Impressive abrasion rates of marked pebbles on a coarse-clastic beach within a 13-month timespan

Abstract

In this paper the abrasion rate on a coarse-clastic beach was evaluated by calculating the volume loss recorded on indigenous pebbles within a 13-month timespan. The experiment was carried out at Marina di Pisa (Italy) on an artificial beach that was built to counteract the erosion processes affecting this sector of the coast. A total of 240 marble pebbles (120 rounded and 120 angular) were marked using the RFID technology and injected on the beach. The volume loss measured after consecutive recovery campaigns was progressively increasing, reaching the maximum value after 13 months (61% overall). The average volume loss is consistent between rounded and angular pebbles at any time (59.3% and 64.2% after 13 months respectively), meaning that the roundness is not a primary control factor on abrasion rate. The pebbles that did not reach such abrasion rates after 8 and 10 months (volume loss less than 20%) were found at heights equal or greater than 2 m above mean sea level, on the crest of the storm berm that formed during the strongest storms. This implies that the highest wearing is achieved in the lower portion of the backshore, which is also the area that underwent major topographic modifications. Here, sea water action might also exert chemical influence on the pebbles, adding to the mechanical abrasion. The main result of this research, indicating an impressive volume loss on beach pebbles in a short timespan, could be of key importance for coastal managers. The optimization of coarse sediment beach nourishments is also relevant, taking into right consideration that the volume loss due to sediment abrasion might exceed 50% of the original fill volume just after 1 year in the most dynamic portion of the beach

Short term displacements of marked pebbles in the swash zone: Focus on particle shape and size

“…Gravel is not only larger, but usually varies over several orders of magnitude greater than beach sands (Buscombe and Masselink, 2006) and this characteristic creates extremely evident texture variations on coarse clastic beach surfaces, which cyclically raises the interest of researchers. After the early papers written mainly around the 1970s and 1980s (Bluck, 1967;Carr, 1969Carr, , 1971McLean and Kirk, 1969;Carr et al, 1970;McLean, 1970;Gleason and Hardcastle, 1973;Orford, 1975;Kirk, 1980;Caldwell, 1981;Williams and Caldwell, 1988;Isla, 1993;Isla and Bujalesky, 1993), a renewed interest in sediment transport based on different coarse particle characteristics formed during the first decade of this millennium (Buscombe and Masselink, 2006;Ciavola and Castiglione, 2009;Bluck, 2011;Bertoni et al, 2012a). Textural mosaics of different clast shapes and sizes are common and different cross-shore sizeshape zonations and modes of transport were demonstrated by many authors (Bluck, 1967(Bluck, , 2011Orford, 1975;Williams and Caldwell, 1988;Isla, 1993;Ciavola and Castiglione, 2009;Hayes et al, 2010), although the relative importance of size and shape in sorting sediment is yet to be resolved (Buscombe and Masselink, 2006).…”

Measuring pebble abrasion on a mixed sand and gravel beach using abrasion baskets

“…Dornbusch et al (2002Dornbusch et al ( , 2003 have investigated the influence of wave conditions on abrasion, finding that abrasion rates are linked to mean wave height. Bertoni et al (2011Bertoni et al ( , 2012 explained the difference in abrasion rates of pebbles released on the lower swash zone (4.2%) and those pebbles on the upper swash zone (1.6%) as a function of differences in wave exposure. Thus, the influence of wave conditions on abrasion has been recognized but the link has been tentative.…”

“…However such time spans are unlikely to be achieved as sediment or research projects would not last so long. The advantage of RFID technology is that in addition to the study of the transport of coarse particles on the beach Bertoni et al, 2009Bertoni et al, , 2010Miller et al, 2011;Osborne et al, 2011), tracing allows abrasion loss of beach sediment grains to be measured (Allan et al, 2006;Bertoni et al, 2011Bertoni et al, , 2012Dickson et al, 2011). Allan et al (2006) returned 200 tagged cobbles onto a MSG beach in Oregon, USA.…”

“…The average abrasion loss of relocated cobbles on days 64 and 207 were reported to be 0.4% and 1.8%, respectively. Bertoni et al (2011Bertoni et al ( , 2012 released 200 marble pebbles with transponders on two renourished pebble beaches at Marina di Pisa. Over a period of two months, a total of 81 pebbles were relocated and reweighed.…”

A Wireless Sensor Network Framework for Real-Time Monitoring of Height and Volume Variations on Sandy Beaches and Dunes

“…After attempts made by painting gravel particles [21], using allochthonous lithologies [22], and coupling pebbles to electronic devices [23], the technology that produced better results in terms of recovery rate was the Radio Frequency IDentification (RFID). Individual pebbles would be unequivocally identified by a passive transponder activated by the low frequency radio signals transmitted by an antenna [24,25]. Though useful for many purposes, this method does not provide any clue about the trajectories the tracers underwent between the recoveries.…”