Coastal Boulder Dynamics Inferred from Multi-Temporal Satellite Imagery, Geological and Meteorological Investigations in Southern Apulia, Italy

Marco Delle Rose,Luca Orlanducci,Paolo Martano

doi:10.3390/w13172426

Marco Delle Rose, Luca Orlanducci + Show 1 more

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https://doi.org/10.3390/w13172426

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Abstract

Boulder dynamics may provide essential data for coastal evolution and hazards assessment and can be focused as a proxy for the onshore effect of intense storm waves. In this work, detailed observations of currently available satellite imagery of the Earth surface allowed us to identify several coastal boulders displacements in the Southern Apulia coast (Italy) for a period between July 2018 and June 2020. Field surveys confirmed the displacements of several dozens of boulders up to several meters in size, and allowed us to identify the initial position for many of them. Two possible causative storms were identified analysing archive weather maps, and calculations based on analytical equations were found in agreement with the displacement by storm waves for most of the observed boulders. The results help to provide insights about the onshore effect of storm waves on the coastal hydrodynamics and the possible future flooding hazard in the studied coast.

Highlights

Boulder dynamics is an issue of growing concern in Earth Sciences since it may provide essential data for coastal evolution and hazards assessment [1,2,3,4,5]
The results found a global agreement between the boulder transport distance, as detected by satellite imagery and field geological surveys, and the characteristic wave heights of the strongest identified storms, giving support to use the displaced boulders as proxies for the coastal flooding hazard
With reference to the two positions occupied by the boulders in July 2018 and June 2020, respectively, it is obviously not possible to establish whether the position changes were caused by one or more displacements

Summary

Introduction

Boulder dynamics is an issue of growing concern in Earth Sciences since it may provide essential data for coastal evolution and hazards assessment [1,2,3,4,5]. Geomorphological monitoring is the primary tool to study the coastal morphodynamic processes, and boulder transport [6,7]. The identification of displaced boulders can be followed by on site surveys on the selected places. While careful geological and geomorphological investigations are mandatory to improve our sedimentological and morphodynamic knowledge [18,19,20], basic geometrical, physical, and kinematic features of boulders displaced during high energy events give a measure of the wave impact on the coast [21,22,23]

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