Over the past 20 years, globally-averaged sea level has risen at a rate near the upper end of the sea level projections of the Intergovernmental Panel on Climate Change. With many coastal areas being located close to or below Mean Sea Level (MSL), there is a growing threat of them being engulfed. A series of tide gauges (TG) located at coastal sites measure the MSL. Tide gauge records of mean sea level are an important data set for the computation of long-term estimates of changes in sea level, for both regional and global analyses. These measurements, however, contain deformation due to sea level variation and vertical land motion (VLM). In order to fully understand long-term sea level changes and to thereby plan effectively for flood risk management, there is a need to identify the component of the change in mean sea level measured by a tide gauge that is due to changes in land level. Measurements obtained from precise levelling, continuous Global Positioning System (CGPS) and Absolute Gravity (AO) at, or close to, tide gauges are used to correct the tide gauge records for VLM. However, these techniques are only capable of providing a point-wise estimate for VLM, i.e. at the COPS antenna installation. Persistent Scanerer Interferometry (PSI) is a powerful technique for identifying long-term changes in vertical land motion with millimetric accuracy and it has been successfully applied to deformation monitoring in both urban and rural areas. The PSI technique takes advantage of a large number of multi-date imaging radar data to identify and analyse dense arrays of naturally occurring, consistently bright or coherent points in the images. Unlike precise levelling, COPS and AO, PSI is capable of providing estimates over a wide spatial extent. However, like precise levelling, these estimates are relative as opposed to the absolute VLM provided by CGPS and AG. This research in this thesis will investigate the application of PSI to aid monitoring of tide gauge sites in the United Kingdom. The primary research question is whether the Interferometric Synthetic Aperture Radar (lnSAR) time-series analysis can provide patterns of regional deformation of coastal and inland areas and whether this technique can be used to assess the stability of the tide gauge sites and its use in long term sea level monitoring. Four study areas with various settings were selected based on the extent of urbanisation, available imagery and the existence of other geodetic information at the site. These test sites were Newlyn and Sheerness (both characterised as rural areas with sparse urban regions), Liverpool and North Shields (both highly urban). In addition to the differences in population density, these four test sites also covered a range of geological conditions around the coast. This research considered PSI processing difficulties that arise from the application of this technique to coastal areas. These included the ambiguities arising from the phase unwrapping of the edge PS points (knovo11 as a "boundary problem"), the choice of an optimal reference point, and the effect of the ocean tide loading on the estimated PS velocities. It was shown that deformation can be properly detected, even when located on the coastline. Although the ocean tide loading can introduce displacement gradient of the order of a few centimetres per l00km in the interferogram, -this study has shown that the ocean tide loading has little effect on the PS points velocity estimates. This research has also investigated the possible ways of integrating the CGPS deformation with the PSI. By choosing the nearest PS point (on a ground considered stable) to the CGPS station as a reference, and adding on the difference between the PSI and CGPS deformation to all PS points, velocity estimates can be obtained that are similar to those reported by CGPS. The assessment of the application of PSI to the four coastal sites consisted of: a) considering the underlying regional deformation for better understanding of the deformation processes and their possible causes and b) studying the local deformation in close proximity to the tide gauge and the CGPS station to assess the stability of the site. As expected, the PSI results for the sites with sparse urban areas gave very poor coherence and too few PS points to fully understand the deformation pattern of the structure supporting the tide gauge and the CGPS station. However, for the highly urban areas, a good PS point density was obtained, revealing the deformation pattern in the area. By comparing the land motion present at the coast with that of a more inland area, it was shown that, for most sites, there is negligible differential motion, although, in few cases a more complex deformation pattern was revealed. It was also shown that the highly non-linear deformation pattern was not reflected in the linear velocity estimates, highlighting the importance of investigating the non-linear deformation profile of the PS point.

Intertidal habitats around Europe have been significantly degraded over the last century, and longer, due to direct human destruction for a variety of purposes. Through undertaking a comparative study with other Western European countries, this research sought to explore similarities and differences, and hence predict the future application of Managed Realignment (MR) in the case study countries, and draw conclusions for the application of MR to elsewhere. The situation in Scotland, England, the Netherlands, and Germany was studied in an in-depth fashion, whereas an exploratory analysis of the status quo in Spain, France, Belgium and Denmark was also undertaken. This research employed methodologies associated with human geography to achieve its aims, specifically the combination of a broad literature review process with extensive direct contact with coastal professionals and experts, both through quantitative surveys and qualitative face-to-face interviews. This analysis found that two main factors dominate as drivers for the use of managed realignment in Western Europe – a desire to make up for past and current losses of intertidal habitats and the need to upgrade existing defence structures. RTE in contrast tends to by only driven by the first factor. A surprisingly large number of schemes were found across Western Europe (at least 89), employing a wide variety of techniques. It was found that whilst problems encountered during implementation, such as public opposition and planning delays, are often fairly similar across Europe, drivers have varied significantly. The most common lesson implementers across Europe wished to convey to others was to engage the public and major stakeholders at the earliest opportunity in the planning process. This research indicates that schemes have evolved since they were first implemented in Europe in the late 1980s; from often ad-hoc, barely modelled and monitored schemes, to a new generation of sophisticated multi-driver schemes, which tend to be meticulously planned, consulted and monitored.

Isolation basins from Northwest Scotland provide the longest near-field records of relative sea-level (RSL) change in the world (0 to > 16kyr BP). These archives contributed to quantitative models of glacial isostatic adjustment since the last glacial maximum. Isolation basin RSL reconstructions have been primarily based on salinity reconstructions from biological data such as foraminifera and diatoms. However, preservation problems and non-analogue situations can limit their usefulness. Therefore, it is necessary to identify other proxies from isolation basin to improve RSL reconstructions. Also isolation basin sediments are potentially high-resolution records of climate change from both the land and the oceans simultaneously, but little research has been undertaken. This thesis presents the results of a range of isotopic and geochemical measurements that were thought to be suitable proxies for palaeosalinity and palaeoclimate reconstructions. Tephrochronology was also applied to improve the existing geochronological controls of isolation basin sequences by attempting to identify Icelandic tephra layers. A combination of isotopic measurements; δ(^13)Corg, C/N ratios δ(^13)Ctoram, δ(^18)Otoram, (^87)Sr/(^86)Sr from foraminifera and δ(^13)Odiatoms, were preformed on contemporary and fossil archives. Results show δ(^13)Corg, C/N ratios measurements are as sensitive indicators of palaeosalinity, as biological reconstructions on Holocene aged sediment. Overall this thesis highlights the benefits of multi proxy palaeosalinity studies in order to gain a fuller understanding of the complex changes isolation basins experience during an isolation or connection events. A climate signal from an isolation basin that experienced a gradual isolated over the Holocene has been detected for the first time using geochemical techniques biogenic silica (BSi02) and total organic carbon (TOC).

Salt-marsh sediments can provide important achives of past sea levels if they can be securely dated. This thesis investigates eight methods for dating salt-marsh sediments. These include traditional and established dating methods (¹⁴C dating and the radionuclides ¹³⁷Cs and ²¹ºPb) and more novel approaches to dating the deposition of salt-marsh sediments (palaeomagnetic dating, the use of' atmospheric stable lead deposition, tephra chronologies, pollen markers, SCP analysis and the use of atmospheric ¹⁴C 'bomb spike' and high-precision AMS ¹⁴C measurements). Sites were selected to provide contrasting sediment sequences that differed both in lithology and accumulation rates and included salt marshes from the Taf estuary (southwest Wales), the Arne Peninsula (southern England) and Vioarholmi (western Iceland). The investigations in the Taf estuary produced the first palaeomagnetic chronology from a salt marsh. From the Arne Peninsula this thesis reports the first successful use of bomb-spike calibrated ¹⁴C analyses in a salt marsh as well as high-precision AMS ¹⁴C ages for the 'problem' period AD 1700-1950. Stable Pb analysis at all three sites produced a number of chronological markers that signalled the timing of increases in industrial Pb emissions, and the later use of Pb petrol additives during the 20th century. In addition, a unique isotopic signal, attributed to the working of Pb metal during the height of the Roman Empire in Europe, was found in the Icelandic sediments. The radionuclides ²¹ºPb and ¹³⁷Cs produced precise chronologies for the last 100 yr in the Taf estuary. However, post-depositional mobility of ¹³⁷Cs on the Arne Peninsula and low ²¹ºPb concentrations at Vioarholmi prevents the construction of reliable ²¹ºPb and ¹³⁷Cs chronologies. In contrast, the use of tephra at Vioarholmi, and pollen and spheroidal carbonaceous particle markers on the Arne Peninsula, showed great potential as independent unique-event dating tools that could be used to constrain conventional ¹⁴C calibrations. Finally, the chronological information produced by all the individual methods was combined to construct an integrated chronology for each site. This approach significantly reduced age uncertainties and produced higher resolution, and more robust, salt-marsh sedimentation histories

In the last twenty years, the importance of sediment transport in the swash zone has been established. The disproportionately high sediment transport rates in this region make its inclusion in general nearshore models vital. As part of this U.K. Natural Environmental Research Council project (grant number: NERlA/S/1999/00144), high frequency (8 Hz) measurements were made of the water depth and vertical variations in suspended sediment concentration and water velocity, using state-of-the-art instrumentation. Further measurements included nearshore and offshore wave conditions, tidal elevations, wave run-up limits, groundwater variations, sediment grain size distributions, beach slopes and changes in morphology at time-scales from minutes to weeks. Fieldwork was carried out on a gently-sloping (tan p - 0.03; d50 ~ 0.27 mm) and steep beach (tan p - 0.09; d50 ~ 0.55 mm). Both experience similar wave climates which allows a direct comparison between hydrodynamics and sediment transport in the swash zone.

The response of regional tidal dynamics to sea level rise (SLR), tidal power plants (TPPs), land reclamation and a combination of the above was investigated using two tidal models. The impact of SLR was investigated on, and tidal models validated for, the European Shelf, the Bay of Fundy and the Bohai Sea. The tidal response varied greatly between regions; however the method in which SLR was implemented within the tidal models also caused significant variation in the response. When sea level was increased but no land was allowed to flood (i.e. the coastline did not move) the change in tidal by processes that involved the increased water depth (such as tidal resonance). However, when land was allowed to flood the response was governed by the change in the spatial distribution of tidal energy dissipation. The maximum extractable tidal energy and the impact of the extraction of this energy in the Minas Passage were investigated on the tidal regime of the Bay of Fundy. It was found that the impacts were significant and wide spread. Furthermore, it was demonstrated that SLR could increase the maximum extractable tidal energy. The tides of the Bay of Fundy are close to resonance and SLR with no flooding caused the system to move closer to resonance. However when flooding was enabled the system did not move towards resonance, suggesting the change in tidal dissipation dampened the response. The Bohai Sea has undergone rapid and extensive natural and anthropogenic land reclamation. Tidal gauge observations show that the tidal regime has responded significantly to these changes. We have been able to reproduce these changes using a tidal model, furthermore, future simulations show that the tides of the Bohai Sea may have become more sensitive to impacts of SLR. It was found that the regional tides investigated were particularly sensitive to changes in the spatial distribution of ideal energy dissipation. As demonstrated by the investigation of practical scenarios.

À l'échelle du monde, les littoraux peuvent se diviser en différentes catégories : les côtes rocheuses, sableuses, vaseuses et mixtes. Cependant, les littoraux meubles sableux et vaseux sont retrouvés régulièrement mélangés sur différentes façades côtières mondiales. Des apports de vases temporaires ou permanents sont en effet observés sur des plages sableuses. Ces environnements mixtes atypiques, qui couplent alors les processus d’érosions, de transports et de dépôts associés à la fois aux sédiments cohésifs et non cohésifs, ont été peu étudiés. Afin d’identifier les forçages des variations morpho-dynamiques sur des environnements sableux et mixtes, quatre plages sablo-vaseuses ou entièrement sableuses de type Low-Tide-Terrace ont été suivies mensuellement sur deux années en baie et estuaire de la Vilaine (Bretagne Sud). Des suivis hydro-morpho-sédimentaires spécifiques à haute résolution et des suivis par photogrammétrie ont été menés ponctuellement sur ces sites. À l'échelle régionale, ce travail met en évidence le rôle de la morphologie initiale et l’héritage géologique régional dans la réponse morphologique du littoral de la baie de Vilaine aux conditions d’énergie extrêmes. La capacité de résilience à moyen-terme du littoral des plages de Bretagne Sud a été démontrée. Dans une approche plus spécifique, un comportement morphodynamique d'une plage sablo-vaseuse proche de celle d'une plage uniquement sableuse a été observé lors des phases de haute énergie. Les variations d’altitudes du platier vaseux et des modelés sédimentaires en ridges and runnels sont principalement contrôlées par l’énergie des vagues mais également par les propriétés physiques des sédiments et particulièrement celles liées à l'interaction entre le sable provenant de la section réflective et la vase de la section dissipative. La capacité d’érosion du platier vaseux par les vagues est potentiellement diminuée au niveau des interfaces des sédiments cohésifs et non-cohésifs. / At the world scale, coastal areas can be divided in several categories: rocky, sandy, muddy and mixed coasts. However, these sedimentary coasts are regularly found mixed. Temporary or permanent mud inputs are observed on the sandy beaches. These atypical mixed environments, coupling erosional, transports and deposits processes associated to cohesive and non-cohesive sediments have been poorly studied. So, understanding theirs morphological and sedimentary dynamics and the identification of regional and local forcings driving them are essential. Four sandy-muddy or fully sandy Low-Tide-Terrace beaches from the bay and estuary of Vilaine (South-Brittany) have been monthly monitored over two years to characterize their morphodynamics beahaviors. Specific monitoring of coupled hydrodynamics and morpho- sedimentary surveys and photogrammetry experiments have been conducted on mixed sandy- muddy or full sandy beaches. At a regional scale, this work highlights the role of the initial morphology and regional geology inheritance on the morphological response of the littoral zones to extreme energy conditions. Despite some erosion patterns in local parts of beaches, particularly close to shore protection structures, the mid-term recovery capacity of the south-Brittany coastal area after extreme wave energy conditions have been proved. In a more specific approach, the works regarding the sandy- muddy beach dynamic show a morphodynamics behaviour close to that of a fully sandy beach during high energy event. The mudflat elevation changes and the dynamic of the ridges and runnels sedimentary patterns are mainly controlled by the incoming waves but also by the own physical properties of the sediment, particularly those induced by the interaction between the sand from the reflective section and the mudflat. A sand deposit between mud layers potentially decreases the wave erosion capacity on the mudflat.

Coastal populations are growing at a rapid pace and this is being accompanied by an increased investment in infrastructure at the coastal zone. Combined with this is the concern of enhanced coastal flooding due to rising sea levels and climate change. Hence, it is of utmost practical importance that probabilities of current and future extreme sea level are accurately evaluated so that the changing flood risk can be assessed and defences upgraded where appropriate. This thesis tests the hypothesis that changes in extreme still water level can be approximated by just adding changes in mean sea level to current return levels estimated from measured data, for the English Channel region. A data archaeology exercise has been undertaken to extend the sea level records along the UK south coast. This exercise increased the sea level data set for this region by 173 years. These new records have been analysed along with existing data to determine rates of change in both mean and extreme sea level, and to estimate probabilities of extreme sea level using four statistical methods: (i) the annual maxima method; (ii) its extension to the rlargest annual events method; (iii) the joint probabilities method; and (iv) the revised joint probabilities method. Relative mean sea-level trends vary by between 0.8 and 2.3 mm/yr around the Channel over the 20th century. These trends have been estimated using a new approach, in which the coherent part of the sea level variability around the UK is defined as a single index. This is then subtracted from the sea level records prior to fitting trends. The recent high rates of mean sea-level rise observed over the last decade are not unusual on a century scale context. The tidal and non-tidal components of sea level, along with tide-surge interaction, have been separately analysed for trends before analysing variations in extreme sea levels. There is evidence for an increase in extreme sea levels during the 20th century, but at rates not significantly different to that of mean sea level. There is no evidence of a longterm increase in storm count, duration or intensity. The revised joint probabilities method is found to out perform the other statistical methods, in terms of prediction errors. Results confirm that changes in extreme sea levels during the 20th century can be estimated, to an accuracy of 0.1 m, by simply adding mean sea level changes to return levels estimated from measured data. The return levels should be estimated using the revised joint probabilities method wherever possible.

À l’interface terre/mer et nature/société, les littoraux sont des territoires complexes et très attractifs où se déploient divers usages et pratiques qui génèrent de nombreux conflits et dégradations. Il existe aujourd’hui un consensus global quant à la nécessité de préserver ces espaces et la biodiversité qu’ils abritent. Depuis plusieurs décennies, c’est la gestion intégrée de la mer et du littoral (GIML) qui est prônée à l’échelle internationale comme la solution pour répondre aux problématiques rencontrées sur les zones côtières. L’approche s’inscrit dans la démarche du développement durable et elle tente de réconcilier l’usage des ressources et la conservation de la biodiversité. Une profusion de projets a vu le jour un peu partout à travers le monde et beaucoup de moyens humains et financiers ont été mobilisés à cet effet. Mais elle rencontre des difficultés importantes aussi bien dans sa mise en pratique que dans son évaluation. Or ce dernier point est largement reconnu comme un outil indispensable dans la planification et la gestion des projets et des programmes. Cette thèse propose donc une méthode d’élaboration d’indicateurs pour le suivi et l’évaluation des politiques de GIML qui permet d’apprécier les écarts entre les ambitions de protection de l’environnement, de développement économique et de bien-être social qui sous-tendent l’approche et les actions réalisées sur le terrain. Pour ce faire, quatre études de cas dans la Caraïbe ont été choisies. Il s’agit du Parc marin de Saba, de la Soufrière Marine Management Area (Sainte-Lucie), du groupe Nature Seekers (Trinidad) et du contrat de baie de Fort-de-France (Martinique). Ces expériences sont toutes citées comme des réussites en termes de gestion intégrée du littoral et comme des exemples à suivre. Mais répondent-elles réellement aux objectifs de la démarche ? La grille d’analyse proposée permet d’avoir une autre lecture des résultats de ces processus et de tirer des enseignements plus généraux pour la mise en pratique de la GIML. / At the interface of land and sea, and at the interface of nature and society, coastal areas are complex and very attractive territories where diverse uses and practices generate many conflicts and degradations. There is now a global consensus on the need to preserve these areas and their biodiversity. For several decades, Integrated Coastal and Ocean Management (ICOM) has been advocated internationally as the approach to address the problems encountered in coastal areas. The approach is a key paradigm for the sustainable development of coastal zones and it tries to reconcile the use of resources with the conservation of biodiversity. A large number of projects have been implemented around the world and many human and financial resources have been mobilized for this purpose. But ICOM implementation and evaluation remain much of a challenge. This last point is widely recognized as an indispensable tool in project and program planning and management. This thesis therefore proposes a methodology for the development of indicators for the monitoring and evaluation of GIML initiatives, which makes it possible to appreciate the gaps between ambitions for environmental protection, economic development and social welfare. Underpin the approach and the actions carried out on the ground. To do so, four case studies in the Caribbean were selected. These include the Saba Marine Park, the Soufrière Marine Management Area (Saint Lucia), the Nature Seekers Group (Trinidad) and the ‘Contrat de baie’ of Fort-de-France (Martinique). These experiences are all cited as success stories in terms of integrated coastal management and as examples to follow. But do they really respond to the objectives of the approach? The proposed analysis grid provides a further reading of the results of these processes and provides more general lessons for the implementation of GIML.