Beach nourishment — the addition of sand to increase the width or sand volume of the beach — is a widespread coastal management technique to counteract coastal erosion. Globally, rising sea levels, storms and diminishing sand supplies threaten beaches and the recreational, ecosystem, groundwater and flood protection services they provide. Consequently, beach nourishment practices have evolved from focusing on maximizing the time sand stays on the beach to also encompassing human safety and water recreation, groundwater dynamics and ecosystem impacts. In this Perspective, we present a multidisciplinary overview of beach nourishment, discussing physical aspects of beach nourishment alongside ecological and socio-economic impacts. The future of beach nourishment practices will vary depending on local vulnerability, sand availability, financial resources, government regulations and efficiencies, and societal perceptions of environmental risk, recreational uses, ecological conservation and social justice. We recommend co-located, multidisciplinary research studies on the combined impacts of nourishments, and explorations of various designs to guide these globally diverse nourishment practices. Beach nourishment is a well-established engineering practice to slow erosion and maintain or expand sandy beaches, but sea level rise, diminishing sand resources and recreational, groundwater and ecological concerns require new assessments and designs of this coastal management technique. This Perspective describes the multidisciplinary aims and impacts of sandy beach nourishment.

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Beach nourishment has complex implications for the future of sandy shores

Shoreline changes and its impact on the mangrove ecosystems of some islands of Indian Sundarbans, North-East coast of India

This paper shows coastal evolution along the Andalusia Region (Spain) and the impacts on it of coastal structures. The study area was divided into 47 units to calculate the erosion/accretion/stability (or evolution) rates by using the DSAS extension of ArcGIS software. Evolution rates were divided into different classes from “Very high accretion” to “Very high erosion”. As a result, 9 units recorded accretion, 19 stability and 19 erosion. Further, 17 units presented a positive balance and 28 units a negative one, showing a negative net balance of 29,738.4 m2/year corresponding to the loss of 1784.30 km2 of beach surface in the 1956–2016 period. The distribution of evolution areas along the studied coast was carried out by means of the “R” project for statistical computing. The analysis evidenced the impact of rigid structures: accretion was essentially observed up-drift of ports and groins and in correspondence of protection structures, especially of breakwaters. Erosion classes were observed down-drift 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. Last, results were used to determine the distribution of swash- and drift-aligned coastal sectors and main direction of sedimentary transport.

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The Mediterranean Coast of Andalusia (Spain): Medium-Term Evolution and Impacts of Coastal Structures

Beach nourishment along the Mediterranean coast of Israel represents a new approach to mitigate coastal erosion by adding suitable sand to threatened beaches. This ‘soft’ solution has become more environmentally and economically acceptable than traditional ‘hard’ solutions, such as seawalls, revetments, detached breakwaters and groins. Beach nourishment projects have been implemented on the Israeli coast north of Ashdod Port (2011), north of Ashkelon Marina (2015) and in the south of Haifa Bay (2016–2017). The performance of these projects was analyzed and compared with nourishment projects along the Mediterranean beaches of Italy, France and Spain. Despite a lack of detailed documentation on most of the European nourishment projects, they proved more durable than the Israeli projects, which were compromised when the imported sand eventually washed offshore. Key factor for the Israeli projects’ failure include the unsuitable morphology of the beaches; insufficient unit sand volume (m3/m—volume of nourished sand per meter of the beach length); and imported sand that was too fine versus native sand. The unique physical conditions of the Israeli coast specifically, its open shelf and straight coastline subject to relatively high waves with a very long fetch—also contributed to the poor durability of the nourishment. To improve durability on future projects: imported grain size should be at least 1.5–2.0 times the native sand; unit sand volume should be 400–500 m3/m; and supporting measures should be utilized as appropriate.

https://www.mdpi.com/2077-1312/8/4/273/pdf

Sand Beach Nourishment: Experience from the Mediterranean Coast of Israel

Sea, Sun, and Sand (3S) are relevant and determining elements for choosing a tourist destination in Ecuador, a country with about 1200 km of coast along the Pacific Ocean. This study analyzed the market potential of the 3S in 64 beaches, 10 located in the Galapagos and 54 in the continental zone (of Ecuador). The methodology used was exploratory and bibliographical, complemented by a descriptive analysis. The color of the water was assessed by direct observation, sand samples were taken to a laboratory for color analysis, and information on the hours of light was obtained from international archive data. The data obtained were compared with other world famous 3S tourism destinations. The Galapagos had the best results, with attractive white sand beaches, sea blue water color, and an elevated sunshine time; meanwhile, the continental zone presented poor beaches with dark sand and unattractive water color. To strengthen 3S tourism, managers should work on the enhancement of complementary aspects such as culture, gastronomy, and architecture, promoting the creation of new coastal tourist routes and destinations.

https://www.mdpi.com/2071-1050/12/8/3468/pdf

An Attempt to Characterize the "3S" (Sea, Sun, and Sand) Parameters: Application to the Galapagos Islands and Continental Ecuadorian Beaches

Analysis of a large shoreline database (from 1878 to 2017) and recompilation of information on type/age of shore protection structures along the Northern Tuscany, allowed a deep insight of the progressive armouring of this coastal sector. The area experienced beach erosion since the end of the 19th century due to reduced sediment inputs from rivers and harbour constructions. Shore protection structures started to develop at the beginning of the 20th century, first to protect settlements and coastal roads, later to maintain a beach for tourist activity. The changing of the goal and the increasing awareness of the negative impact of some structures resulted in an evolution of coastal defence projects: initially, seawalls and revetments, later detached breakwaters and, more recently, groins. Today, a reduction in hard structures is perceived by removing or lowering detached breakwaters and groins below mean sea level. The forcing function of the growing tourism industry is producing a demand for projects and their design is detailed in this paper: results will be of use in the correct design of a long-term, general, erosion management plan to restore the natural sediment circulation patterns.

Shore Protection Structures Increase and Evolution on the Northern Tuscany Coast (Italy): Influence of Tourism Industry

This paper presents the results of a study carried out to support the Region of Tuscany Coastal Sediment Management Plan, with the main aim of establishing the sediment budget considering the time span from 1981–1985 to 2005 for the 56 coastal sectors into which the 215 km-long continental sandy coast of Tuscany (Italy) was divided. The sand stability (according to a stability index) and colour compatibility (according to the CIEL*a*b* colour space with an acceptability range conforming to national guidelines) were determined in order to assess the possibility of using the available sediment in accreting sectors to nourish the beach in eroding areas. Only in two cases—i.e., the updrift of a harbour (at Viareggio) and in a convergence zone (at Marina di Pietrasanta)—are the volumes of sufficient magnitude to support a large nourishment project; however, the mean sand size is too small to guarantee efficient nourishment, even with medium-term stability. In contrast, the colour difference, in most of the cases, was shown to be acceptable. Other small sediment stocks, suitable for colour but not for grain size, can be used for periodic ephemeral nourishment works to support seasonal tourist activities. The limited resources available make it necessary to adopt a plan for their optimal use from a regional perspective. This kind of study is of great interest for the proposal of sound management actions to counteract the increasing erosion processes linked to climate change phenomena and human effects on rivers and coastal systems.

https://www.mdpi.com/2077-1312/8/1/33/pdf

An Integrated Coastal Sediment Management Plan: The Example of the Tuscany Region (Italy)

The main aim of this paper is to analyze the development of the railway network in Sicily (Italy), where it runs close to the sea on two of the three sides of the island, and give an overview of the related impacts on coastal environment and tourism. In order to achieve such an objective, the impacts of the railway network were analyzed according to coastal typology (distinguishing between rocky and sandy coastal sectors) and distance from the shoreline (dividing distance values in concrete intervals). Rails were mostly emplaced in flat coastal areas due to the island’s rugged terrain: out of 1592 km of railway, ca. 350 km is located less than 1000 m from the shoreline (123 km on rocky sectors and 227 km on beaches and coastal plains). On sandy beaches and low sandy coastal sectors, approximately 6 km of track is within 25 m from the shoreline, a value rising to 16 km if a 50 m distance is considered, 48 km at 100 m and 103 km at 200 m distance. In correspondence of rocky platforms and high cliffed sectors, data reported for short distances between the rail and the shore are similar to ones observed along sandy coastal sectors, but differ when distance increases, i.e., there is only 32 and 47 km of railway respectively within 100 and 200 m from the shoreline. The emplacement of the railway embankment on beaches and dunes favored coastal squeeze and enhanced coastal erosion due to wave reflection on the embankment, which had to be protected by hard structures. Impacts on rocky sectors, with respect to beach and dune systems, are generally low because such sectors are usually stable (they do not need to be protected), less attractive to tourists and present small urban development. Tourism was affected by reducing landscape quality, beach access and width. More detailed studies and monitoring programs are necessary to locally assess the detailed impacts of the railway network, with this study constituting a preliminary but useful approximation to determine which coastal sectors are potentially the most affected. Results obtained in this paper can stimulate similar researches in other countries to prevent or decrease railway impacts on “Sun, Sea and Sand” tourism and, in general, on the coastal environment.

https://www.mdpi.com/2071-1050/13/13/7068/pdf

An overview on railway impacts on coastal environment and beach tourism in Sicily (Italy)

Sand colour can give important information about mineral composition and, consequently, sediment source areas and input systems. Beach appearance, which is mostly linked to sand colour, has a relevant economic function in tourist areas. In this paper, the colour of 66 sand samples, collected along both natural and nourished beaches in the western Mediterranean coast of Spain, were assessed in CIEL*a*b* 1976 colour space. The obtained results showed relevant differences between natural and artificially nourished beaches. The colour of many nourished beaches generally differs from the native one because the origin of the injected sand is different. The native sand colour coordinates’ range is: L* (40.16–63.71); a* (−1.47–6.40); b* (7.48–18.06). On the contrary, for nourished beaches’ the colour range is: L* (47.66–70.75); a*(0.72‒5.16); b* (5.82–18.82). Impacts of beach nourishment on the native sand colour were studied at San Juan beach, the most popular one along the study area. Nourishment works were performed after severe erosion, usually linked to anthropic activities/structures and storm events, but also to increase beach width and hence benefit tourism.

The Origin of Sand and Its Colour on the South-Eastern Coast of Spain: Implications for Erosion Management

This paper presents the history and evolution of the different projects carried out from 1999 to 2008 at Cavo beach in the Elba Island, Italy. The village of Cavo almost completely lost its beach in the 1970s due to the reduction of sedimentary input, and the backing coastal road was defended by a revetment and two detached breakwaters. Such severe erosion processes continued in the following years and impeded any possibility of beach tourist development. In 1999, a project based on the removal of existing breakwaters and beach nourishment works based on the use of gravel as borrow sediment and the construction of two short groins to maintain nourished sediment, raised environmental concern and did not find the approval of the stakeholders. They were worried about the characteristics of the sediments, i.e., waste materials from iron mining rich in red silt and clay. Such sediment fractions made the sea red during the nourishment and deposited on the Posidonia oceanica meadow in front of the beach, with a potential environmental impact. Furthermore, they cemented the gravel fraction forming a beach rock. Between 2006 and 2008, these materials were covered with better quality gravel, extending and raising the beach profile, which required the elevation and lengthening of the two existing groins. Beach evolution monitoring following the second project, based on morphological and sedimentological data acquired before, during and after the works, demonstrated the great stability of the newly created beach. The wider beach has allowed the construction of a promenade and the positioning, in summer, of small structures useful for seaside tourism, increasing the appeal of this village. Data presented in this paper shows an interesting study case, since few examples exist in international literature regarding gravel nourishment projects monitoring and evolution.

Irene Cinelli

Papers

Shore Protection Structures Increase and Evolution on the Northern Tuscany Coast (Italy): Influence of Tourism Industry

An Integrated Coastal Sediment Management Plan: The Example of the Tuscany Region (Italy)

An overview on railway impacts on coastal environment and beach tourism in Sicily (Italy)

The Origin of Sand and Its Colour on the South-Eastern Coast of Spain: Implications for Erosion Management

The Making of a Gravel Beach (Cavo, Elba Island, Italy)