Enzo Pranzini

Updrift river mouth migration on cuspate deltas: two examples from the coast of Tuscany (Italy)

The configuration of the Arno and Ombrone deltas (Italy) is evaluated. The terminal courses of the rivers forming these deltas face the dominant wave orthogonal. This configuration came about during rapid delta progradation as a consequence of increased river sediment input due to widespread deforestation within the catchment area, a prevailing phenomenon from the Early Middle Ages to the XVIII century. The rivers attained and maintained their directions as the result of the increased accretion rate on the less exposed downdrift side of the delta. On the more exposed updrift side, delta growth caused the shoreline to gradually rotate so that it directly faced the waves approaching the coast. Here, due to the lower refraction, wave energy per shore unit increased whilst accretion rate decreased. This rotation of the shoreline-induced longshore inversion on the updrift side, whereas today cusp erosion is restoring the original drift direction.

Coastal erosion and protection in Europe

1. Introduction Enzo Pranzini and Allan T. Williams 2. Russia Ruben Kosyan, Marina Krylenko, Daria Ryabchuk and Boris Chubarenko 3. Sweden Magnus Larson and Hans Hanson 4. The Baltic States: Estonia, Latvia and Lithuania Hannes Tonisson, Kaarel Orviku, Janis Lapinskis, Saulius Gulbinskas and Rimas Zaromskis 5. Poland Kazimierz Furmanczyk 6. Denmark Per Sorensen 7. Germany Jurgen Jensen and Klaus Schwarzer 8. Netherlands Frank van der Meulen, Bert van der Valk and Bas Arens 9. Belgium Roger H. Charlier 10. Great Britain (GB) Simon Blott, Robert W. Duck, Michael R. Phillips, Nigel Pontee, Kenneth Pye, and Allan T. Williams 11. Ireland Andrew Cooper 12. France Edward J. Anthony and Francois Sabatier 13. Spain Vicente Gracia, Agustin Sanchez-Arcilla and Giorgio Anfuso 14. Portugal Oscar Ferreira and Ana Matias 15. Italy Enzo Pranzini 16. Eastern Adriatic Kristina Pikelj, Vojislav Dragnic and Nemanja Malovrazic 17. Albania Gjovalin Gruda and Merita Dollma 18. Greece George Alexandrakis, George Ghionis, Serafim E. Poulos and Nikolaos A. Kampanis 19. Bulgaria Margarita Stancheva 20. Romania Adrian Stanica, Nicolae Panin and Glicherie Caraivan 21. Ukraine Yuri N. Goryachkin 22. Conclusions Enzo Pranzini, Lilian Wetzel and Allan Williams.

Aspects of coastal erosion and protection in Europe

The wide variety of physical, political, economic and cultural attributes along European coasts has led to different national management approaches to coastal protection. In all countries, this became problematic when the coast underwent anthropogenic impact and acquired relevant economic value for uses, such as, transport, military, tourism or conservation. However, common ground technology developed according to each country’s political traditions, technical restrictions and economic viability. This paper outlines the major management aspects of coastal erosion and defence in Europe and discusses the large spectrum of shore protection strategies used. It depicts the current coastal defence scene for 25 European countries, and points to the major trends and challenges faced by coastal managers, land owners and users of European coasts, as coastal management embraces both engineering as well as socio-economic aspects.

‘Back to the Beach’: Converting Seawalls into Gravel Beaches

During the 20th century, 5 km of hard structures (seawalls, detached breakwaters and groins) were built along 2.5 km of coast to stabilise the shoreline at Marina di Pisa (Tuscany, Italy). These reflective structures increased nearshore erosion and now a water depth of 7 m deep is found at the offshore toe of the detached breakwaters. Wave reflection pushes sediment flux offshore, inducing downdrift erosion. A project to reduce hard structures, based on their conversion into gravel beaches, is proposed here. The project layout was tested on a 2D physical model and proved to be effective as a coastal protection measure. Furthermore, it is less expensive than the maintenance costs of the present structure and produces a 30 m wide gravel beach, so offering economic benefits because of its recreational value.

Beach Sediment Alteration by Natural Processes and Human Actions: Elba Island, Italy

Abstract The surface characteristics and dimensions of many beaches reflect past inputs of sediment due to human activity in tributary drainage basins. Subsequent control of erosion in drainage basins, changes in flow regimes of streams, and construction of shorefront structures have reduced sediment input and eliminated beach area in many coastal segments, leading to calls for artificial beach nourishment. This study evaluates the compatibility of sediments delivered as a result of human activity in terms of the appearance and utility of beaches by comparing sites on Elba Island, Italy. Beach morphology, mineralogy, grain size, and roundness of sediments were determined for five sites where sediments were introduced by artificial nourishment, by erosion of spoils from iron mines, and by stream flow through agricultural or mining lands. Size, sorting, angularity, and color of sediments determine their acceptability by beach users. These characteristics were determined by evaluating the mineralogy and method of delivery of sediment (rivers, bluff erosion, and artificial replenishment) and subsequent modification by wave and human action. Wave energy and time are critical to the reworking of sediments to achieve more natural characteristics, but these constraints can be overcome by more careful selection of the mineral characteristics of fill sediments, prewashing fill sediments to remove silts and clays to reduce turbidity, grading nourished beaches to cycle sediments into the wave and swash zones to cause better rounding of sediments, or raking the beach to create the sandy backbeach that is favored by beach users.

Canons of Coastal Engineering in the United Kingdom: Seawalls/Groynes, a Century of Change?

ABSTRACT Williams, A.T.; Giardino, A., and Pranzini, E., 2016. Canons of coastal engineering in the United Kingdom: Seawalls/groynes, a century of change? A Royal Commission on Coast Erosion and Afforestation, 1911, investigated the state of coastal erosion and the resulting protection measures carried out in the U.K. This paper looks at progress undertaken with respect to seawall and groyne protection in the more than 100 years since publication of the report. Seawall design has been greatly modified, although curved and stepped designs were built in the Victorian era, as well as the more common vertical ones. Groynes have also been modified from invariably using wood and rock to other materials, e.g., metal, concrete precast elements, geotextiles, as well as shape, e.g., Y, gamma, or T shaped groynes rather than orthogonal to the beach. Numerical/physical modelling has now made both structures much more robust and rigorous, although arguments are still ongoing regarding how they are used. A strong environmental concern and the need to maintain the beach for recreation characterize most present day projects and are factors that were considered but spasmodically a century ago. These factors favoured new solutions from submerged structures to beach nourishment, which limit the leading role of the seawall/groyne structures used 100 years ago.

Reversed responses within a segmented detached breakwater, the Tuscany coast Italy¿a case study

Abstract A multiple detached breakwater system was designed to protect an extended length of shoreline in front of the presidential villa located in the Gombo region, Tuscany, Italy. The purpose of this empirical field study was to examine the impact of the surface-piercing segmented breakwater on the subaqueous morphology and to follow the effect of the breakwaters on the beach. Shoreline mapping was performed on rectified, stereo-plotted air photos and was also based on topographic field surveying. Bathymetric mapping was based on interpolation of profile lines extending to 10 m water depth. Building the breakwaters in a downstream order caused the trapping of the longshore-driven sediments mainly at the southernmost breakwaters that faced the longshore sediment supply. The longshore down-current direction controlled the hierarchy of the beach response. Two relatively coherent behavioral domains were found to exist: (1) the “permanent tombolo stage” of segments 1–3 and (2) the “no sinuosity” response of the beach opposite the northern segment no. 5. The segment no.4, in-between, did not exhibit a coherent behaviour, indicating a drastic reversal in the sedimentary regime. The three southernmost tombolos facing the longshore current became the main sediment trap, causing a lee-side erosional effect to emerge within the protection scheme of the segmented detached breakwaters. The oblique incident waves enter through the gaps and maintain in the inshore the depleted longshore drift, causing the shoreline configuration in the lee of the northern breakwaters to develop into a prograding log-spiral bay.

Recreational Parameters as an Assessment Tool for Beach Quality

ABSTRACT Botero, C., Pereira, C., Anfuso, A., Cervantes, O., Williams, A.T., Pranzini, E., Silva, C.P. 2014. Recreational parameters as an assessment tool for beach In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 556–562 ISSN 0749-0208. Beach quality can be understood according to uses established for this coastal system, the most common being tourism, fishing and conservation. This is especially true with regards to tourism, where quality is frequently measured with respect to two major areas: environmental and recreational. In 2002, an environmental quality index for tourist beaches was developed in Colombia, called ICAPTU (Índice de Calidad Ambiental en Playas Turísticas). ICAPTU had four indicators and eleven parameters, mainly focused in environmental aspects. In 2010, a research project started with the objective of updating ICAPTU with a more comprehensive scope, dividing environmental quality into three indicators: sanitary, eco-systemic and recreational. This research paper presents the progress on the design of five parameters considered in the newer version of ICAPTU, all related to recreational issues: a. Coastal Scenery, focused on an assessment tool tested in Europe, USA and Australia; b. Safety and security, measured from risk perception and real risk; c. Urbanization, related to ecosystem resilience to infrastructure on the shore; d. Zoning, understood as a spatial organization of beach activities; e. Environmental behaviour, assessed from a test focused on common attitudes of tourists when they visit the beach. These five parameters were used on-field techniques as a method for acquiring information. Several instruments were designed based on surveys, checklists and interpretation sheets. Every tool was applied and tested on Colombian beaches located in four Departments: La Guajira, Magdalena, Atlántico and Bolivar. Geospatial technologies are also explored as resources for improving the evaluation of beach environmental quality. Finally, this work concluded that beach quality can be assessed by recreational parameters, scientifically designed, supporting decision making of coastal zone management.

Tracing nearshore bottom currents with sea-bed drifters

Abstract The experience acquired during 36 Woodhead drifter releases performed along the Tuscan coast is briefly reported. Without a costly apparatus, residual current patterns may be easily obtained with this method. Care should be taken, however, when sediment dispersal patterns are required, since weak currents which drag drifters slowly, displace only finer sediments.

Assessing shelf aggregate environmental compatibility and suitability for beach nourishment: a case study for Tuscany (Italy).

Beach nourishment practices are a key aspect in coastal management plans for stakeholders and communities. Stemming from a concrete case-study (Tuscany), this research analyzes: (i) principal problems of current law regulating dredging, (ii) gaps in technical guidelines, (iii) advantages of integrated approaches to the decision-making process, (iv) possible applicable nourishment options and their costs and benefits. Our results show that sand compatibility is driven mainly by grain-size stability due to the occurrence of lower pollution levels in off-shore deposits than in threatened beaches, thus current laws and guidelines should be improved to fill the evident gap in the evaluation process and to include a more complete approach to data evaluation and an integrated approach to ecotoxicity evaluation, which is relevant in cases of geochemical anomalies. The cost-benefit analysis performed indicates that only dredging intended to manage more than 1 million m(3) of aggregates would represent a real advantage for local communities.