Morphological cells in the Ragusa littoral (Sicily, Italy)

Geomorphologic information, topographic maps (dated 1967), aerial photographs (dated 1999 and 2008), and spatial analysis procedures were used to investigate a 90 km long coastal sector in South Sicily (Italy). Information was obtained on coastal erosion/accretion areas, general sediment circulation pattern and littoral cell distribution. Human-made structures and natural headlands constituted important artificial limits dividing littoral in morphological cells. Ports and harbours were observed at Scoglitti, Punta Secca, Marina di Ragusa, Donnalucata and Pozzallo. Most of them worked as “transit” limits which interrupted predominant, eastward directed sedimentary transport, this way generating accretion in updrift (west) side of mentioned structures and erosion in downdrift (east) side. During the 1967–2008 period, about 62,000 m2 and 42,000 m2 of beach surface were respectively formed updrift of Scoglitti and Donnalucata ports. The construction of Pozzallo port gave rise to the formation of a “convergent” limit which favoured large accretion (94,000 m2) east of port structure. Most important natural structures were observed at Punta Zafaglione, P. Braccetto and Cava d’Aliga. The knowledge of littoral cell distribution acquires a great importance for appropriate management of coastal erosion processes which may be mitigated installing by-passing systems in ports and harbours and carrying out nourishment works in eroding areas, often located downdrift of ports and harbours (when these structures work as transit limits) and in central part of littoral cells (when these structures work as convergent limits)

Error determination in the photogrammetric assessment of shoreline changes

The evaluation of error or uncertainty in shoreline change studies is an issue of prime importance for providing an adequate framework for calculated rates of change and to allow the establishment of threshold values above which the rates would be significant. In this note, a practical, easy-to-use method is presented to estimate error involved in the calculation of shoreline changes on aerial photographs, including the three most used types of shoreline indicators: high water line, dune/cliff toe and cliff top. This approach takes into account the specific characteristics of each shoreline proxy, such as relief in the case of the cliff top or tidal oscillations in the case of the high water line. At the same time it includes the error components that are independent from the proxy, basically related to the technical aspects of the process such as photo scanning and georeferencing. A practical example of application of the method is provided for several types of data inputs, based on shoreline changes around the Bay of Cádiz (SW Spain)

Late Quaternary beach deposits and archaeological relicts on the coasts of Cyprus, and the possible implications of sea-level changes and tectonics on the early populations

<p>Late Pleistocene beach deposits in 22 selected sites around Cyprus demonstrate the vertical changes in the Earth's crust in that island over the last 125 ka. The beach/shallow-marine deposits were observed on the abraded coastal cliffs at 3–22 m above the present sea-level. They overlie Pliocene marls, and some of them contain the Senegalese marine gastropods <em>Persististrombus latus</em>, <em>Bursa granularis</em> and <em>Conus ermineus</em> that no longer live in the Mediterranean. These are index fossils for the Marine Isotope Stage (MIS) 5e in the Mediterranean and, as such, suggest an uplift of up to 15.5 m over about the last 125 ka: that is a maximal rate of 0.12 mm a⁻¹. These findings are in accordance with Holocene beachrocks, abrasion platforms, wave notches and Roman/Byzantine fish tanks that retained their elevations, and thus enable the reconstruction of the coast encountered by the early colonizers. While the maximal uplift since the early Holocene has been minor and did not exceed 1.2–1.5 m, the sea-level changes have reached 40–50 m. The transition between the impermeable Pliocene marls and the porous Late Pleistocene deposits above them is the origin of freshwater springs and associated vegetation. The early colonizers seemed to recognize the potential of that essential permanent source of water and excavated wells, the earliest wells known so far. The locations of the Early Neolithic settlements (Mylouthkia and Akanthou) adjacent to visible water springs along the coastal cliffs may not be incidental. Not surprisingly, recent wells dug in the coastal Pleistocene deposits rely on the very same hydrological setting. </p