: Abstract In this manuscript, we present the first version of the user-needs specification and the service-providers feasibility-analysis produced by the Monitoring Coastal Change from Space consortium for the Coastal Erosion project (2019 to 2021). The scope of the European Space Agency (ESA) Coastal Erosion project is the development and demonstration of innovative EO products that will be driven by end-user organizations and provided as services to agencies and communities with responsibilities of monitoring coastal change. This project involves end users from the UK (British Geological Survey), Canada (ARCTUS), Ireland (Geological Survey Ireland), Spain (MITECO assisted by IHCantabria) and France (IGNFI). This consortium led by ARGANS and supported by isardSAT and adwäisEO, is developing innovative approaches that best exploit the novel observational capabilities of both synthetic aperture radar (SAR - e.g. Sentinel-1) and multi-spectral optical (e.g. Sentinel-2) earth observation (EO) data. End-Users have defined seventeen products that represent the coastal change of different observable geometries (1D, 2D and 3D). We have clustered these into five general EO products: (1D) waterlines and shoreline indicators; (2D) Land Use, Land Cover and habitats maps; (3D) Topo Bathymetric Digital Elevation Models; (CSI) Coastal State Indicators. The rationale, benefits and feasibility of each type of product is presented. The next step is to expand this first version of the requirements the requirements from the broader community of end-users to produce a final consolidated version of the users-needs and feasibility analysis.
Coastal and estuarine landforms provide a physical template that not only accommodates diverse ecosystem functions and human activities, but also mediates flood and erosion risks that are expected to increase with climate change. In this paper, we explore some of the issues associated with the conceptualisation and modelling of coastal morphological change at time and space scales relevant to managers and policy makers. Firstly, we revisit the question of how to define the most appropriate scales at which to seek quantitative predictions of landform change within an age defined by human interference with natural sediment systems and by the prospect of significant changes in climate and ocean forcing. Secondly, we consider the theoretical bases and conceptual frameworks for determining which processes are most important at a given scale of interest and the related problem of how to translate this understanding into models that are computationally feasible, retain a sound physical basis and demonstrate useful predictive skill. In particular, we explore the limitations of a primary scale approach and the extent to which these can be resolved with reference to the concept of the coastal tract and application of systems theory. Thirdly, we consider the importance of different styles of landform change and the need to resolve not only incremental evolution of morphology but also changes in the qualitative dynamics of a system and/or its gross morphological configuration. The extreme complexity and spatially distributed nature of landform systems means that quantitative prediction of future changes must necessarily be approached through mechanistic modelling of some form or another. Geomorphology has increasingly embraced so-called 'reduced complexity' models as a means of moving from an essentially reductionist focus on the mechanics of sediment transport towards a more synthesist view of landform evolution. However, there is little consensus on exactly what constitutes a reduced complexity model and the term itself is both misleading and, arguably, unhelpful. Accordingly, we synthesise a set of requirements for what might be termed 'appropriate complexity modelling' of quantitative coastal morphological change at scales commensurate with contemporary management and policy-making requirements: 1) The system being studied must be bounded with reference to the time and space scales at which behaviours of interest emerge and/or scientific or management problems arise; 2) model complexity and comprehensiveness must be appropriate to the problem at hand; 3) modellers should seek a priori insights into what kind of behaviours are likely to be evident at the scale of interest and the extent to which the behavioural validity of a model may be constrained by its underlying assumptions and its comprehensiveness; 4) informed by qualitative insights into likely dynamic behaviour, models should then be formulated with a view to resolving critical state changes; and 5) meso-scale modelling of coastal morphological change should reflect critically on the role of modelling and its relation to the observable world.
In-situ Lagrangian-Acoustic Drogue (LAD) has been developed for estimating the sediment transport parameters in intertidal regions with very shallow water. The new drogue is equipped with a Global Positioning System (GPS), Acoustic Doppler Current Profiler (ADCP) and nephelometers. The accuracy of a current profile measured using this in strument is verified in two different conditions; uni-directional flow and multi-directional flow. The field observation results support the conventional concept of suspended sediment as a vertical balance between downward suspended sediment settling and upward turbulent diffusion fluxes. The results may indicate that the new drogue is adequate for estimating the sediment settling velocity in the field.
INTRODUCTION In engineering applications, the two most widely used model types up till now, for coastal evolution analyses, have been the one-line model and the profile change model. In one-line models the changes in shoreline position are assumed to be produced by spatial and temporal differences in the longshore sand transport rate (Hanson 1989, Hanson et al. 1988). This type of model is used to calculate shoreline changes that occur over a period of years to decades. Cross-shore transport effects, such as storm-induced erosion and cyclical movement of shoreline position associated with seasonal variation in wave climate, are assumed to cancel over a long enough simulation period or are accounted for through external calculations.
A priori no es posible conocer con certeza la forma en planta de un tramo de playa, debido principalmente al desconocimiento del clima marítimo al que estará sometido. En este trabajo se presenta un procedimiento de cálculo cuyo objetivo es el de cuantificar de forma objetiva la incertidumbre asociada a la predicción de la evolución de la línea de playa en términos de probabilidad. A partir de una base de datos oceanográficos y basados en los principios de las funciones ortogonales empíricas (FOE) se propone un procedimiento de simulación de las posibles secuencias de temporales. Estas secuencias sirven de entrada al modelo morfodinámico para generar una base de datos de posibles formas en planta. La probabilidad asociada a cada una de las posibles formas en planta es estimada empleando la técnica de FOE. Se estudia el caso de la evolución de una playa inicialmente recta aguas arriba de un espigón perpendicular a la costa que bloquea todo el transporte longitudinal de sedimentos, sobre la que se ha realizado una regeneración trapezoidal. Se emplea la solución analítica del modelo de una línea como modelo morfodinámico, con condiciones de contorno dependientes del tiempo y coeficiente de difusión no homogéneo.
This study represents the first attempt to map the sediment thickness spatial distribution along the Andalusian coastal zone by integrating various publicly available datasets. While prior studies have presented bedform- and sediment-type syntheses, none have attempted to quantify sediment thickness at the scale and resolution performed in this study. The study area has been divided into 18 physiographic zones, and we have used BGS Groundhog Desktop v2.6 software for 3D modeling and sediment thickness model calculations. We present here the modeling workflow, model results, and the challenges that we have encountered, including discrepancies in geological maps, difficulty managing data input for grain size/consolidation, and the need for additional geological information. We have compared the modeled sediment fractions of the unconsolidated material with 4194 seabed samples distributed along the study area and found that the differences between the modeled versus the sampled emphasized the importance of incorporating river contributions, particularly from the Guadalquivir River, into the model for more accurate results. The model intermediate and final outputs and the software routines used to query the sediment thickness model are provided as publicly accessible datasets and tools. The modeled sediment thickness could contribute to making quantitative predictions of morphological change at a scale that is relevant to longer-term strategic coastal management in Andalusia. The methodology and tools used for this study are transferable to any study area.
Abstract. We describe a new algorithm that automatically delineates the cliff top and toe of a cliffed coastline from a digital elevation model (DEM). The algorithm builds upon existing methods but is specifically designed to resolve very irregular planform coastlines with many bays and capes, such as parts of the coastline of Great Britain. The algorithm automatically and sequentially delineates and smooths shoreline vectors, generates orthogonal transects and elevation profiles with a minimum spacing equal to the DEM resolution, and extracts the position and elevation of the cliff top and toe. Outputs include the non-smoothed raster and smoothed vector coastlines, normals to the coastline (as vector shape files), xyz profiles (as comma-separated-value, CSV, files), and the cliff top and toe (as point shape files). The algorithm also automatically assesses the quality of the profile and omits low-quality profiles (i.e. extraction of cliff top and toe is not possible). The performance of the proposed algorithm is compared with an existing method, which was not specifically designed for very irregular coastlines, and to manually digitized boundaries by numerous professionals. Also, we assess the reproducibility of the results using different DEM resolutions (5, 10 and 50 m), different user-defined parameter sets related to the degree of coastline smoothing, and the threshold used to identify the cliff top and toe. The model output sensitivity is found to be smaller than the manually digitized uncertainty. The code and a manual are publicly available on a GitHub repository.
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