Anthropogenic Impact on Beach Heterogeneity within a Littoral Cell (Northern Tuscany, Italy)

Abstract

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 All these hard and soft protection operations have been archived in a geodatabase, and visualized in maps that clearly show the progressive change from hard to soft defense.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.

Integrating Different Databases to Offer a Geological Perspective of Coastal Management: A Review Case from the Northern Tuscany Littoral Cell (Italy)

“…Conversely, accretion areas were located at Marina di Pietrasanta, which is a convergence zone of the littoral drifts coming from the Magra River and the Arno River, and updrift of the Port of Viareggio, where sediment coming from the eroding beaches' downdrift tends to accumulate. Another convergence zone was reported in the southernmost sector of the littoral cell, approximately at Tirrenia (Figure 2); here, the drift coming from the Arno River meets that coming from the south, whose origin is not fully understood yet [42]. The evidence of drift directions is also supported by the compositional analysis of the sediments constituting the beach.…”

“…The present morphodynamic conditions of the northern Tuscany littoral cell have strongly been affected by the development of human activities since 1850. After centuries of consistent accretion along the shore, the last century has been characterized by profound modification in the balance between input and output, which ultimately has led to erosion effects at many sites along the cell [42]. Such variation was mainly determined by…”

“…The present morphodynamic conditions of the northern Tuscany littoral cell have strongly been affected by the development of human activities since 1850. After centuries of consistent accretion along the shore, the last century has been characterized by profound 5 of 17 modification in the balance between input and output, which ultimately has led to erosion effects at many sites along the cell [42]. Such variation was mainly determined by increasing human pressure on coastal settlements, both longshore (e.g., intense urbanization and the proliferation of hard structures) and in the river basin (e.g., riverbed dredging, dam construction, and river mouth armoring); all these factors have contributed to decreasing the sediment input of any local streams to the sea, which has translated to an extensive coastal retreat.…”

“…Sediment accumulated longshore, resulting in a huge accretion of the delta lobes, which continued up to midway through the 19th century. Presently, erosion processes are still active at different sites along the littoral cell [42,44,45]. The most intense effects were documented in the northernmost sector between the Magra River mouth and Cinquale and at the Arno River, either north or south of the mouth (Figure 2).…”

Multi-Decadal Deltaic Land-Surface Changes: Gauging the Vulnerability of a Selection of Mediterranean and Black Sea River Deltas

“…The impact of shoreline engineering structures is clearly displayed by differential shoreline erosion and accretion. The high L→W levels of the Arno (89%) and the Ombrone (71%) also indicate significant rates of shoreline erosion on a coast beleaguered by problems of a fluctuating river sediment supply [30] and a fragmented longshore drift system characterized by several cells created by engineering structures to stave off erosion [31,32]. This is a pattern of disrupted sediment connectivity, involving both the river-to-coast continuum and increasingly engineered shorelines, that repeats itself throughout the Mediterranean [33].…”