The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Christopher Koutitas - One of the best experts on this subject based on the ideXlab platform.

  • The impact of watershed management on Coastal Morphology: A case study using an integrated approach and numerical modeling
    Geomorphology, 2014
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Abstract Coastal Morphology evolves as the combined result of both natural- and human- induced factors that cover a wide range of spatial and temporal scales of effect. Areas in the vicinity of natural stream mouths are of special interest, as the direct connection with the upstream watershed extends the search for drivers of morphological evolution from the Coastal area to the inland as well. Although the impact of changes in watersheds on the Coastal sediment budget is well established, references that study concurrently the two fields and the quantification of their connection are scarce. In the present work, the impact of land-use changes in a watershed on Coastal erosion is studied for a selected site in North Greece. Applications are based on an integrated approach to quantify the impact of watershed management on Coastal Morphology through numerical modeling. The watershed model SWAT and a shoreline evolution model developed by the authors (PELNCON-M) are used, evaluating with the latter the performance of the three longshore sediment transport rate formulae included in the model formulation. Results document the impact of crop abandonment on Coastal erosion (agricultural land decrease from 23.3% to 5.1% is accompanied by the retreat of ~ 35 m in the vicinity of the stream mouth) and show the effect of sediment transport formula selection on the evolution of Coastal Morphology. Analysis denotes the relative importance of the parameters involved in the dynamics of watershed–coast systems, and – through the detailed description of a case study – is deemed to provide useful insights for researchers and policy-makers involved in their study.

  • An integrated approach to quantify the impact of watershed management on Coastal Morphology
    Ocean & Coastal Management, 2012
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Abstract Coastal areas are subject to various natural- and human-induced impacts affecting water quality and Morphology evolution. Regarding the latter, its correlation with watershed processes is self-evident, as natural streams in many cases constitute the largest sediment source for the Coastal environment. However, literature references that study concurrently both fields (i.e. terrestrial and Coastal) and their quantitative correlation are scarce. The present paper introduces and describes in detail an integrated approach to quantify the impact of watershed management on Coastal Morphology using numerical modeling. The core of the proposed methodology refers to a coupled-calibration approach of the watershed and the Coastal models, incorporating three scenarios of data availability regarding the parameters of interest (Coastal Morphology, overland sediment transport and Coastal sediment transport). To support the applicability of this approach, a brief presentation of its successful application for an area in North Greece is also presented. The study retains the viewpoint of Integrated Coastal Zone Management, and is deemed to provide an operational tool for future researchers and policy planners.

  • Modelling the impact on Coastal Morphology of the water management in transboundary river basins
    Management of Environmental Quality: An International Journal, 2008
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Purpose – To study the impact of River Nestos (North Greece) dams construction on Coastal Morphology.Design/methodology/approach – In order to study the evolution of the Coastal Morphology in the area, an “one‐line shoreline change model” was developed (PELNCON). The model's input comprises the field characteristics, the wave characteristics at the breaker line and a “source” term for the sediment supply rate by River Nestos. The model calculates the shoreline change over a given period of time. The annually transported sediment quantity by the river is estimated using filed measurements and other models' results for various sites along the Greek part of the hydrologic basin of Nestos (Nestos is a transboundary river extending along Greece and Bulgaria).Findings – The “PELNCON” results demonstrate a serious erosion threat for the Coastal area due to the sediment budget deficit of about 1.8 × 106 m3/year.Research limitations/implications – The developed model is subject to common structural weaknesses of c...

A B Murray - One of the best experts on this subject based on the ideXlab platform.

  • Coastal vulnerability of a pinned soft cliff coastline ii assessing the influence of sea walls on future Morphology
    Earth Surface Dynamics, 2014
    Co-Authors: Andrew Barkwith, Martin D. Hurst, Christopher Thomas, Michael A. Ellis, Pat Limber, A B Murray
    Abstract:

    Abstract. Coastal defences have long been employed to halt or slow Coastal erosion, and their impact on local sediment flux and ecology has been studied in detail through field research and numerical simulation. The non-local impact of a modified sediment flux regime on mesoscale erosion and accretion has received less attention. Morphological changes at this scale due to defending structures can be difficult to quantify or identify with field data. Engineering-scale numerical models, often applied to assess the design of modern defences on local Coastal erosion, tend not to cover large stretches of coast and are rarely applied to assess the impact of older structures. We extend previous work to explore the influences of sea walls on the evolution and morphological sensitivity of a pinned, soft-cliff, sandy coastline under a changing wave climate. The Holderness coast of East Yorkshire, UK, is used as a case study to explore model scenarios where the coast is both defended with major sea walls and allowed to evolve naturally were there are no sea defences. Using a mesoscale numerical Coastal evolution model, observed wave-climate data are perturbed linearly to assess the sensitivity of the Coastal Morphology to changing wave climate for both the defended and undefended scenarios. Comparative analysis of the simulated output suggests that sea walls in the south of the region have a greater impact on sediment flux due to increased sediment availability along this part of the coast. Multiple defence structures, including those separated by several kilometres, were found to interact with each other, producing complex changes in Coastal Morphology under a changing wave climate. Although spatially and temporally heterogeneous, sea walls generally slowed Coastal recession and accumulated sediment on their up-drift side.

Andrew Barkwith - One of the best experts on this subject based on the ideXlab platform.

  • Simulating the mesoscale impacts of sea wall defences on Coastal Morphology
    2014
    Co-Authors: Andrew Barkwith, Martin D. Hurst, Christopher Thomas, Michael A. Ellis, Pat Limber, Brad Murray
    Abstract:

    Solid Coastal defences are deployed in many countries to halt or slow Coastal erosion. Although the impacts on local sediment fluxes have been studied in detail, the non-local impact of a modified sediment flux regime on mesoscale Coastal Morphology has received less attention. Morphological changes imparted by defensive structures at these scales (decadal processes over tens of kilometres) can be difficult to quantify or even identify with field data. Difficulties in assessing the impact of these structures arise in the separation of natural and anthropogenic influences, both of which can be highly dynamic and non-linear. Numerical modelling allows these influences to be separated and the impacts of Coastal defensive structures to be assessed. We extend previous work (Barkwith et al., 2013) to explore the influences of sea walls on the evolution and morphological sensitivity of a pinned, soft-cliff, sandy coastline under a changing wave climate. The Holderness coast of East Yorkshire, UK, is one of the fastest eroding coastlines in Europe and is used as a case study for this research. Using a mesoscale numerical Coastal evolution model, stochastic wave climate data are perturbed gradually to assess the sensitivity of the Coastal Morphology to changing wave climate for both the defended and natural scenarios. Comparative analysis of the simulated output suggests that sea walls in the south of the region have a greater impact on sediment flux due to the increased sediment availability along this part of the coast. Multiple defended structures, including those separated by several kilometres, were found to interact with each other, producing a complex imprint on Coastal Morphology under a changing wave climate. Although spatially and temporally heterogeneous, sea walls generally slowed Coastal recession and accumulated sediment on their up-drift side.

  • Coastal vulnerability of a pinned soft cliff coastline ii assessing the influence of sea walls on future Morphology
    Earth Surface Dynamics, 2014
    Co-Authors: Andrew Barkwith, Martin D. Hurst, Christopher Thomas, Michael A. Ellis, Pat Limber, A B Murray
    Abstract:

    Abstract. Coastal defences have long been employed to halt or slow Coastal erosion, and their impact on local sediment flux and ecology has been studied in detail through field research and numerical simulation. The non-local impact of a modified sediment flux regime on mesoscale erosion and accretion has received less attention. Morphological changes at this scale due to defending structures can be difficult to quantify or identify with field data. Engineering-scale numerical models, often applied to assess the design of modern defences on local Coastal erosion, tend not to cover large stretches of coast and are rarely applied to assess the impact of older structures. We extend previous work to explore the influences of sea walls on the evolution and morphological sensitivity of a pinned, soft-cliff, sandy coastline under a changing wave climate. The Holderness coast of East Yorkshire, UK, is used as a case study to explore model scenarios where the coast is both defended with major sea walls and allowed to evolve naturally were there are no sea defences. Using a mesoscale numerical Coastal evolution model, observed wave-climate data are perturbed linearly to assess the sensitivity of the Coastal Morphology to changing wave climate for both the defended and undefended scenarios. Comparative analysis of the simulated output suggests that sea walls in the south of the region have a greater impact on sediment flux due to increased sediment availability along this part of the coast. Multiple defence structures, including those separated by several kilometres, were found to interact with each other, producing complex changes in Coastal Morphology under a changing wave climate. Although spatially and temporally heterogeneous, sea walls generally slowed Coastal recession and accumulated sediment on their up-drift side.

Achilleas G. Samaras - One of the best experts on this subject based on the ideXlab platform.

  • The impact of watershed management on Coastal Morphology: A case study using an integrated approach and numerical modeling
    Geomorphology, 2014
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Abstract Coastal Morphology evolves as the combined result of both natural- and human- induced factors that cover a wide range of spatial and temporal scales of effect. Areas in the vicinity of natural stream mouths are of special interest, as the direct connection with the upstream watershed extends the search for drivers of morphological evolution from the Coastal area to the inland as well. Although the impact of changes in watersheds on the Coastal sediment budget is well established, references that study concurrently the two fields and the quantification of their connection are scarce. In the present work, the impact of land-use changes in a watershed on Coastal erosion is studied for a selected site in North Greece. Applications are based on an integrated approach to quantify the impact of watershed management on Coastal Morphology through numerical modeling. The watershed model SWAT and a shoreline evolution model developed by the authors (PELNCON-M) are used, evaluating with the latter the performance of the three longshore sediment transport rate formulae included in the model formulation. Results document the impact of crop abandonment on Coastal erosion (agricultural land decrease from 23.3% to 5.1% is accompanied by the retreat of ~ 35 m in the vicinity of the stream mouth) and show the effect of sediment transport formula selection on the evolution of Coastal Morphology. Analysis denotes the relative importance of the parameters involved in the dynamics of watershed–coast systems, and – through the detailed description of a case study – is deemed to provide useful insights for researchers and policy-makers involved in their study.

  • An integrated approach to quantify the impact of watershed management on Coastal Morphology
    Ocean & Coastal Management, 2012
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Abstract Coastal areas are subject to various natural- and human-induced impacts affecting water quality and Morphology evolution. Regarding the latter, its correlation with watershed processes is self-evident, as natural streams in many cases constitute the largest sediment source for the Coastal environment. However, literature references that study concurrently both fields (i.e. terrestrial and Coastal) and their quantitative correlation are scarce. The present paper introduces and describes in detail an integrated approach to quantify the impact of watershed management on Coastal Morphology using numerical modeling. The core of the proposed methodology refers to a coupled-calibration approach of the watershed and the Coastal models, incorporating three scenarios of data availability regarding the parameters of interest (Coastal Morphology, overland sediment transport and Coastal sediment transport). To support the applicability of this approach, a brief presentation of its successful application for an area in North Greece is also presented. The study retains the viewpoint of Integrated Coastal Zone Management, and is deemed to provide an operational tool for future researchers and policy planners.

  • Modelling the impact on Coastal Morphology of the water management in transboundary river basins
    Management of Environmental Quality: An International Journal, 2008
    Co-Authors: Achilleas G. Samaras, Christopher Koutitas
    Abstract:

    Purpose – To study the impact of River Nestos (North Greece) dams construction on Coastal Morphology.Design/methodology/approach – In order to study the evolution of the Coastal Morphology in the area, an “one‐line shoreline change model” was developed (PELNCON). The model's input comprises the field characteristics, the wave characteristics at the breaker line and a “source” term for the sediment supply rate by River Nestos. The model calculates the shoreline change over a given period of time. The annually transported sediment quantity by the river is estimated using filed measurements and other models' results for various sites along the Greek part of the hydrologic basin of Nestos (Nestos is a transboundary river extending along Greece and Bulgaria).Findings – The “PELNCON” results demonstrate a serious erosion threat for the Coastal area due to the sediment budget deficit of about 1.8 × 106 m3/year.Research limitations/implications – The developed model is subject to common structural weaknesses of c...

Rosa M Chefaoui - One of the best experts on this subject based on the ideXlab platform.

  • landscape metrics as indicators of Coastal Morphology a multi scale approach
    Ecological Indicators, 2014
    Co-Authors: Rosa M Chefaoui
    Abstract:

    Abstract In this study, the aim was to assess how commonly used landscape metrics perform as predictors of Coastal shape. I examined nine metrics computed in FRAGSTATS to model the distribution of three Coastal features of the Iberian Peninsula: beaches, capes and gulfs. A multi-scale approach was used combining three extents, three resolutions and five moving-window sizes to implement generalized linear models (GLMs). This study has found that three landscape metrics (edge density, mean perimeter-area ratio and percentage of landscape) were good indicators for the three Coastal features, while mean shape index was only for beaches and gulfs. Differences in performance were found among the Coastal features and scales studied. GLMs revealed that the smallest extent (Levante coast) and resolutions (250 m2 and 1 km2) achieved better validation results, suggesting a higher suitability of these scales for detecting changes in vectorial shorelines. Differences in sensitivity and specificity were also found among models estimated from different moving-window sizes. The present study confirms previous findings on the high multicollinearity of landscape metrics, and the convenience of testing correlations in advance. Raster-based metrics computed from vectorial coastlines were effectively incorporated in spatial modeling. This research provides new insight into the use of Coastal shape to predict species distributions and other Coastal processes, serving as a base for future studies.

  • landscape metrics as indicators of Coastal Morphology a multi scale approach
    Ecological Indicators, 2014
    Co-Authors: Rosa M Chefaoui
    Abstract:

    a b s t r a c t In this study, the aim was to assess how commonly used landscape metrics perform as predictors of Coastal shape. I examined nine metrics computed in FRAGSTATS to model the distribution of three Coastal features of the Iberian Peninsula: beaches, capes and gulfs. A multi-scale approach was used combining three extents, three resolutions and five moving-window sizes to implement generalized linear models (GLMs). This study has found that three landscape metrics (edge density, mean perimeter-area ratio and percentage of landscape) were good indicators for the three Coastal features, while mean shape index was only for beaches and gulfs. Differences in performance were found among the Coastal features and scales studied. GLMs revealed that the smallest extent (Levante coast) and resolutions (250 m