Research

Open AccessArticle

An Index-Based Method to Assess the Resilience of Urban Areas to Coastal Flooding: The Case of Attica, Greece

by

Charalampos Nikolaos Roukounis

,

Vasiliki K. Tsoukala

and

Vassilios A. Tsihrintzis

J. Mar. Sci. Eng. 2023, 11(9), 1776; https://doi.org/10.3390/jmse11091776 - 11 Sep 2023

Viewed by 352

Abstract

The aim of this study is to assess the resilience of coastal urban areas and their exposure to sea-level rise and coastal flooding, using the proposed Coastal Resilience Index (CResI). The CResI is an innovative combination of diverse characteristics. It includes 19 parameters [...] Read more.

The aim of this study is to assess the resilience of coastal urban areas and their exposure to sea-level rise and coastal flooding, using the proposed Coastal Resilience Index (CResI). The CResI is an innovative combination of diverse characteristics. It includes 19 parameters and is implemented using GIS techniques. The parameters included in the CResI are classified into six category factors (geomorphology, flooding, wave exposition, land use, socioeconomic, and infrastructure/functional). The Analytic Hierarchy Process is used to assign weights and rank the parameters. The framework is tested in the southwest waterfront of the Athens Metropolitan Area in Greece. The study identified that around 25% of the coastal area could be at risk of coastal flooding in the upcoming years, including areas in both the metropolitan and suburban environments. As a result, the need for adaptation measures cannot be overlooked. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Impact of Spatial Segmentation on the Assessment of Coastal Vulnerability—Insights and Practical Recommendations

by

Christina N. Tsaimou

,

Andreas Papadimitriou

,

Vasiliki Ι. Chalastani

,

Panagiotis Sartampakos

,

Michalis Chondros

and

Vasiliki K. Tsoukala

J. Mar. Sci. Eng. 2023, 11(9), 1675; https://doi.org/10.3390/jmse11091675 - 25 Aug 2023

Viewed by 337

Abstract

Coastal areas are dynamic multidimensional systems challenged by the complex interactions between natural, environmental, and human-induced pressures, as well as the ever-changing climate. A comprehensive evaluation of their spatial and temporal features enables the development of effective practices required to apply integrated coastal [...] Read more.

Coastal areas are dynamic multidimensional systems challenged by the complex interactions between natural, environmental, and human-induced pressures, as well as the ever-changing climate. A comprehensive evaluation of their spatial and temporal features enables the development of effective practices required to apply integrated coastal zone management (ICZM) policies. ICZM seeks to address the vulnerability of coastal areas in an attempt to mitigate their weaknesses and increase their resilience. Hence, coastal vulnerability assessment is a prerequisite to proceed with optimal adaptation or upgrading actions. Currently, assessments are performed by considering different approaches related to dividing coastal areas into segments to observe the spatial variations of vulnerability. The present research seeks to investigate the impact of the spatial segmentation of coastal areas on the assessment of their vulnerability. To achieve this, a case study of the coastal zone of the Municipality of Thebes, located in the Northeastern Corinthian Gulf, Greece, is examined. Five segmentation approaches are applied in terms of a physical-based vulnerability assessment for two different time horizons, (a) the present and (b) the future, by incorporating the climate change impacts. This study allows for optimizing practices to estimate vulnerability parameters and obtain reliable results for practical applications while reducing time-consuming analyses. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Projected Sea Bottom Temperature Variability in the East China Shelf Seas by 2100

by

,

,

and

J. Mar. Sci. Eng. 2023, 11(6), 1192; https://doi.org/10.3390/jmse11061192 - 08 Jun 2023

Viewed by 536

Abstract

Existing research has proven the increase in sea surface temperature (SST) due to global warming. However, the sea bottom temperature (SBT) may exhibit different characteristics in various regional seas. The East China Shelf Seas (ECSSs), which are important shelf seas in the Western [...] Read more.

Existing research has proven the increase in sea surface temperature (SST) due to global warming. However, the sea bottom temperature (SBT) may exhibit different characteristics in various regional seas. The East China Shelf Seas (ECSSs), which are important shelf seas in the Western Pacific, hold ecological significance when analyzing their SBT variations in a warming future. This article investigates both the interannual and interdecadal SBT variations from 2006 to 2100, utilizing the projection results from phase 5 of the Climate Model Intercomparison Project (CMIP5) sponsored by the Intergovernmental Panel on Climate Change (IPCC). We conducted an analysis of the interdecadal variation by comparing the SBTs from the 2030s, 2060s, and 2090s to the SBT observed in the 2010s. Our findings reveal a significant increase in SBT in the ECSSs. By 2100, the region is projected to experience enhanced warming of 1.18 °C. The springtime warming intensity of the Bohai Sea, reaching 1.92 °C, can be twice the rate of global ocean warming. The outer shelf of the ECSSs also exhibits significant increases in SBT. Through an analysis of the correlation between SBT and ocean currents, we investigate the potential mechanisms behind these observations. This paper provides insights into future SBT variations from both an interannual and interdecadal perspective, explaining the causes and the projected increase in environmental stresses on the benthic ecosystem over the next eighty years. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Graphical abstract

Open AccessArticle

Computing Vegetation Indices from the Satellite Images Using GRASS GIS Scripts for Monitoring Mangrove Forests in the Coastal Landscapes of Niger Delta, Nigeria

by

Polina Lemenkova

and

Olivier Debeir

J. Mar. Sci. Eng. 2023, 11(4), 871; https://doi.org/10.3390/jmse11040871 - 20 Apr 2023

Cited by 2 | Viewed by 1441

Abstract

This paper addresses the issue of the satellite image processing using GRASS GIS in the mangrove forests of the Niger River Delta, southern Nigeria. The estuary of the Niger River Delta in the Gulf of Guinea is an essential hotspot of biodiversity on [...] Read more.

This paper addresses the issue of the satellite image processing using GRASS GIS in the mangrove forests of the Niger River Delta, southern Nigeria. The estuary of the Niger River Delta in the Gulf of Guinea is an essential hotspot of biodiversity on the western coast of Africa. At the same time, climate issues and anthropogenic factors affect vulnerable coastal ecosystems and result in the rapid decline of mangrove habitats. This motivates monitoring of the vegetation patterns using advanced cartographic methods and data analysis. As a response to this need, this study aimed to calculate and map several vegetation indices (VI) using scripts as advanced programming methods integrated in geospatial studies. The data include four Landsat 8-9 OLI/TIRS images covering the western segment of the Niger River Delta in the Bight of Benin for 2013, 2015, 2021, and 2022. The techniques included the ’i.vi’, ’i.landsat.toar’ and other modules of the GRASS GIS. Based on the GRASS GIS ’i.vi’ module, ten VI were computed and mapped for the western segment of the Niger River Delta estuary: Atmospherically Resistant Vegetation Index (ARVI), Green Atmospherically Resistant Vegetation Index (GARI), Green Vegetation Index (GVI), Difference Vegetation Index (DVI), Perpendicular Vegetation Index (PVI), Global Environmental Monitoring Index (GEMI), Normalized Difference Water Index (NDWI), Second Modified Soil Adjusted Vegetation Index (MSAVI2), Infrared Percentage Vegetation Index (IPVI), and Enhanced Vegetation Index (EVI). The results showed variations in the vegetation patterns in mangrove habitats situated in the Niger River Delta over the last decade as well as the increase in urban areas (Onitsha, Sapele, Warri and Benin City) and settlements in the Delta State due to urbanization. The advanced techniques of the GRASS GIS of satellite image processing and analysis enabled us to identify and visualize changes in vegetation patterns. The technical excellence of the GRASS GIS in image processing and analysis was demonstrated in the scripts used in this study. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Application of Idealised Modelling and Data Analysis for Assessing the Compounding Effects of Sea Level Rise and Altered Riverine Inflows on Estuarine Tidal Dynamics

by

,

,

,

and

J. Mar. Sci. Eng. 2023, 11(4), 815; https://doi.org/10.3390/jmse11040815 - 11 Apr 2023

Cited by 1 | Viewed by 1158

Abstract

Estuaries worldwide are experiencing increasing threats from climate change, particularly from the compounding effects of sea level rise (SLR) and varying magnitude of river inflows. Understanding the tidal response of estuaries to these effects can guide future management and help assess ecological concerns. [...] Read more.

Estuaries worldwide are experiencing increasing threats from climate change, particularly from the compounding effects of sea level rise (SLR) and varying magnitude of river inflows. Understanding the tidal response of estuaries to these effects can guide future management and help assess ecological concerns. However, there is limited existing understanding on how estuarine tidal dynamics may respond to the compounding effects of SLR and altered riverine inflows in different estuaries. To partially address this knowledge gap, this study used data analysis and scrutinised idealised hydrodynamic models of different estuary shapes and boundary conditions to (i) identify broad effects of SLR on estuarine tidal dynamics under various river inflow conditions, (ii) determine how longitudinal cross-sections are impacted by these effects, and (iii) highlight some implications for environmental risk management. Results indicated that short- to moderate-length, high convergent estuaries experience the greatest and short- to moderate-length prismatic and low convergent estuaries experience the least variations in their overall tidal dynamics (i.e., tidal range, current velocity, and asymmetry). These variations were most evident in estuaries with large riverine inflows and macrotidal conditions. Compounding effects of SLR and altered riverine inflows induced spatially heterogenous changes to tidal range, current velocity, and asymmetry, with transects nearest to the estuary mouth/head and at a three-quarter estuary length (measured from estuary mouth) identified as the most and the least vulnerable zones, respectively. These findings provide an initial broad assessment of some effects of climate change in estuaries and may help to prioritise future investigations. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Coastal Erosion Identification and Monitoring in the Patras Gulf (Greece) Using Multi-Discipline Approaches

by

Nikolaos Depountis

,

Dionysios Apostolopoulos

,

Vasileios Boumpoulis

,

Dimitris Christodoulou

,

Athanassios Dimas

,

Elias Fakiris

,

Georgios Leftheriotis

,

Alexandros Menegatos

,

Konstantinos Nikolakopoulos

,

George Papatheodorou

and

Nikolaos Sabatakakis

J. Mar. Sci. Eng. 2023, 11(3), 654; https://doi.org/10.3390/jmse11030654 - 20 Mar 2023

Cited by 4 | Viewed by 1518

Abstract

The primary objective of this research is to demonstrate advanced surveying methods and techniques for coastal erosion identification and monitoring in a densely human-populated coastline, the southern coastline of the Gulf of Patras (Greece), which diachronically suffers erosion problems expected to become worse [...] Read more.

The primary objective of this research is to demonstrate advanced surveying methods and techniques for coastal erosion identification and monitoring in a densely human-populated coastline, the southern coastline of the Gulf of Patras (Greece), which diachronically suffers erosion problems expected to become worse in the forthcoming years due to climate change and human intervention. Its importance lies in the fact that it presents a robust methodology on how all modern scientific knowledge and techniques should be used in coastal erosion problems. The presented methods include the use of satellite and aerial photo imaging, shallow seabed bathymetry and morphology, sediment sampling, geotechnical investigations, as well as hydrodynamic modelling. The results are extensively analyzed in terms of their importance in coastal erosion studies and are cross-validated to define those areas most vulnerable to erosion. Towards this scope, the seabed erosion rate produced by hydrodynamic modelling is compared with the coastal vulnerability index (CVI) calculations performed in the examined area to identify which coastal zones are under a regime of intensive erosion. The results between the CVI and the seabed erosion rate appear to coincide in terms of the erosion potential, especially in zones where the vulnerability regime has been calculated as being high or very high, with the P. oceanica meadows playing an important role in reducing erosion. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium

by

Iason A. Chalmoukis

,

Georgios A. Leftheriotis

and

Athanassios A. Dimas

J. Mar. Sci. Eng. 2023, 11(3), 519; https://doi.org/10.3390/jmse11030519 - 27 Feb 2023

Viewed by 734

Abstract

Erosion and flooding are the main threats for most coastal regions. Nature-based solutions, such as coastal vegetation (CV) fields, have received significant attention in recent years because they effectively dissipate wave energy while maintaining biodiversity. In this study, a porous medium model was [...] Read more.

Erosion and flooding are the main threats for most coastal regions. Nature-based solutions, such as coastal vegetation (CV) fields, have received significant attention in recent years because they effectively dissipate wave energy while maintaining biodiversity. In this study, a porous medium model was implemented in an in-house software to simulate the three-dimensional, two-phase (water/air) flow induced by wave propagation past CV fields. First, the model was validated against experimental measurements of wave propagation past a CV field on a horizontal bed. Then, the model was used to assess the influence on wave behaviour of the equivalent porosity, n_eq, and the cross-shore length, L_CV, of a CV field with a constant plant height on a beach with a constant bed slope. Results were obtained for the non-vegetated case (n_eq = 1) and five vegetated cases with different n_eq and L_CV values. It was found that decreasing n_eq moves wave breaking offshore at larger depths (40% increase for the case with n_eq = 0.82), while it does not affect much the breaking height (4% was the largest difference). For very high n_eq (0.98 in the present study) and/or small L_CV (83% of the wavelength just offshore of the CV field in the present study), wave breaking may occur at depths smaller than in the non-vegetated situation due to increased wave shoaling over the corresponding CV fields. The undertow distribution is strongly modified and an increased wave setup (highest for n_eq = 0.82) is observed for all vegetated cases in comparison to the non-vegetated one. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Open AccessArticle

Accelerating Predictions of Morphological Bed Evolution by Combining Numerical Modelling and Artificial Neural Networks

by

Andreas Papadimitriou

,

Michalis Chondros

,

Anastasios Metallinos

and

Vasiliki Tsoukala

J. Mar. Sci. Eng. 2022, 10(11), 1621; https://doi.org/10.3390/jmse10111621 - 02 Nov 2022

Cited by 1 | Viewed by 1002

Abstract

Process-based models have been employed extensively in the last decades for the prediction of coastal bed evolution in the medium term (1–5 years), under the combined action of waves and currents, due to their ability to resolve the dominant coastal processes. Despite their [...] Read more.

Process-based models have been employed extensively in the last decades for the prediction of coastal bed evolution in the medium term (1–5 years), under the combined action of waves and currents, due to their ability to resolve the dominant coastal processes. Despite their widespread application, they are associated with high demand for computational resources, rendering the annual prediction of the coastal bed evolution a tedious task. To combat this, wave input reduction methods are generally employed to reduce the sheer amount of sea-states to be simulated to assess the bed level changes. The purpose of this research is to further expand on the concept of input reduction methods by presenting a methodology combining numerical modelling and an Artificial Neural Network (ANN). The trained ANN is tasked with eliminating wave records unable to initiate sediment motion and hence further reduce the required computational times. The methodology was implemented in both an idealized and a real-field case study to examine the sensitivity, and produced very satisfactory predictions of the rates of bed level change, with respect to a benchmark simulation containing a very detailed wave climate. The obtained results have strong implications for further accelerating the demanding morphological simulations while enhancing the reliability and accuracy of model predictions. Full article

(This article belongs to the Special Issue Estuaries, Coasts and Seas in a Changing Climate)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Special Issue "Estuaries, Coasts and Seas in a Changing Climate"

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI