4 research outputs found
The Role of Sea State to the Morphological Changes of Prasonisi Tombolo, Rhodes Island, Greece
Wave-induced morphodynamic processes that cause formation, preservation, and destruction of the Prasonisi tombolo in Rhodes Island are investigated, based on satellite image analysis and numerical modeling. A new method is developed for extracting wave events that consist of successive wave data of similar characteristics. The wave events refer either to wind seas or swell seas. This process combined with the satellite image analysis is then utilized for the derivation of the most representative wave scenarios that affect tombolo and salient formation. In particular, the main factors that play a significant role in tombolo and salient evolution are the offshore wave conditions, the location and width of the surf zone, the maximum value of the wave breaking index in the study area, and the initial bottom bathymetry before the study area is exposed to a new sea state. In general, the proposed method provides a realistic insight into tombolo morphodynamics and can be used to provide a cost-effective approach and a wave data-reduction technique for coastal engineering studies
Assessment of the physical impact of a short-term dredging operation on a semi-enclosed environment: South Euboean Gulf, Greece
The potential influence of short-period (May-June 2012) dredging
activities (for the installation of a submarine gas pipeline) on
physical properties of the marine environment of two shallow-water sites
in the Aliveri and Varnavas areas of South Euboean Gulf (Greece) has
been evaluated. During the dredging operation in Varnavas, the induced
dredge plume traveled up to 750 m from the shoreline, featured by light
attenuation coefficient (c(p)) maxima of 4.01-4.61 m(-1) and suspended
particulate matter (SPM) concentrations up to 6.01 mg L-1. After
dredging the previous parameters reduced to the ambient seawater
condition, 0.45 m(-1) and < 2.8 mg L-1 on average, respectively.
Likewise in Aliveri, the dredging-associated sediment plume drifted
offshore up to 400 m from the shoreline, characterized by c(p) maxima of
2.11-4.86 m(-1) and SPM concentrations up to 13.07 mg L-1. After the
completion of the excavation and trenching activities, the c(p) and SPM
values were restored to the pre-disturbance condition, 0.6 m(-1) and <
2.2 mg L-1 on average, respectively. The migration of the dredge plume
in both dredging sites was accomplished through the formation of
intermediate and benthic nepheloid layers, whose development and
evolution were governed by seawater stratification and flow regime. The
dredging-derived SPM levels appeared to increase within a distance of no
more than 300 m from the shoreline (near-field zone). Based on data from
the literature, this SPM enhancement together with the deposition of a
post-dredging residual mud veneer in the near-field zone could
deteriorate local marine biota, but in a reversible way
Assessment of the Coastal Vulnerability to the Ongoing Sea Level Rise for the Exquisite Rhodes Island (SE Aegean Sea, Greece)
The foreseeable acceleration of global sea level rise could potentially
pose a major threat to the natural charm and functional integrity of the
world-renowned tourist coastal attractions of Rhodes Island, as a result
of the anticipated increasing frequency of flooding and erosion events.
Hence, this study aims to determine the most vulnerable segments (in
terms of physical impact) of the Rhodes coastline through the widely
accepted coastal vulnerability index (CVI), applying a combination of
well-known, broadly used approaches and methods. The frequency
distribution of the current CVI along the island’s coastline suggests a
rather worrying high to very high vulnerability of 40%. In addition, a
CVI projection to the end of the 21st century (based on the
Intergovernmental Panel on Climate Change predictive scenarios)
indicates an enhancement of the total vulnerability by 48%, mainly
focused on the majority of the western coastline. Hence, a considerable
number of popular coastal destinations in the island shall remain under
unignorable threat and, therefore, coastal managers and decision-makers
need to hatch an integrated plan to minimize economic and natural
losses, private property damage and tourism infrastructure deterioration
from flooding and erosion episodes, which will most likely be
intensified in the future