Turbidity currents are the volumetrically most import process for sediment transport on our planet. A single submarine flow can transport ten times the annual sediment flux from all of the world's rivers, and they form the largest sediment accumulations on Earth (submarine fans). These flows break strategically important seafloor cable networks that carry > 95% of global data traffic, including the internet and financial markets, and threaten expensive seabed infrastructure used to recover oil and gas. Ancient flows form many deepwater subsurface oil and gas reservoirs in locations worldwide. It is sobering to note quite how few direct measurements we have from submarine flows in action, which is a stark contrast to other major sediment transport processes such as rivers. Sediment concentration is the most fundamental parameter for documenting what turbidity currents are, and it has never been measured for flows that reach submarine fans. How then do we know what type of flow to model in flume tanks, or which assumptions to use to formulate numerical or analytical models? There is a compelling need to monitor flows directly if we are to make step changes in understanding. The flows evolve significantly, such that source to sink data is needed, and we need to monitor flows in different settings because their character can vary significantly. This project will coordinate and pump-prime international efforts to monitor turbidity currents in action. Work will be focussed around key 'test sites' that capture the main types of flows and triggers. The objective is to build up complete source-to-sink information at key sites, rather than producing more incomplete datasets in disparate locations. Test sites are chosen where flows are known to be active - occurring on annual or shorter time scale, where previous work provides a basis for future projects, and where there is access to suitable infrastructure (e.g. vessels). The initial test sites include turbidity current systems fed by rivers, where the river enters marine or freshwater, and where plunging ('hyperpycnal') river floods are common or absent. They also include locations that produce powerful flows that reach the deep ocean and build submarine fans. The project is novel because there has been no comparable network established for monitoring turbidity currents Numerical and laboratory modelling will also be needed to understand the significance of the field observations, and our aim is also to engage modellers in the design and analysis of monitoring datasets. This work will also help to test the validity of various types of model. We will collect sediment cores and seismic data to study the longer term evolution of systems, and the more infrequent types of flow. Understanding how deposits are linked to flows is important for outcrop and subsurface oil and gas reservoir geologists. This proposal is timely because of recent efforts to develop novel technology for monitoring flows that hold great promise. This suite of new technology is needed because turbidity currents can be extremely powerful (up to 20 m/s) and destroy sensors placed on traditional moorings on the seafloor. This includes new sensors, new ways of placing those sensors above active flows or in near-bed layers, and new ways of recovering data via autonomous gliders. Key preliminary data are lacking in some test sites, such as detailed bathymetric base-maps or seismic datasets. Our final objective is to fill in key gaps in 'site-survey' data to allow larger-scale monitoring projects to be submitted in the future. This project will add considerable value to an existing NERC Grant to monitor flows in Monterey Canyon in 2014-2017, and a NERC Industry Fellowship hosted by submarine cable operators. Talling is PI for two NERC Standard Grants, a NERC Industry Fellowship and NERC Research Programme Consortium award. He is also part of a NERC Centre, and thus fulfils all four criteria for the scheme.

Turbidity currents are the volumetrically most import process for sediment transport on our planet. A single submarine flow can transport ten times the annual sediment flux from all of the world's rivers, and they form the largest sediment accumulations on Earth (submarine fans). These flows break strategically important seafloor cable networks that carry > 95% of global data traffic, including the internet and financial markets, and threaten expensive seabed infrastructure used to recover oil and gas. Ancient flows form many deepwater subsurface oil and gas reservoirs in locations worldwide. It is sobering to note quite how few direct measurements we have from submarine flows in action, which is a stark contrast to other major sediment transport processes such as rivers. Sediment concentration is the most fundamental parameter for documenting what turbidity currents are, and it has never been measured for flows that reach submarine fans. How then do we know what type of flow to model in flume tanks, or which assumptions to use to formulate numerical or analytical models? There is a compelling need to monitor flows directly if we are to make step changes in understanding. The flows evolve significantly, such that source to sink data is needed, and we need to monitor flows in different settings because their character can vary significantly. This project will coordinate and pump-prime international efforts to monitor turbidity currents in action. Work will be focussed around key 'test sites' that capture the main types of flows and triggers. The objective is to build up complete source-to-sink information at key sites, rather than producing more incomplete datasets in disparate locations. Test sites are chosen where flows are known to be active - occurring on annual or shorter time scale, where previous work provides a basis for future projects, and where there is access to suitable infrastructure (e.g. vessels). The initial test sites include turbidity current systems fed by rivers, where the river enters marine or freshwater, and where plunging ('hyperpycnal') river floods are common or absent. They also include locations that produce powerful flows that reach the deep ocean and build submarine fans. The project is novel because there has been no comparable network established for monitoring turbidity currents Numerical and laboratory modelling will also be needed to understand the significance of the field observations, and our aim is also to engage modellers in the design and analysis of monitoring datasets. This work will also help to test the validity of various types of model. We will collect sediment cores and seismic data to study the longer term evolution of systems, and the more infrequent types of flow. Understanding how deposits are linked to flows is important for outcrop and subsurface oil and gas reservoir geologists. This proposal is timely because of recent efforts to develop novel technology for monitoring flows that hold great promise. This suite of new technology is needed because turbidity currents can be extremely powerful (up to 20 m/s) and destroy sensors placed on traditional moorings on the seafloor. This includes new sensors, new ways of placing those sensors above active flows or in near-bed layers, and new ways of recovering data via autonomous gliders. Key preliminary data are lacking in some test sites, such as detailed bathymetric base-maps or seismic datasets. Our final objective is to fill in key gaps in 'site-survey' data to allow larger-scale monitoring projects to be submitted in the future. This project will add considerable value to an existing NERC Grant to monitor flows in Monterey Canyon in 2014-2017, and a NERC Industry Fellowship hosted by submarine cable operators. Talling is PI for two NERC Standard Grants, a NERC Industry Fellowship and NERC Research Programme Consortium award. He is also part of a NERC Centre, and thus fulfils all four criteria for the scheme.

All rivers across the globe that exit to the ocean contain a zone, which can be 100s of kilometres long, which is transitional between river and tidal environments (termed here the Tidally-Influenced Fluvial Zone, or TIFZ). This zone is one of the most complex environments on the surface of the Earth because it is an area where both river flow and tidal currents are significant, and these competing forces vary daily, seasonally and annually. These regions are important to mankind and form some of the areas of highest population density: they are strategically important in the present day because these zones are at the interface of competing demands for shipping, aquaculture, land reclamation and nature conservation. Thus in order to better maintain, manage and protect these fragile zones, we must understand how and why these regions change and what factors control such change. Additionally, the sediments of ancient TIFZs may contain significant volumes of hydrocarbons which are increasingly the target for many energy companies. For example, the Athabasca oil sands form the largest petroleum deposit on Earth and these bitumen tars are locked up with ancient TIFZ sediments. Understanding the internal nature of such TIFZ sediments is thus of paramount importance when attempting to extract the maximum quantity of oil (or gas) from such ancient hydrocarbon reservoirs - we need to know what controls the geometry and internal characteristics of these reservoirs, and thus better plan efficient and maximal hydrocarbon extraction strategies. Thus all of these interests in both modern and ancient TIFZ environments depend on a detailed knowledge of the fluid flows in these areas, how such flows transport their sediment and critically how the form (or morphology) of these environments changes through time. However, due to the extraordinary challenges of working in such a complex and dynamic environment, few high-resolution, spatially-representative, field datasets exist and remarkably little work has been undertaken on the diagnostic internal sedimentary structure of such TIFZ deposits. Additionally, whilst there has been progress on the mathematical modelling of estuarine flow and sediment transport, these models remain largely untested. There is therefore a pressing need to link the processes and deposits of the TIFZ through an integrated study of their flow, morphology and sediment movement to quantify the key processes and how these are represented within the subsurface sedimentary record. This proposal outlines an integrated field and mathematical modelling study that seeks to achieve a step-change in our understanding of the TIFZ, using the very latest techniques in field survey and mathematical modelling. These techniques will yield unrivalled high-resolution datasets of bathymetry, flow, sediment transport and sedimentary structure that will then be used to construct and validate new numerical models of the TIFZ. This will ultimately allow evaluation of key unknowns with respect to the TIFZ, such as how such environments evolve under changing scenarios of tidal and fluvial contributions associated with sea-level change, and whether it is possible to differentiate between 'fluvial' and 'tidally' influenced deposits. Such results will transform our understanding of how such TIFZ zones behave in modern environments and critically how these changes may be recognized within ancient sedimentary successions.

Salt marshes exist around the globe on low-lying, low gradient coastal fringes. Amongst providing many services to society (valued at around £1,500 per hectare per year), they are valued for their ability to protect coasts from the erosive force of waves and tides, even during extreme storm surge events. They are, however, nationally and globally in decline. In the UK, the area of salt marsh reduced by 13% between 1945 and 2010 (from 37,300 to 32,500 ha). This loss has not been compensated for through marsh restoration efforts (only 1,320 ha created by 2012). There is high uncertainty as to how these natural coastal protection features (or their artificially restored or re-created equivalents) will respond to the combined effects of future changes in sea level and possible changes in the magnitude and/or frequency of storms. The grass/shrub covered surfaces of salt marshes appear remarkably resistant to storm impact. Given sufficient sediment supply, they can also 'grow' vertically to track rising sea levels. The loss of marsh area over time is therefore more often due to a landward retreat of their most seaward margin or the lateral widening off the tidal channels that drain them. These boundaries are often undercut, with marsh material loosened and removed by tidal currents and waves. Such retreat may reach several metres per year and is of great concern to coastal engineers, planners, and managers, relying on the 'storm buffering' function of these environments. We know little about the force required to 'cut into' salt marsh material (the 'substrate'). The substrate itself is composed of sediment laid down over time by the tides, alongside organic materials resulting from plant growth and invertebrates living in the soil. Its resistance to wave or tidal forces therefore varies within and between marshes. But this resistance has not, so far, been measured in a way that allows coastal engineers to take it into account when predicting the impact of future environmental scenarios (e.g. greater water depths and stronger tidal currents or waves). In this project, we will sample and analyse in detail the substrate of a more sandy (Warton, Morecambe Bay) and a more muddy (Dengie, Essex) marsh, as well as of two restored marshes (two East coast managed realignment sites) and their adjacent natural equivalents. We will determine what these substrates are composed of, how this varies between and within each of these marshes and how it affects the resistance of the marsh substrate to wave and tidal forces. State-of-the-art technology (unmanned aerial vehicles (UAVs) or 'drones') and the latest satellite products will then allow us to produce a map of the physical marsh vulnerability of marsh systems, both in their entirety and within marsh, to these types of forces. Coastal planners, engineers, and managers will benefit through being able to better predict marsh loss into the future and design suitable preventative measures. Anyone watching our three-part documentary short film series will benefit through a better understanding of the scientific methods we use. The global community already using existing satellite products built into web-based tools for assessing the coastal protection function of salt marshes will benefit by being able to access predictions of the resistance to wave/tide erosion that we will build into those tools.

The transport of sediments is a key process in the global geological cycle, a cornerstone of aquatic ecosystems and has a multi-billion pound impact on agricultural, industrial and urban, flood- and erosion-risk hazards. Understanding and being able to predict the stability of gravel river beds is important for multiple reasons: changes in river bed shape will change the channel capacity and thus affect flood risk; the bed stability affects the amount of sediment that can be moved by the flow, which will have impacts on the downstream channel morphology and dynamics; the river bed is a habitat for many species, and thus changes in the river bed will have implications for the river ecosystem; and in order to manage and restore rivers effectively, channels need to be designed with a known level of stability. However, current ability to predict sediment entrainment and thus river bed stability is limited by our understanding of the factors that affect sediment movement. Grain size is typically accounted for, but other factors such as sediment structure (the way in which individual sediment grains are packed together in 3D) and the role of fine sediments in cementing grains together are not. Furthermore, these factors vary spatially across the bed of a river, producing a spatial pattern of areas that are more or less easily entrained, i.e. a template of erodibility. We hypothesis that this spatial pattern of erodibility plays an important role in controlling both the shape of the river bed, and how this shape changes under different flow conditions. We will test this hypothesis by quantifying, for the first time, the development of 3D sediment structure in both a field and a laboratory environment using high energy CT-scanning. These data will allow us to identify causal relationships between the different controls and sediment structure. The application of this technique to large numbers of samples from both field and laboratory settings will provide a significant and unique dataset for understanding the structure and production of 3D bed sediments. Using an existing theoretical framework, we will use the data from both the flume and field data to produce relationships that can be used to predict sediment structure, and consequently the erodibility of the bed, from the controlling factors of sediment input and flow. This relationship will be implemented within a numerical modelling framework in which we will upscale from the field and flume to represent additional range of channel and flow conditions. We will work with end-users to ensure that the new knowledge is transferred effectively into guidance for policy and operational activity within the river management community.