Coastal zones are subjected to a wide range of phenomena acting on very different temporal and spatial scales: from decades to days and from hundreds of kilometers to tens of meters. Planning the management of such areas, thus, requires an accurate and updated knowledge of the ongoing processes. While standard monitoring activities are functional for the medium-long time scale and medium-large spatial scale, they struggle to provide adequate information concerning the short period (i.e., days) and small range (i.e., few meters). In addition, such operations are affected by high costs and logistic complexity since they generally involve the deployment of specific aircraft or maritime vehicles. On the contrary, the employment of robotic devices can represent a solution to these issues. Their proper use can allow for frequent surveys and enhance the coverage of the acquired data due to optimized mission strategies. Marine robotics has the potential to arise as an efficient complementary tool to standard monitoring techniques. Nevertheless, the use of marine robots is still limited and should be improved. The purpose of this paper is to discuss the current state of robotic technology, identifying both the benefits and shortcomings of its use for micro-tidal marine-coastal monitoring. The discussion will be supported by actual results, taken as an example, achieved using FeelHippo AUV, the compact Autonomous Underwater Vehicle (AUV) developed by the Department of Industrial Engineering at the University of Florence, Italy.

In this paper the evolution of the Northern Tuscany littoral cell is documented through a detailed analysis of the increasing anthropogenic pressure since the beginning of the 20th century. This sector of the Tuscany coast has been experiencing strong erosion effects that resulted in the loss of large volumes of sandy beaches. The anthropogenic impact on natural processes have been intensified by the construction of two ports in the early decades of the 20th century. Competent authorities reacted by building hard protection structures that tried to fix the position of the shoreline but offset the erosion drive downdrift. Therefore, in the last 20 years a regional Plan was undertaken to gradually replace the hard defense schemes with a softer approach, which involved a massive use of sediment redistribution activities. Many nourishments have been done ever since, using both sand and gravel. All these hard and soft protection operations have been archived in a geodatabase, and visualized in maps that clearly show the progressive change from hard to soft defense. This database may improve the approach to any future analysis of the littoral cell both in terms of research and management, while providing a practical example that may be easily replicated elsewhere.

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.

In the present study we describe a straightforward and highly replicable methodology to assess the anthropogenic sediment budget within a coastal system (the Northern Tuscany littoral cell, Italy), specifically selected in a partially natural and partially highly urbanized coastal area, characterized by erosion and accretion processes. The anthropogenic sediment budget has been here calculated as an algebraic sum of sediment inputs, outputs and transfer (m3) within a 40 year time interval (1980–2020). Sediment management strongly influences the sediment budget and, even if its evaluation is crucial to assess the efficiency of a coastal management policy, it is often difficult to quantify the anthropogenic contribution to sedimentary processes. Different types of intervention are carried out by a variety of competent authorities over time (Municipalities, Marinas, Port Authorities), and the correct accountability of sediment budget is no longer known, or possible, for the scientific community. In the Northern Tuscany littoral cell, sedimentation is concentrated in a convergent zone and updrift of port structures, which have determined a series of actions, from offshore dumping and disposal into confined facilities (sediment output), to bypassing and redistribution interventions (sediment transfer); conversely, river mouths and coastal areas protected by groins and barriers are subjected to severe erosion and coastline retreat, resulting in many beach nourishments (sediment input). The majority of coastal protection interventions were carried out to redistribute sand from one site to another within the study area (2,949,800 m3), while the sediment input (1,011,000 m3) almost matched the sediment output (1,254,900 m3) in the considered time interval. A negative anthropogenic sediment budget (−243,900 m3) is here documented.

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 m3 of aggregates would represent a real advantage for local communities.

A nearshore sediment transport model is developed and presented for the southwest Alabama and Mississippi barrier island coast along the northern Gulf of Mexico, USA. A cellular-type nearshore transport system, supplied by differential sediment sources, characterizes the present day study area, in contrast with previously formulated hypotheses of a net unidirectional, integrated nearshore transport system supplied by a single sediment source. Computer simulations of net longshore sediment transport between Dauphin Island, Alabama, and West Ship Island, Mississippi predict six distinct transport cells characterized by net westward longshore sediment transport. Along eastern Dauphin Island, net longshore transport is eastward toward Mobile Pass. Granulometric trends and changes in the composition of foreshore (step), beach (mid-tide level) and foredune sediments support transport predictions and suggest the possibility of onshore sediment transport along the western flank of the study area. Step and mid-tide sediment grading (coarsening downdrift) is evident along Dauphin Island, and shows a strong relationship with predicted breaker wave height. West of Dauphin Island, sediment samples are characterized by higher concentrations of calcium carbonate (shell) by weight, and heavy minerals, coinciding with a decrease in the inner shelf slope. Field observations and historic shoreline trends are in agreement with longshore sediment transport predictions. For example, chronic shoreline retreat along Dauphin Island, coincides with an increase in net longshore sediment transport, and the highest erosion rate is localized at the net longshore sediment transport reversal (nodal point). Contemporary drift cells appear to experience minimal net sediment exchange because of net longshore transport values approaching zero at most cell termini and ongoing maintenance dredging at the inlets, implying that they function as sediment sinks. Alternative sources of sediment appear to be internal on these barriers.

Severe erosion has been affecting the Ombrone river delta apex since the second half of the 19 th Century and is currently expanding gradually to adjacent beaches. Main causes of this process include coastal marsh reclamation, land-use changes within the watershed, dam construction, and river bed quarrying. In addition, the Ombrone river delta area is subsiding at an average rate of approximately 10 mm/yr. As a result, the river mouth underwent shoreline retreat of over 1100 m in the past 130 years, and the erosion rate currently reaches a peak of 10 m/yr. During recent decades, the Maremma Regional Park decided to allow for beach erosion to proceed, and therefore not to build shore protection structures along the coast. This aimed at keeping the natural landscape unaltered whereas preventing triggering beach erosion on neighboring coastal sectors fed by sediments eroded from the delta apex. However, due to recent acceleration in erosion rates, the shoreline now cuts the coastal dune system and salt water stems interdune swales during storms; as a consequence, valuable junipers, pine forests and freshwater ecosystems have been seriously damaged. In face of that, the Park administration applied for a sustainable shore protection project within the scope of the Regional Coastal Protection Plan, which consisted of managed realignment of 150 m shore extension. The existing, obsolete 420 m long dyke, presently located along the shoreline of the delta southern wing, will be removed and reconstructed 150 m inland as a major protection measure against extreme storm events. From the offshore side of the new seawall a set of 18 groins will be buried into the ground with the crest at -0.50 m; these structures will reach the present shoreline underground; six of them, in the southern sector, will be extended in the nearshore as submerged groins for approximately 150 m. Beach erosion will gradually exhume these structures, which will become progressively more effective in reducing current shoreline retreat rates. Shoreline is forecasted to reach the seawall within 15 to 25 years in such protected conditions. In the meantime the Ombrone River Basin Authority will have to implement efficient measures for restoring river sediment transport at a magnitude capable of allowing natural beach stabilization in the littoral cell. If these parallel actions are developed in the near future, shoreline retreat will be halted before the seawall is reached, resulting in a sandy beach stabilized by the submerged groin set.

Cipriani, L.E., Pranzini, E. Rosas, V. and Wetzel, L. 2011. Landuse changes and erosion of pocket beaches in Elba Island (Tuscany, Italy). Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal symposium), 1774 - 1778. Szczecin, Poland, ISSN 0749-0208. The evolution trend of 17 natural pocket beaches (Elba Island, Italy) under "regular" sediment input was studied over a 24 years (average) preceding a 200 year return time flood. Thirteen beaches were found to be eroding, and only two to be naturally accreting, whereas two increased their surface as a consequence of beach nourishment projects carried in the 1990s. Beach erosion in Elba affects beaches independently from their size and wave energy and appears to be a regional process. Coastal structures are mostly absent from these bays (except for Marina di Campo, where a marina breakwater situated on one headland induced beach rotation). Factors triggering coastal erosion were investigated among land use changes that occurred in the Island after World War II: the development of tourism in Elba Island reduced agricultural activities, increased forest coverage and expanded residential areas. During the past 40 years approximately 3200 hectares of agricultural areas were lost; this corresponds to circa 72% of the original area, diminishing the surface susceptible to soil erosion and thus sedimentary input to the coast.

Follonica Gulf beach is subject to widespread low-rate erosion, which started in the 19th Century due to river diversion for coastal marsh reclamation. Once rivers were re-directed to the coast; land subsidence induced by water extraction sustained erosion. From 1954 to 1984 mean shoreline retreat was approximately 9 m.In the 1960's, development of coastal tourism villages increased beach use and the need for house protection from storms. Detached breakwaters were built, trapping sand from adjacent coastal sectors. This induced shoreline progradation in protected sectors creating a wider beach, but unprotected coastal sectors experienced severe erosion. Stakeholders requested additional protection: the most developed area was gradually protected by detached breakwaters up to complete closure. Comparing the 2005 and 1954 shoreline positions, we see that out of the total length of approximately 21 km of coastline 8 km are accreting; less than 1 km is stable and over 12 km are eroding. Recently, a marina was built on the eastern margin of the study area; however wave diffraction at breakwater tip induced longshore transport and entrance siltation at the cost of western neighbouring beaches.Tourism industry stakeholders, whose economy is based on beach width and quality, were responsible for such coastal degradation, but now cooperate with local and regional administrations, accepting reduction in the use of hard defences - although shoreline realignment will end up penalising someone. Some detached breakwaters have been lowered to 50 cm below mean sea level, whereas others will undergo similar reshaping in the near future. The two oldest sets of coastal defence are now under study, in order to find solutions for a gradual return to more natural conditions. Changes to the marina configuration are being designed to prevent siltation, reaching a new equilibrium for the adjacent beach. We now realise that money spent for shore protection in some sectors would have maintained the 1950's shoreline position along the whole Gulf using beach nourishment, with no landscape deterioration.

The 20-kilometer-long Apuo-versilian beach comprises coastal segments falling under many different administrations: two Regions (Liguria and Tuscany), two Provinces (La Spezia and Massa-Carrara), six Municipalities (Ameglia, Sarzana, Carrara, Massa, Montignoso and Forte dei Marmi), one Interregional River Basin Authority (Magra River) and one Port Authority (Marina di Carrara Port). This stretch of coast is fed by Magra River, empting onto the Ligurian Sea at the northern end of the littoral cell. Due to the reduction of the sediment input from its watershed, the entire coast has been experiencing severe coastal erosion, with shoreline retreat of approximately 800 meters at the river mouth from 1880 until now. Since its construction, which begun in 1920, the Marina di Carrara harbour has been intercepting southwards littoral transport, thus converting the Marina di Carrara historical shoreline retreat: in beach accretion, and therefore increasing erosion down the coast. Several coastal defences have been built south of the harbour since the 1930s and from the river mouth to the south (in Ligurian territory) since the 1960s. These defences were built without a wide scale strategy, and each new structure became a cause for conflicts among different stakeholders as the coast started to be intensively used for tourist and leisure activities. Recently, the different administrations responsible for coastal management started to implement new projects in a more integrated manner, planning at cell scale and considering the management of river sediments to be a fundamental part of Integrated Coastal Zone Management, in light of EUROSION view and recommendations. Information sharing and stakeholder participation was part of this strategy. Beach evolution monitoring was performed and discussed in open meetings and people expectancies and suggestions were carefully considered. This work of reducing conflicts among stakeholders allowed adopting more sustainable coastal defence strategies, aimed at balancing the benefits and reducing the negative fallouts to the neighbouring communities. This paper traces the history of this stretch of coast and analyses the evolution of coastal defence strategies during the last century.