Climate variability impacts on coastal dune slack ecohydrology

The hydrological regime of freshwater systems plays a crucial role in shaping the dynamics of the different biological communities that inhabit them. Climate change is expected to cause major alterations in the hydrological regime of dune slacks by producing shifts in temperature, precipitation and evapotranspiration. Across seasons, we explore the controls on common water fleas (Cladocera) and aquatic plant communities relative to water level regime, water chemistry, weather and geomorphological setting, in a slack of the Sheskinmore dune system, Co. Donegal, northwest Ireland. Cladoceran abundance and diversity peak in summer, but also vary inter-annually, and drivers for this and hydrological variability are discussed. Vegetation is likewise affected by hydrology in a spatial sense, where distribution follows wet/dry patches of water. Water chemistry is more variable within the same season than across different years, particularly related to the drying out of the slack. Rainfall through 2016-2017 was lower than average and evapotranspiration showed higher values than average for the same time period. The influence on the slack of this decreased precipitation extended across successive seasons. The water table is the most important driver of slack ecology, with incidence on biological communities expressed by the increased variability inter-annually, as opposed to seasonal variation

Evaluating the Response of Mediterranean-Atlantic Saltmarshes to Sea-Level Rise

Saltmarshes provide high-value ecological services and play an important role in coastal ecosystems and populations. As the rate of sea level rise accelerates in response to climate change, saltmarshes and tidal environments and the ecosystem services that they provide could be lost in those areas that lack sediment supply for vertical accretion or space for landward migration. Predictive models could play an important role in foreseeing those impacts, and to guide the implementation of suitable management plans that increase the adaptive capacity of these valuable ecosystems. The SLAMM (sea-level affecting marshes model) has been extensively used to evaluate coastal wetland habitat response to sea-level rise. However, uncertainties in predicted response will also reflect the accuracy and quality of primary inputs such as elevation and habitat coverage. Here, we assessed the potential of SLAMM for investigating the response of Atlantic-Mediterranean saltmarshes to future sea-level rise and its application in managerial schemes. Our findings show that SLAMM is sensitive to elevation and habitat maps resolution and that historical sea-level trend and saltmarsh accretion rates are the predominant input parameters that influence uncertainty in predictions of change in saltmarsh habitats. The understanding of the past evolution of the system, as well as the contemporary situation, is crucial to providing accurate uncertainty distributions and thus to set a robust baseline for future prediction

Monitoring of Coastal Boulder Movements by Storms and Calculating Volumetric Parameters Using the Volume Differential Method Based on Point Cloud Difference

The measurements of boulder volume and axial length play significant roles in exploring the evolution of coastal boulder deposition, which provides a theoretical framework to examine the hydrodynamics of extreme wave events. At present, the application of structure-from-motion (SfM) to unmanned aerial system (UAS) imagery is one of the most used boulder surveying techniques. However, the monitoring of boulder movement and the accurate measurement of boulder morphometrics are rarely investigated in combination. In this study, UAS surveys were used to monitor moving boulders and measure boulder volumes using the volume differential method based on the differences of dense point clouds. This was undertaken at a site on the rocky shoreline of northwest Ireland in three repeated UAS surveys conducted in 2017, 2018, and 2019. The results from UAS monitoring and mapping of the distribution of 832 moving boulders in the study area over the 3-year period showed that boulders located in different zones of the coast vary significantly in their mobility. The main findings reveal that the theoretical error of the volume, obtained using the volume differential method, was estimated as 1–3.9%, which is much smaller than that of the conventional method of estimating volume using a tape measure

Coastal boulder movement on a rocky shoreline in northwest Ireland from repeat UAV surveys using Structure from Motion photogrammetry

The degree of boulder mobility in response to coastal storms likely varies spatially and temporally along rocky shorelines, but this is difficult to evaluate from field monitoring of individual boulders alone. Structure from Motion (SfM) photogrammetry can be used to analyse changes in shoreline geomorphology or boulder distributions over time and space from rocky shorelines. This study employs data from repeated Unpiloted Aerial Vehicle (UAV) surveys in 2017, 2018, 2019 and 2022 along a 1-km stretch of a rocky shoreline in northwest Ireland. SfM techniques were used to generate orthomosaics of the bedrock platform surface from which distributions and transport patterns of boulders were examined. Based on the identification of specific boulders that appear in images from successive time slices, 16–32 % of boulders had remained stationary (had either rotated or flipped on the spot, but experienced no change in boulder position), 18–39 % had moved but less than the calculated Root Mean Square Error (RMSE) value of 23 cm, and 29–66 % of boulders had moved greater than the RMSE value, and <29 m distance in one case. In addition, a significant minority of boulders also appeared or disappeared (3–23 %) between successive time slices, which may reflect their episodic transport to/from the sea or beyond the region of interest. Overall, the results indicate that boulder movement is highly variable over time and space and does not appear to correspond with episodic wave forcing. This is different to previous studies that have described a simple deterministic relationship between boulder movement and singular wave forcing events such as storms. Repeated UAV surveys provide a consistent methodology for understanding rocky shoreline and boulder dynamics, and can offer insight into shoreline sensitivity to regional wave climate operating under more normal or ‘average’ conditions

A morphological classification of coastal forelands, with examples from South Africa

Alongshore variations in the cross-shore width, and therefore volume, of sandy beaches are important because these reflect spatial variability in the operation of wave- and wind-driven processes taking place both at the shoreface and in the supratidal zone. One key geomorphic signature of variations in cross-shore beach width is the development of coastal forelands. Different foreland types have been described in the literature from very specific geomorphic contexts, but hitherto there has been no overarching classification scheme that genetically links these different foreland types, or considers them in the wider context of sandy beach dynamics. In order to achieve this aim, this study maps and inventorises 87 forelands from the South African coast (~2600 km long), and classifies these into four morphological types: salients, tombolos, cuspate forelands, and ramp forelands. These foreland types have different morphological properties, reflecting the interplay of coastal erosional and depositional processes and any antecedent conditions; and a varying balance of morphodynamic controls on their development and behaviour. These include variations in wave (and to a lesser extent wind) energy, sediment supply, and the presence of bedrock outcrops of different sizes, shapes and positions along the shoreline. Analysis of foreland morphology and dynamic behaviour, based on examples from South Africa, enables a better understanding of coastal forelands globally as integrated sediment systems and responsive to the range of forcings driving coastal change

Down the rabbit-hole: satellite-based analysis of spatiotemporal patterns in wild European rabbit burrows for better coastal dune management

Coastal dune systems in northwest Europe are facing conflicting challenges associated with climate change and human interventions in landuse and landscape management. Research over the last decade has highlighted a global stabilisation pattern in coastal dunes, fuelling long-standing debates surrounding conservation approaches. Dune erosion can be considered an important process within a naturally functioning dune system, but also a management challenge. The fossorial behaviour of burrowing mammals within coastal dunes is one driver of erosion that has long tested our perspectives on natural processes within dunes, but is understudied in coastal dune conservation and research. This is particularly the case for the wild European rabbit, a common naturalised invader of dune systems. In this study, the spatial distribution of wild European rabbits inhabiting a coastal dune system in Ireland is explored through geospatial mapping approaches using satellite and drone imagery, supported by spatial analyses and statistics. This reproducible approach has shown that rabbit activity fluctuates at inter-annual time scales that infer aligned changes in population, and that burrows clearly cluster in fixed dune habitats on landward slopes toward the rear of the dune system

Conceptualising and mapping coupled estuary, coast and inner shelf sediment systems

Whilst understanding and predicting the effects of coastal change are primarily modelling problems, it is essential that we have appropriate conceptual frameworks for (1) the formalisation of existing knowledge; (2) the formulation of relevant scientific questions and management issues; (3) the implementation and deployment of predictive models; and (4) meaningful engagement involvement of stakeholders. Important progress continues to be made on the modelling front, but our conceptual frameworks have not evolved at a similar pace. Accordingly, this paper presents a new approach that re-engages with formal systems analysis and provides a mesoscale geomorphological context within which the coastal management challenges of the 21st century can be more effectively addressed. Coastal and Estuarine System Mapping (CESM) is founded on an ontology of landforms and human interventions that is partly inspired by the coastal tract concept and its temporal hierarchy of sediment sharing systems, but places greater emphasis on a hierarchy of spatial scales. This extends from coastal regions, through landform complexes, to landforms, the morphological adjustment of which is constrained by diverse forms of human intervention. Crucially, CESM integrates open coastal environments with estuaries and relevant portions of the inner shelf that have previously been treated separately.In contrast to the simple nesting of littoral cells that has hitherto framed shoreline management planning, CESM charts a complex web of interactions, of which a sub-set of mass transfer pathways defines the sediment budget, and a multitude of human interventions constrains natural landform behaviour. Conducted within a geospatial framework, CESM constitutes a form of knowledge formalisation in which disparate sources of information (published research, imagery, mapping, raw data etc.) are generalised into usable knowledge. The resulting system maps provide a framework for the development and application of predictive models and a repository for the outputs they generate (not least, flux estimates for the major sediment system pathways). They also permit comparative analyses of the relative abundance of landforms and the multi-scale interactions between them. Finally, they articulate scientific understanding of the structure and function of complex geomorphological systems in a way that is transparent and accessible to diverse stakeholder audiences. As our models of mesoscale landform evolution increase in sophistication, CESM provides a platform for a more participatory approach to their application to coastal and estuarine management

Anders Burman, Politik i sak. C. J. L. Almqvists samhällstänkande 1839–1851 : Brutus Östlings Bokförlag Symposion. Stockholm/Stehag 2005

Saltmarshes provide high-value ecological services and play an important role in coastal ecosystems and populations. As the rate of sea level rise accelerates in response to climate change, saltmarshes and tidal environments and the ecosystem services that they provide could be lost in those areas that lack sediment supply for vertical accretion or space for landward migration. Predictive models could play an important role in foreseeing those impacts, and to guide the implementation of suitable management plans that increase the adaptive capacity of these valuable ecosystems. The SLAMM (sea-level affecting marshes model) has been extensively used to evaluate coastal wetland habitat response to sea-level rise. However, uncertainties in predicted response will also reflect the accuracy and quality of primary inputs such as elevation and habitat coverage. Here, we assessed the potential of SLAMM for investigating the response of Atlantic-Mediterranean saltmarshes to future sea-level rise and its application in managerial schemes. Our findings show that SLAMM is sensitive to elevation and habitat maps resolution and that historical sea-level trend and saltmarsh accretion rates are the predominant input parameters that influence uncertainty in predictions of change in saltmarsh habitats. The understanding of the past evolution of the system, as well as the contemporary situation, is crucial to providing accurate uncertainty distributions and thus to set a robust baseline for future predictions

Two-dimensional reduced-physics model to describe historic morphodynamic behaviour of an estuary inlet

Understanding medium to long term morphodynamic change is important for sustainable coastal and estuary management. This paper analyses morphodynamic change of a complex estuary inletwhich is subjected tomultiple environmental drivers and proposes a reduced physics model to explain the historic medium term morphodynamic change of the inlet. The analysis shows that even though the estuary inlet undergoes multiscale morphological change, the changes that take place over a timescale of several years are more significant and important. The reduced physics model suggests that this simplified modelling approach is able to recognise principal historic morphodynamic trends in the estuary. However, the length and quality of the inlet bathymetry data set limits the applicability of the models and the quality of model outputs