Reducing sea cliffs hazards in pocket beaches through beach nourishment on the Barlavento Coast (Algarve, Portugal)

Tourism based on “sun and beach” is the main economic activity in the Algarve region. A considerable part of the beaches of the Barlavento coast corresponds to embedded sand accumulated along the irregular lacework-like coastline of rocky cliffs cut into Miocene calcarenites. The pattern of touristic occupation in the Algarve and the geodynamics of the rocky sea cliffs, characterized by discontinuous and intermittent occurrence of slope mass movements, result in a high level of risk to beach users along pocket beaches. In order to mitigate the risk associated with the cliff geodynamics, artificial beach nourishment was performed in Castelo and Coelha pocket beaches on the Barlavento Coast, in 2014, increasing the beach area by 3.5 times. The effects of the beach nourishment on the occupation patterns of those beaches along the 2006-2016 decade, before and after the beach nourishment, are herein presented and discussed. Occupancy data were obtained covering different seasons along the year, by counting the number of beach users, regardless of age, using periodic and systematic photographs taken at strategic points that provide full coverage of the beach areas. Before the beach nourishments the area of dry sand outside high and moderate hazard zones, measured at half-tide under average summer wave conditions was 500 m2 at Coelha beach and 800 m2 at Castelo beach. After beach nourishment the same area increased to 6700 m2 at Coelha beach and 7100 m2 at Castelo beach. Results show that, following the beach fill, beach occupation by recreational users naturally shifted seaward, moving out from the cliff hazard areas. After the intervention, the occupation of high and moderate hazard areas reduced significantly, from 37 % to 11 % in Castelo beach and from 59 % to 27 % in Coelha beach. Keywords: beach nourishment; hazard; rocky cliffs; Algarve; Portugal.

Error on the Estimation of Sand Size Parameters When Using Small Diameter Sieves and a Solution

Analyses were carried out to determine the main sand size parameters (median grain size D50 and sorting σ) for beach nourishment purposes using the sieving method aboard a dredger. Due to a lack of space and the need to carry and use the material with ease, the sieves are commonly small (10 cm diameter), and the shaking procedure is usually performed by hand. However, the influence of shaking, either mechanically or manually, has not yet been studied with 10 cm diameter sieves. Therefore, 20 samples were taken from inside the hopper of a trailing suction dredger and sieved both manually and mechanically for 10 min. The results showed that manual sieving yielded higher D50 values than the mechanical procedure. The average error arising from using the manual method was 14%, but it can reach 36.5%. The granulometric analysis carried out for different shaking times has shown that this error is < 5% when at least 20 min of shaking is performed. The mechanical procedure gave always finer sand results. In addition, the overfill ratio calculated for both mechanical and manual results reached differences of up to 48%.

Evolution of Sediment Parameters after a Beach Nourishment

A methodology for monitoring the behaviour and size of sand after a beach nourishment process is presented herein. Four sampling campaigns (before and just after the nourishment, after six months and one year later) were performed on four beaches of the Gulf of Cadiz (Spain). D50 and sorting size parameters were analysed. Among the results, it should be noted that differences of up to 20% between native and nourished sand values disappear only one year after the nourishment.

Does Sand Beach Nourishment Enhance the Dispersion of Non-Indigenous Species?—The Case of the Common Moon Crab, Matuta victor (Fabricius, 1781), in the Southeastern Mediterranean

Sand beach nourishment (BN) is one of the commonest “soft solutions” for shore protection and restoration. Yet it may have ecological consequences. Can this practice enhance the introduction and dispersal of non-indigenous species (NIS)? There has been little research on the impacts of nourishment on NIS, especially in the southeastern Mediterranean, a region considered most affected by invading biota. However, so far only one study referred to the possible interaction between BN and the success of invading species. It reports increasing numbers and densities of the aggressive, omnivorous Indo-Pacific moon crab, Matuta victor (Fabricius, 1781) in Haifa Bay (northern Israel) between 2011 and 2017. This research suggests a possible role of anthropogenic disturbance in the outbreak of M. victor and blames the Israel Ministry of Environmental Protection for authorizing a (rather small scale) BN in Haifa Bay in 2011 as an alleged cause for this outbreak. Circumstantial indirect evidence is not sufficient to establish the role of nourishment in promoting the establishment and dispersal of NIS. There are plenty of examples of successful settlement and rapid and large-scale distribution of NIS (including another member of the genus Matuta), especially in the eastern Mediterranean, without any BN in the region. Furthermore, the location where the M. victor specimens were sampled was exposed to more prevailing and frequent anthropogenic marine stressors than BN, such as eutrophication, pollution, fishing activities and particularly port construction. To firmly establish an assumed role of nourishment in the invasion of NIS, assessments must be based on solid and orderly planned scientific research to be designed well before the beginning of any BN. It is suggested that direct communication between environmental regulators and scientists is crucial for improving both scientific research and environmental management policies.

The economic value of beach nourishment in South Carolina

Tourism has become increasingly important in South Carolina’s economy, particularly beach tourism that accounts for two-thirds of tourist spending. Maintaining beaches is a requirement for a successful beach tourism industry. In the past 30 years, about 1.7 million yd3 of sand has been placed annually on South Carolina beaches. The annual cost has been $20.2 million in 2019 dollars or $13.9 million (2019 dollars) if federal mitigation and emergency sand placements are not included because their purpose was not in support of tourism. Beach nourishment has been very successful in combating shoreline recession. From 1984-1987 through 2006, South Carolina shorelines that were not nourished receded 101 ft on average, and shorelines that were nourished advanced 110 ft on average — and tourism boomed. South Carolina beach tourists generate $16.6 billion annually in South Carolina economic development and about $1.8 billion in taxes. For each $1 spent on beach nourishment, South Carolina receives over $1,200 in economic development generated by beach tourists and federal, state, and local governments receive almost $130 in taxes. Beach tourists have options, and with the state government spending only $3.1 million annually on beach nourishment versus the Florida state government spending $50 million on Florida beaches, South Carolina must be careful to maintain its beaches to continue attracting tourists at record levels.

Assessment of and Adaptation to Beach Erosion in Islands: An Integrated Approach

Island beaches, which form significant natural and economic resources, are under increasing erosion risk due to sea level rise. The present contribution proposes an integrated methodological framework for the evaluation of the socio-economic significance of beaches and their vulnerability to sea level rise and the design of effective adaptation measures. The approach comprises four steps: (i) beach ranking on the basis of their socio-economic significance and vulnerability in order to prioritize adaptation responses; (ii) monitoring of the hydro- and morphodynamic regime of the most highly ranking beaches using field observations and modelling, (iii) assessment of the sediment volumes required for beach nourishment under different scenarios of sea level rise and nourishment designs; (iv) evaluation of the marine aggregate potential of the adjacent areas that can be used for beach nourishment. The framework was applied to the Greek island of Chios, which has many beaches that are already under erosion. The methodology was shown to provide a structured approach for the assessment and response to erosion of the most vulnerable beach.

Evolution of Marine Bars under Micro and Mesotidal Settings of Mahanadi Delta Coast

Shoreward migration process of longshore bar is an important aspect of shoreline changes in the Mahanadi delta front. It involves coalescence of individual bars to form large complex bars just before welding on to the shoreline. Such welding sometimes results in the formation of large hook spits. Bar welding mechanism can be an extremely important form of natural beach nourishment. This study aims to detect stages of evolution of longshore bars and consequent welding with mainland. Multi-dated Landsat images have been used to detect evolution of longshore bar and welding processes. QGIS platform has been used to process images and compose required maps.