Silva, R.; Martínez, M.L.; Hesp, P.; Catalan, P.; Osorio, A. F.; Martell, R.; Fossati, M.; Miot da Silva, G.; Mariño-Tapia, I.; Pereira, P.; Cienfuegos, R.; Klein, A., and Govaere, G., 2014. Present and future challenges of coastal erosion in Latin America.

The coastal zones of Latin America have many landforms and environments, including sedimentary cliffs, deeply incised estuaries, headlands, barrier coasts and low lying, muddy coastal plains. These forms will respond differently to the expected changes in climate and associated sea level rise, which may produce coastal erosion in the future. Considering the coasts of Latin America overall, erosion is not yet a serious threat, although it is widespread and it is severe in some parts. Major erosion problems are frequently associated with human intervention in sediment supply, with poor planning or with the morphodynamic nature of the coast. Permanent erosional processes, locally or regionally, are caused by tectonic subsidence, deforestation and the fragmentation of coastal ecosystems, land use changes and sediment deficits because of infrastructure built along the coast. In this article we analyse coastal erosion in Latin America and the challenges it presents to the region. We first highlight the relevance of Latin America in terms of its biodiversity; then we describe the population at risk, demographic trends and economic growth throughout the low lying coastal zones. We also examine the vulnerability of the region by analyzing the resilience of key coastal ecosystems after exposure to the most frequent hazards that affect coastal zones in Latin America, namely tropical cyclones, sea level rise, ocean acidification, earthquakes and tsunamis. Finally, we discuss seven case studies of coastal erosion across Latin America. We close the study by pinpointing the main areas of concern in Latin America and explore possible strategies to overcome erosion and thus sustain economic growth, minimize population risk and maintain biodiversity.

Martins, K.A. and Pereira, P.S., 2014. Coastal erosion at Pau Amarelo Beach, northeast of Brazil.

This article concerns the erosion at Pau Amarelo Beach in Pernambuco, Brazil. The maintenance of this beach is important for tourists and the community and is significant for the local economy. Pau Amarelo is a highly urbanized area with poor coastal plain. The coast is characterized by the presence of lined reefs running along the shore. In order to understand the causes of the erosion at this site, coastline variation, the displacement of urban areas and wave characteristics were analyzed. It is believed that both the human incursions on the backshore and the intensification of longshore currents in some parts of the coast, caused by wave diffraction at the reefs, contribute to the beach erosion. The breakwaters built south of Pau Amarelo are also believed to decrease sediment transport by blocking the drift current. Beach nourishment is suggested as the most suitable solution to the erosion at Pau Amarelo.

Mallmann, D.L.B. and Pereira, P.S., 2014. Coastal erosion at Maria Farinha Beach, Pernambuco, Brazil: Possible causes and alternatives for shoreline protection.

The aim of this study is to understand the main processes that are involved in the erosion of Maria Farinha Beach, in Recife, Brazil, a beach of great ecological and socioeconomic importance. Currently, the southern part of the beach is exposed to more frequent periods of erosion, especially during spring tides, while in the northern part accretion can be observed. The possible causes of erosion can be related to: (i) changes in longshore drift rates, resulting in a negative sediment budget; (ii) the impact of the incoming waves, that concentrate energy in a small sector, and/or (iii) urban development on top of the beach system. In order to minimize erosion problems, the following alternatives are suggested: (i) the construction of a submerged breakwater; (ii) the use of a sand bypassing system and (iii) the relocation of existing buildings. It is concluded that the erosion problem at Maria Farinha is complex and difficult to solve, since it has multiple causes.

Gomes, G. and Silva, A.C., 2014. Coastal erosion case at Candeias Beach (NE-Brazil). In: Silva, R., and Strusińska-Correia, A. (eds.).

The present work is a study of changes in longshore sediment circulation due to the presence of a breakwater which interferes with the beach morphology. The study was done using the SMC software (Sistema de Modelado Costero) as the main tool for simulating the coastal dynamics for the different configurations, as well as for determining the wave climate to be applied at the simulations. The beach environment is a complex dynamic system responsive to the impact of waves and currents through a series of changes that can occur at different time scales and the intervention of human constructions. The focus of the present work is the application of SMC to investigate beach erosion in an area of Candeias Beach, in the metropolitan region of Recife (NE-Brazil), after installation and further modification of a hard coastal structure (breakwater), as well as in a scenario without the breakwater at the same area.

Araruna Júnior, J.T.; de Campos, T.M.P., and Pires, P.J.M., 2014. Sediment characteristiscs of an impacted coastal bay: Baía de Guanabara, Rio de Janeiro, Brazil.

Baía de Guanabara is one of the largest and most important bays of the Brazilian coastline. Over recent years coastal erosion problems have been registered there, mainly due to increasing urbanization and industrial development related to the oil and gas industry. This paper presents the results of an experimental program aimed at obtaining the rheological and sedimentation properties of the sediments that are on the pipeline routes in the bay. With this information it is possible to assist the municipality in reducing beach erosion and implementing sustainable measures for better coastal development. It was found that the sediments from Baía de Guanabara have sedimentation rates ranging from 0.63 to 13.25 cm/min. Solid content is relatively low, consistent with the fact that they are unconsolidated sediments. The particle size distribution of the sediments reflects the depth of the water column of Baía de Guanabara; the deeper the water column, the coarser the sediment. However, the sediment shows plasticity, suggesting the presence of organic matter derived from the 20 m³s⁻¹ raw sewage discharged into the bay. Fine sediments are found near shore; these are fluvial in origin or come from diffuse pollution sources. Their activity is high, indicating that it might be correlated to the presence of clay minerals. Regarding physical indices, it was found that the finer sediments have higher water contents and porosities but lower particle densities; total and dry. The coarser sediments present grains of spheroidal format, composed mainly of quartz, feldspar and amethyst.

Alonso, R.; López, G.; Mosquera, R.; Solari, S., and Teixeira, L., 2014. Coastal erosion in Balneario Solís, Uruguay.

Balneario Solís is a seaside resort located in Uruguay, on the northern coast of the outer Río de la Plata estuary. Its main beach has suffered an erosion process that has affected the cliffs, producing a retreat of approximately 35 m between 1980 and 2001. Nowadays, some buildings are at risk of collapse and tourism has been seriously affected. Aerial photo analysis shows a temporal coincidence between the beginning of the erosion process and a change in the growing direction of a sandspit located next to the beach. Assuming the later as a geomorphologic indicator of the net littoral transport, the erosion process was linked to littoral transport change. No human factors were clearly identified to explain this change. Therefore, two hypotheses were formulated and analyzed: climate variability and natural modifications of the bathymetry in the outer zone of the beach. Finally, beach nourishment is proposed in order to restore the beach and protect the cliffs, and some questions are formulated for guiding future works in the site.

Catalán, P.A.; Cienfuegos, R., and Villagrán, M., 2014. Perspectives on the long-term equilibrium of a wave dominated coastal zone affected by tsunamis: The case of Central Chile.

The capability to predict the long term evolution of coastal state parameters can be severely affected by neglecting major geomorphic forcings. Among these, the effect of tsunamis as been largely neglected along the Chilean coast. In this contribution, we present a qualitative and descriptive assessment of the sudden change induced by the tsunami on a coastal location in Central Chile, and the consequent recovery process. The latter is driven mostly by strong wave forcing, with a very fast recovery capactity. The necessity and consequences of including tsunamis in long term evaluations fo coastal morphology are briefly discussed.

Escudero, M.; Silva, R., and Mendoza, E., 2014. Beach erosion driven by natural and human activity at Isla del Carmen Barrier Island, Mexico.

The study site is located on the Gulf of Mexico and is part of the most valuable lagoon-estuarine system in Mexico, not only in ecological terms but also as an important economic and social site for the country. Although the current state of the environment is still reasonably healthy over much of its area, the natural equilibrium has been greatly affected by human activities, as in many of other coastal lagoons worldwide (e.g., infrastructure and building construction, installation of inappropriately designed defense structures, degradation of vegetation and an artificial lagoon opening). The consequence is a sediment deficit that, combined with the impact of tropical cyclones and the absence of an external sand supply, has led to persistent beach erosion. The analysis of the physical settings, historical shoreline changes and hydrodynamic patterns of the study site has helped to identify the critical elements affecting the current state of the beach. This paper proposes a shoreline protection scheme, based on the understanding of the current functioning of the site, in order to reduce local flooding and erosion risks, which affect the population and tourism, and to preserve the natural environmental services of the area.

Odériz, I.; Mendoza, E.; Leo, C.; Santoyo, G.; Silva, R.; Martínez, R.; Grey E., and López, R., 2014. An alternative solution to erosion problems at Punta Bete-Punta Maroma, Quintana Roo, Mexico: Conciliating tourism and nature.

This paper presents an erosion problem found between Punta Bete and Punta Maroma, on the Riviera Maya, Mexico. The case is worth studying as its features are quite complex: ecologically speaking, the area contains part of the Mesoamerican barrier reef, the second largest in the world, an important area of seagrass and large mangrove fields; on the other hand regarding economic aspects, the main activity is tourism, which is of vital importance to the region and nationally. These two opposing interests need to be conciliated in the adoption of a solution to problem of erosion on the coast as both are being degraded at the present. The chronic erosion reported in recent years is due to natural causes, such as the slenderizing of the coral barriers and to anthropogenic causes such as local constructions on the shoreline that interrupt the longitudinal sediment transport. This work describes the characterization of the zone and analyses of marine climate and beach sediment. The hydrodynamics have been numerically modelled with WAPO and COCO models and the morphological response of profiles with the XBeach model. Three possible solutions are proposed and numerically tested, each of which present strengths and weakness. The three alternatives are discussed in order to help decision making as some form of intervention is urgently required.

Lopez, R., 2014. Beach restoration at Grand Velas Hotel, Riviera Maya, Mexico.

Shore erosion is a serious problem that is present in many countries with coastal regions. Mexico is no exception; coasts on the Pacific Ocean, the Gulf of Mexico and the Caribbean Sea suffer from erosion. The pass of seasonal storms and hurricanes and anthropogenic actions on the coasts have played an important role in this matter. These coasts need to be protected to avoid beach retreat and property damage. Knowing how to design suitable coastal protection structures is important to help recover and stabilize a beach. The objective of this study case is to evaluate the performance of a 2008 project designed and built to stabilized and protect 500 m of beach in front of the Grand Velas Hotel Riviera Maya in the state of Quintana Roo. From the observation of what happened on this coast it may be possible to understand erosion protection projects more fully and so, to improve designs in the future.

Martínez, R.; Silva, R., and Mendoza, E., 2014. Identification of coastal erosion causes in Matanchén Bay, San Blas, Nayarit, Mexico.

This work presents an analysis of the erosion processes in Matanchén Bay based on the available historical records; the possible causes were identified and discussed. The bay is located on the Pacific coast of Nayarit state, Mexico; its northern tip is a highly dynamic system that has undergone intense morphological modifications over the last 80 years. At the beginning of the 1940s an unexplained growth in the beach at the northern tip of the bay was observed, while 40 years later, and up to date, erosion processes began adversely affecting small businesses in the area. The primary causes of the erosion are the anthropogenic modifications in the bay and its surroundings, which include the construction of a hydroelectric dam system, new transport infrastructure, tourist facilities, a harbor and several dredging works in the existing port. In this paper the evolution of the coastline at Matanchén Bay and its surroundings is analyzed for the first time and the actual coastline is compared to that predicted under the assumption that no countermeasures against the erosion are adopted.

Vidal-Juárez, T.; Ruiz de Alegría-Arzaburu, A.; Mejía-Trejo, A.; García-Nava, H., and Enriquez, C., 2014. Predicting barrier beach breaching due to extreme water levels at San Quintín, Baja California, México.

This study comprises a first approach to numerically determine the hydrodynamic conditions leading to barrier breaching at San Quintín, located in the northwestern coast of the Baja California peninsula in Mexico. The barrier is backed by a large coastal lagoon, fronted by a field of submerged volcanoes located several kilometers off the coast and is exposed to large incoming wave energy dominated by the Pacific swell. The narrowest barrier beach sections are vulnerable to flooding due to overwash events that take place during concurrent high spring tides, energetic storm waves and a range of storm surge levels. Here, the conditions to barrier overwash and breaching occurrence are identified, and the extent of the floods is numerically quantified. For that purpose, the Delft3D hydrodynamic model is applied coupling waves and flows to simulate a series of scenarios, which comprise storm waves of different magnitudes and periods approaching from typical directions, and coupled to spring tides and several storm surge levels. As a consequence of the presence of submerged volcanoes off the coast, the incoming wave energy is mostly concentrated at two specific locations along the barrier beach, which correspond to the lowest and narrowest barrier locations. Due the large distance between both sites, longshore variations are not expected to be as strong as the cross-shore. Numerical results suggest that the barrier is susceptible to flooding during spring tides combined with extreme waves of significant wave heights larger than 3.5 m and a peak period of 7.5 s, and storm surge levels exceeding 0.9 m, which may lead to breaching.

González-Vázquez, J.A.; Silva, R.; Mendoza, E., and Delgadillo-Calzadilla, M.A., 2014. Towards coastal management of a degraded system: Barra de Navidad, Jalisco, Mexico.

The area known as Barra de Navidad is a barrier lagoon system on the Mexican Pacific. Over the last 40 years the system has undergone serious negative changes in its dynamic processes, mainly due to the anthropogenic activities that have taken place there. The main elements that have damaged the equilibrium of the system are the removal of the distal tip of a sandspit, the dredging of a navigation channel, the construction of a breakwater, the cutting down of large areas of mangrove and the construction of tourist infrastructure on the coastal dunes. These changes have decreased the resilience of the system, thereby increasing its vulnerability. In addition, the lagoon has developed a severe problem of silting and alterations to the hydrodynamic patterns in the system have caused a dramatic retreat of the coastline. The degradation of the system has affected the population and their economic activities to such a degree that a series of hydrodynamic analyses have been carried out to propose a short-term, urgent solution which will be part of a long-term plan that will bring self-sustainable balance to the system.

Delgadillo-Calzadilla, M.A.; Mendoza, E.; Silva, R.; González-Vázquez, J.A., and Infante-Mata, D., 2014. Beach erosion in San Benito Chiapas, Mexico: Assessment and possible solution.

The study area is on the Gulf of Tehuantepec, where a harbour was built at San Benito, near Tapachula, Chiapas, in 1972. Two breakwaters, of 630 m and 800 m, respectively, were constructed to provide protection to the harbour channel. Erosion problems were detected near the harbour even before it was opened to trade. The original design had many flaws as no wave climate analysis had been done and littoral drift had not been taken into account. In 1975, 17 groins were built with the aim of reducing the erosion on the adjacent beach. These were unsuccessful and, in 1980, a rock armour apron was built at the most seriously eroded section in a further attempt to minimize the problem and to protect the population. However, the erosion continues at a rate of around 25 m per year in some sections. Commercial and navigation activities at the harbour are important for the population of San Benito and its surroundings, so coastal management policies must facilitate harmonic coexistence between human activities and the coastal system. This study analyses the problem and offers alternative solutions for minimizing the beach erosion using hard and/or soft solutions.

Nor Aslinda, A.; Wan Hasliza, W.J., and Mohd Radzi, A.H., 2014. Coastal erosion at Tanjong Piai, Johor, Malaysia.

Tanjung Piai, Johor, Malaysia, is a ramsar site, located at the southern-most tip of mainland Asia, and consists mainly of mudflats and mangrove forests. The coast has experienced severe erosion for several decades, in spite of the construction of various coastal defense structures. The reported rates of shoreline retreat were between 2 to 4 m/year. Hydrodynamic modeling using 2008 field data indicate that the maximum current speed observed along the east coast of Tanjung Piai ranges from 0.2 - 0.5 m/s, while the west coast experiences lower current speeds of less than 0.2 m/s. Strong currents occur at the tip of Tanjung Piai with a speed of 0.5 to 0.8 m/s. The simulation also indicates that some local current patterns are formed near the tip due to the presence of a small island as the flow entering the study area during flooding were reflected to the east while the flow during the ebb tide tend to move toward the opposite direction. Wave simulations show that most of the waves come from Singapore and the Straits of Malacca, with amplitudes of over 1.5 m, are reduced to less than 0.8 m as they travel towards Tanjong Piai coast. These local hydrodynamic conditions, combined with the existence of regular ship wakes, are believed to be the reason for the intensive erosion at Tanjung Piai. Model simulations incorporating the proposed coastal protection measures indicated positive and negative impacts of the hydrodynamic changes around the study area. The results shown that the magnitude of the current speed and wave height would be reduced in the area behind the structures but slightly increased on the other parts of the coast. These changes will determine the sediment transport movement in the area. Therefore, it is necessary to understand the hydrodynamic characteristics before implementing any kind of coastal protection measures because they may protect some area from erosion, but may not be favourable to the other parts of the coast.

Strusińska-Correia, A., 2014. Beach stabilization at Kołobrzeg, Poland.

The coastal erosion on the Baltic Sea at Kołobrzeg (Poland) is a result of the superposition of the local hydrodynamics and the anthropogenic factors of this multi-functional, intensively developing city. Particularly high rates of erosion are observed along the 3 km-long shore, east of the port, despite countermeasures undertaken (groynes, seawalls, waveblocks and beach nourishment). In view of the increasing importance of Kołobrzeg as a tourist resort and the investment boom taking place in the immediate vicinity of the shoreline, the preservation of the disappearing beaches and protection of the low-lying urbanized areas became a burning issue for the local authorities. However, the means of coastal protection applied have been ineffective and have also impaired the natural beauty of the beach. The continuous submerged breakwater of length of almost 3 km, constructed in 2010 - 2012, seems to have stabilized the beach, although its impact on the adjacent coastal sections and environment requires further analysis. In this paper, the causes of the coastal erosion at Kołobrzeg are discussed, based on the morpho-geological and hydrodynamic conditions as well as the character of the urban development. The beach protection used is analyzed chronologically in terms of its effectiveness and novelty.