su influencia en la erosión de las playas de la Comunidad Valenciana). Acknowledgments: We would like to thank the Provincial Services of Coasts from Alicante, Puertos del Estado and the University of Alicante for the information provided. Conflicts of Interest: The authors declare no conflict of interest.

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