40 research outputs found
European marine aggregates resources: Origins, usage, prospecting and dredging techniques
Marine aggregates (sand and gravel) are important mineral resources and traded commodities. Their significance is bound to increase further, due to increasing coastal zone development, stricter environmental regulation concerning land-won aggregates and increasing demand for beach replenishment material. Marine aggregate (MA) deposits can be differentiated into relict and modern deposits. The former consist of sedimentary material deposited in the past and under different environmental and sedimentary regimes than those existing presently (e.g. the gravel/ sand deposits of the Pleistocene buried river valleys of the northwestern European shelves). The latter are deposits, which have been formed and controlled by the modern hydro-and sediment dynamic conditions (e.g. the linear sand banks of the southern North Sea). The present contribution reviews the current state of affairs in 9 representative European Member States concerning the prospecting and extraction (dredging) techniques as well as the levels of production and usage. The review has shown a mixed record as, in some of the studied States, marine aggregate production is an important and streamlined activity, whereas other States have not yet developed efficient marine aggregate policies and industries. It has also shown that although attempts have been lately made to coordinate the field, the industry still faces problems, which hinder its sustainable development. These include (amongst others): lack of standardisation of the relevant information, difficulties in the access to information, non-coherent regulatory regimes and limited collaboration/coordination between the marine scientific research establishments and the marine aggregate industry. These issues should be addressed as quickly as possible in order to exploit effectively this important mineral resource
Climate change impacts on critical international transportation assets of Caribbean Small Island Developing States (SIDS): the case of Jamaica and Saint Lucia
This contribution presents an assessment of the potential vulnerabilities to climate variability and change (CV & C) of the critical transportation infrastructure of Caribbean Small Island Developing States (SIDS). It focuses on potential operational disruptions and coastal inundation forced by CV & C on four coastal international airports and four seaports in Jamaica and Saint Lucia which are critical facilitators of international connectivity and socioeconomic development. Impact assessments have been carried out under climatic conditions forced by a 1.5 °C specific warming level (SWL) above pre-industrial levels, as well as for different emission scenarios and time periods in the twenty-first century. Disruptions and increasing costs due to, e.g., more frequent exceedance of high temperature thresholds that could impede transport operations are predicted, even under the 1.5 °C SWL, advocated by the Alliance of Small Island States (AOSIS) and reflected as an aspirational goal in the Paris Climate Agreement. Dynamic modeling of the coastal inundation under different return periods of projected extreme sea levels (ESLs) indicates that the examined airports and seaports will face increasing coastal inundation during the century. Inundation is projected for the airport runways of some of the examined international airports and most of the seaports, even from the 100-year extreme sea level under 1.5 °C SWL. In the absence of effective technical adaptation measures, both operational disruptions and coastal inundation are projected to increasingly affect all examined assets over the course of the century
AUTOMATED 2-D SHORELINE DETECTION FROM COASTAL VIDEO IMAGERY: AN EXAMPLE FROM THE ISLAND OF CRETE
Beaches are both sensitive and critical coastal system components as
they: (i) are vulnerable to coastal erosion (due to e.g. wave regime
changes and the short-and long-term sea level rise) and (ii) form
valuable ecosystems and economic resources. In order to
identify/understand the current and future beach morphodynamics,
effective monitoring of the beach spatial characteristics (e.g. the
shoreline position) at adequate spatio-temporal resolutions is required.
In this contribution we present the results of a new, fully-automated
detection method of the (2-D) shoreline positions using high resolution
video imaging from a Greek island beach (Ammoudara, Crete). A
fully-automated feature detection method was developed/used to monitor
the shoreline position in geo-rectified coastal imagery obtained through
a video system set to collect 10 min videos every daylight hour with a
sampling rate of 5 Hz, from which snapshot, time-averaged (TIMEX) and
variance images (SIGMA) were generated. The developed coastal feature
detector is based on a very fast algorithm using a localised kernel that
progressively grows along the SIGMA or TIMEX digital image, following
the maximum backscatter intensity along the feature of interest; the
detector results were found to compare very well with those obtained
from a semi-automated ‘manual’ shoreline detection procedure. The
automated procedure was tested on video imagery obtained from the
eastern part of Ammoudara beach in two 5-day periods, a low wave energy
period (6-10 April 2014) and a high wave energy period (1 -5 November
2014). The results showed that, during the high wave energy event, there
have been much higher levels of shoreline variance which, however,
appeared to be similarly unevenly distributed along the shoreline as
that related to the low wave energy event, Shoreline variance ‘hot
spots’ were found to be related to the presence/architecture of an
offshore submerged shallow beachrock reef, found at a distance of 50-80
m from the shoreline. Hydrodynamic observations during the high wave
energy period showed (a) that there is very significant wave energy
attenuation by the offshore reef and (b) the generation of significant
longshore and rip flows. The study results suggest that the developed
methodology can provide a fast, powerful and efficient beach monitoring
tool, particularly if combined with pertinent hydrodynamic observations
Analytical Research Infrastructures in Europe - A key resource for the five Horizon Europe missions
Contains fulltext :
228237.pdf (publisher's version ) (Open Access)41 p
Assessment of island beach erosion due to sea level rise: the case of the Aegean archipelago (Eastern Mediterranean)
The present contribution constitutes the first
comprehensive attempt to (a) record the spatial characteristics of the
beaches of the Aegean archipelago (Greece), a critical resource for both the
local and national economy, and (b) provide a rapid assessment of the
impacts of the long-term and episodic sea level rise (SLR) under different
scenarios. Spatial information and other attributes (e.g., presence of
coastal protection works and backshore development) of the beaches of the 58
largest islands of the archipelago were obtained on the basis of
remote-sensed images available on the web. Ranges of SLR-induced beach
retreats under different morphological, sedimentological and hydrodynamic
forcing, and SLR scenarios were estimated using suitable ensembles of
cross-shore (1-D) morphodynamic models. These ranges, combined with
empirically derived estimations of wave run-up induced flooding, were then
compared with the recorded maximum beach widths to provide ranges of
retreat/erosion and flooding at the archipelago scale. The spatial
information shows that the Aegean pocket beaches may be particularly
vulnerable to mean sea level rise (MSLR) and episodic SLRs due to (i) their narrow widths
(about 59 % of the beaches have maximum widths < 20 m), (ii) their limited terrestrial sediment supply, (iii) the substantial coastal
development and (iv) the limited existing coastal protection. Modeling
results indeed project severe impacts under mean and episodic SLRs, which by
2100 could be devastating. For example, under MSLR of 0.5 m – representative concentration pathway (RCP)
4.5 of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on
Climate change (IPCC)
– a storm-induced sea level rise of 0.6 m is projected to result in a complete
erosion of between 31 and 88 % of all beaches (29–87 % of beaches
are currently fronting coastal infrastructure and assets), at least temporarily.
Our results suggest a very considerable risk which will require significant
effort, financial resources and policies/regulation in order to
protect/maintain the critical economic resource of the Aegean archipelago