Morphological evolution of creek networks in 10 restored coastal wetlands in the UK

Coastal wetlands provide crucial ecosystem services including flood protection and carbon storage, but are being lost rapidly worldwide to the combined effects of sea-level rise, erosion and coastal urbanisation. Managed Realignment (MR) aims to mitigate for these losses by restoring reclaimed land to tidal influence. Data of creek evolution is critical to assess the performance of design strategies and improve design and implementation practices. This data descriptor provides a dataset of the horizontal morphological evolution of creek systems from various initial conditions in 10 MR schemes across the UK. Using a semi-automated workflow, morphological creek parameters were extracted from 52 lidar datasets at 1 m horizontal resolution spanning 2 to 20 years post-breach. This constitutes the most comprehensive systematic monitoring of MR creek morphology to date. The dataset will assist future MR design and provide baseline morphological information for ecological and biogeochemical surveying

Carbon Storage and Distribution in a Temperate Saltmarsh – A case study of the Ribble Estuary, UK

Temperate saltmarshes serve as important stores of blue carbon and climatic regulators, however little is currently known about the contemporary carbon storage capacities of UK saltmarshes. This study quantifies the carbon storage capacity of the saltmarshes in the Ribble estuary and analyses the influence of elevation, gradient and watercourse proximity on carbon distribution. The study specifically focusses on carbon stored within the ‘active section’ which is comprised of the above-ground biomass and surface organic layer, defined as the ‘active layer’ in this research. Overall, the findings indicate that 1.26 x 107 kg and 12.9 x 107 kg (3.s.f) of carbon is stored within the above-ground biomass and active layer sediment respectively, although carbon is unevenly distributed between the sub-environments that comprise the saltmarshes of the Ribble. Whilst elevation, gradient and watercourse proximity are recognised to exert an interconnected influence on sub-environment and carbon distribution, only gradient and watercourse proximity were found to be statistically significant. In all sub-environments watercourse proximity exhibits a standardised influence between 50.1% and 72.0% greater than gradient. The overall distribution findings rebuke the simple elevation ramp model of distribution and support the theory that saltmarsh sub-environment and carbon distribution is controlled by a multitude of interconnected ecogeomorphological factors. The study also highlights the overall active section carbon storage capacity of the Ribble saltmarshes could decrease by 23.8%, 30.7% or 30.9% of the 2012 capacity by 2100 under the respective RCP 2.6, 4.5 and 8.5 (50th percentile) sea level rise scenarios. There is also the potential for greater degradation and carbon loss to occur as result of sea level rise driven headward expansion of creeks given the significant influences of watercourse proximity and gradient on sub-environment distribution. Therefore, it is important future shoreline management policies are adapted to limit future degradation in order to allow the saltmarshes of the Ribble to continue to act as an important store of blue carbon

Changes in coastal sediment dynamics due to managed realignment

Consolidation of the ecosystem services approach and concerns about climate change impacts are leading to a paradigm shift in the management of coastal erosion and flooding risk. Working with nature approaches aiming to restore the adaptive capacity of environments to respond to dynamic conditions are now promoted in a growing number of local and national strategies. In England, for example, Shoreline Management Plans foresee 10% of the coastline to be realigned by 2030 and 15% by 2060. Despite over 100 projects implemented in Europe, only few studies discuss the effects of managed realignment on coastal and estuarine sediment dynamics. This paper presents a conceptual model for the longer term evolution within and adjacent to management realignment sites and contrasts with evidence from published field data

Understanding space and habitat use of the Near Threatened Eurasian Curlew to inform the value of habitat restoration schemes for the species' conservation

Intertidal habitats and terrestrial habitats connected to estuaries are subject to multiple anthropogenic pressures including the indirect effect of climate change (i.e., sea-level rise). To build sustainable coastal defences and create intertidal habitats in estuaries, managed realignment (MR) sites are created. These habitats are of potential value for wintering waders yet we know little about their long-term development and utilisation by waders (Charadriiformes; also referred to as shorebirds), for example, Eurasian curlew (Numenius arquata). The species is categorised as Near Threatened by the International Union for Conservation of Nature (IUCN) and uses both estuarine and non-estuarine habitats in winter. Understanding small-scale spatial patterns in the use of estuaries and of created intertidal habitats is essential in predicting the impact of habitat loss and designing effective compensatory sites for waders. In ecological models, e.g., individual-based models (IBMs), assumptions about animal movements are often made using a priori information on space use and habitat use. The first chapter of the thesis (Chapter 1) aims to provide background to the project and to review the use of modern telemetry and predictive modelling in assessing the success of estuarine habitat creation for waders. This thesis then examines the long-term suitability of managed realignment sites for waders in response to physical changes (i.e., in the elevation of created intertidal areas) (Chapter 2), and uses high-resolution tracking data to examine individual, sexual and temporal variation in the winter home range (Chapter 3) and habitat selection (Chapter 4) of Eurasian curlew. Furthermore, movement data – derived from GPS-tracked curlew – were incorporated to define parameters of an individual-based model, developed to predict the impact of managed realignment and other environmental changes. Using data on behaviour and fine-scale habitat use from the GPS-tracked Eurasian curlew, I also validated the model's predictions (Chapter 5). I found the foraging numbers of the four key waterbird species that colonised the MR site to decline above a certain elevation, and thus over time with accretion of the site, with this effect being most pronounced for the Eurasian curlew (Chapter 2). Using a sample of 21 GPS-tagged birds, I found Eurasian curlew to be faithful to foraging and roosting areas on their coastal wintering grounds, including a habitat creation site. Home range of Eurasian curlew was small (555.5 ha +/-SD 557.9 ha) and varied slightly in size through the non-breeding season (September to March). Home range sizes were greater at night than in the day, and showed high inter-individual variability which was not related to sex and thus potential differences in resource use (Chapter 3). I also found that Eurasian curlew’s core ranges were restricted to one to two distinct patches on intertidal flats with some overlap. Eurasian curlew preferentially selected saltmarsh and the MR site at night, presumably for roosting (Chapter 4). Finally, I successfully parameterised an individual-based model (Chapter 5). The model was able to successfully predict the impact of habitat creation on the abundance of waders supported by a discrete area of the Humber Estuary. Our overall results provide a collective understanding of the responses of waders to the creation of the managed realignment site and of the space and habitat use of Eurasian curlew. The results have been crucial in informing and validating simulations from the individual-based model

Tidal marsh restoration for flood risk mitigation: The effectiveness of managed realignment at Freiston Shore, Lincolnshire, UK

The ecosystem services delivered by coastal wetlands are among the most valuable onthe planet, including the mitigation of climate related risks by sequestering carbon at rates several orders of magnitudes faster than tropical rainforests as well as the provision of natural coastal protection. Despite their ecological and socio-economic importance, coastal wetlands have been lost on a large scale in the past centuries, mostly due to human induced stress factors. The projected acceleration of Sea-Level Rise (SLR) may exacerbate the vulnerability of wetlands in the coming centuries, particularly in case of limited accommodation space due to the presence of anthropogenic infrastructure. Increasing flood risk for low lying coasts and the continued reliance on traditional engineered solutions that have become economically and ecologically unsustainable in many locations require the development of new measures to mitigate these risks. In the last decades, Managed Realignment (MR) has been implemented with the aim to provide a cost effective and ecologically sustainable alternative to conventional coastal defence schemes. MR constitutes one of several Nature-Based Solutions (NBS) making use of the natural wave and surge attenuating capacity of coastal wetlands and their ability to build up vertically at rates often higher than historical SLR. MR involves the realignment of river, estuary or coastal defences to (re-)establish tidal exchange, supporting the formation of coastal wetlands such as mudflats and saltmarshes. Yet, an important knowledge gap constitutes lacking evidence on the true protective value of MR, which fosters political and societal opposition, ultimately counteracting large scale coastal restoration efforts. This thesis tackles the above knowledge gap in a combined approach, including field measurements and hydrodynamic modelling, to study the effectiveness of High Water Level (HWL) attenuation across one of the earliest and, at time of establishment, largest coastal MR schemes of the United Kingdom: Freiston Shore, located in Lincolnshire on the east coast of England. Between August and October 2017, a series of 16 water level loggers was deployed across the MR site and the adjacent natural saltmarsh to measure the reduction of peak water levels during the highest tides of the year. Subsequently, these data were used to calibrate and validate a hydrodynamic model of the study area, which enabled studying the effects of MR scheme design on the site’s HWL attenuation capacity during these tides. In a last step, the model was implemented to investigate HWL attenuation rates inside the MR site under the influence of very high storm surge levels, by additionally identifying MR width thresholds for HWL attenuation in relation to surge height and vegetation cover. The main findings of this thesis are: 1) The MR site of Freiston Shore does not provide effective HWL attenuation under all measured conditions. 2) At the open coast of Freiston Shore, only large and wide MR sites can effectively attenuate very high tides, and the reduction of storm surges with return periods of more than ten years requires MR widths of >1148 m (measured perpendicular to the coastline). 3) Increased vegetation cover and larger MR widths enable the attenuation of even higher surges. 4) Breaching dikes should be preferred over complete dike removal when coastal protection is the target of MR implementation. Three priority areas for future research are recommended: 1) Generating more in situ data on MR internal water level dynamics and HWL attenuations, particularly under storm surge conditions. 2) Freiston Shore’s HWL attenuation function is particularly effective when tidal exchange is restricted through narrow dike breaches, which could also be achieved by applying sluices or culverts (i.e. Regulated Tidal Exchange (RTE)). However, this should be balanced against reduced sedimentation rates, limited MR drainage and vegetation establishment, and the potential erosion and widening of dike breaches, which may all result from breaches being designed too narrow or RTE. 3) Investigating the effectiveness and applicability of several MR schemes and other NBS to mitigate flood risks on a regional scale

The evolution of embryonic creek systems in a recently inundated large open coast managed realignment site

Managed realignment (MR) schemes are being implemented to compensate for the degradation of coastal habitats. However, evidence suggests that MR sites have lower biodiversity than anticipated, which has been linked to poor drainage. Despite creek networks playing an important role in enhancing site drainage in natural intertidal environments, there remains a shortage of data on the formation and evolution of creeks within MR sites. This study evaluates creek development at the Medmerry Managed Realignment Site, UK. Creek development is investigated using differential global positioning system(dGPS) data, supported by sedimentological analyses and a high-resolution digital surface model (DSM) derived from images taken using a small unmanned aerial vehicle. Measurements indicated that creeks will develop relatively quickly, but are influenced by differences in the sub-surface sedimentological conditions. A suitable level of agreement was found between the DSM and dGPS measurements, demonstrating the appropriateness of this method to study creek development within intertidal environments at a higher resolution than traditional surveying techniques. These results are used to propose the collapseof sub-surface piping as the primary creek formation mechanism. Findings are discussed in terms of increasing the success of MR schemes and enhancing site design to maximise the ecosystem services provided

Geoconservation principles and protected area management

Geoconservation includes the protection of geoheritage features and geosites and the application of geoconservation principles more generally in the sustainable management of protected areas and in the wider landscape. This article reviews: 1) geoconservation principles and objectives for geosite management planning; and 2) the wider relevance of geoconservation and how the application of geoconservation principles across the full range of IUCN protected area management categories, UNESCO Global Geoparks and Biosphere Reserves, World Heritage sites, Ramsar sites and marine protected areas would benefit conservation of biodiversity and geodiversity and support wider nature conservation objectives, including climate change adaptation, connecting people and nature and sustainable development. In particular, the concepts of ‘nature and people’ and ‘conserving nature's stage’ provide opportunities for developing more holistic approaches to nature conservation.Publisher PDFPeer reviewe

Enhancing dykeland resiliency in a hypertidal estuary

xiii, 189 leaves : colour illustrations, colour maps ; 29 cmIncludes abstract and appendices.Includes bibliographical references (leaves 159-176).Dykelands are low-lying areas created by the reclamation of saltmarshes by the construction of dykes and other infrastructure which are made resilient to the impacts of climate change by the presence of robust foreshore saltmarshes seaward of dyke infrastructure. This study looked at the impact flood and erosion adaptation strategies have had on hypertidal saltmarshes at various spatial and temporal scales in the Bay of Fundy, Canada. While the primary cause of significant foreshore saltmarsh erosion and progradation were a result of natural processes, several features were found to have precipitated significant changes in the position of the foreshore. Borrow pits, which are excavated swaths of saltmarsh excavated from the foreshore for dyke topping material were also studied using an unmanned-aerial-vehicle and structure-from-motion software. Eight out of the 13 borrow pits studied were found to be infilling at a rate which would only reduce dykeland resiliency in the short-to-medium term