The beds of most alluvial river channels are not flat, but comprise a series of undulating sedimentary accumulations termed 'bedforms' that include ripples and dunes. These bedforms exist over a range of scales, and are constantly moving and changing their shape, size and form in response to changes in flow discharge. These bedforms are the primary roughness elements that provide resistance to the water flow. The response of bedforms to a changing discharge is therefore critical for predicting flood inundation levels. Changes in flow discharge are more rapid than changes in the bedforms, such that bedforms are commonly out of equilibrium with the flow. This is very important as the vast majority of our bed-phase diagrams (stability field predictors that relate flow velocity and sediment size to the bedform types likely to be present), morphodynamic simulations, and numerical model predictions assume simplified bed morphologies that are based on equilibrium bed states and constant discharges. Consequently, many feedbacks within our models and predictions are either ignored or highly simplified. This is a significant shortcoming as it is these models that are used, especially in more populated and urban areas, to meet demands on safety against flooding, navigation, hydropower, aggregate mining and water supply. The astute management of these rivers is paramount, putting high demands on accuracy in design, implementation and monitoring. If such models are to be improved, then new fundamental understanding is required of the processes that underlie the dynamics of bedform adjustment to unsteady flow and ways of integrating such knowledge into modelling practice. As a step towards this goal, there is a need to link hydraulic controls, the response of sediment transport processes and morphological adjustment, and the changes in form drag and bed resistance to a range of unsteady flows. Once established, these relations can be used to help improve our understanding of these dynamic processes and predict better the river stage for a set of given discharge changes. This project will delineate these processes using a combination of (i) novel laboratory investigations in a state-of-the-art flume that will quantify the flow structure and sediment transport over fixed and mobile beds as stage varies, (ii) intense fieldwork during flood events in the Mississippi River that will map and quantify changes in bed morphology, flow structure and sediment transport, and (iii) development and application of an innovative numerical model of unsteady flow over a deformable 3D boundary. This modelling work will ensure that the results are generic and have a wider appeal, notably in the improvement of models that provide flood predictions and inform environmental management decisions. All data and output will be made freely available via scientific outlets but also through public dissemination events, the internet and via a GoogleEarth based XML interface.

Rocks in the upper crust of the Earth are often porous, with the pores and cracks filled with fluids like water, oil or gas. Forces acting on these rocks, arising from the weight of the overlying rocks and from plate tectonics, deform the grains and pores and cracks, changing their shape and volume. This deformation occurs before any fracturing or faulting, and is described by a theory called poroelasticity. This theory states that the orientations of the cracks and pores, where the pore fluid resides, exerts a major control on the response of the rock to stress. Fluid-filled parallel cracks occur in patterns around major earthquake prone faults, and these produce a much stronger response than random orientations of cracks or pores. Therefore, the poroelastic properties of rocks are important for our ability to forecast earthquakes on big faults and induced seismicity from human activities such as fluid injection in boreholes for CO2 sequestration or hydraulic fracturing (or 'fracking'). The poroelastic properties of rocks have been measured in the laboratory but all the data measured to date has been under a very special stress condition that probably does not exist in the Earth. Conventional triaxial stress (CTS) applies a vertical stress on a cylindrical rock sample, and then a constant pressure around the sides. We know that the stresses in the Earth vary in all directions, a condition known as true triaxial stress (TTS). And yet we have no poroelastic data from measurements under this stress state. A newly commissioned apparatus at UCL has been specifically designed to deform fluid saturated rock samples under true triaxial stresses and thus provide a unique and timely opportunity to address the core scientific issues: there are no published measurements of poroelastic coefficients measured under TTS and we urgently need better data to constrain better models of seismic hazard. Recent work by the investigators has shown that TTS produces significantly different patterns and densities of cracks in comparison to similar loading paths under CTS: TTS produces predominantly aligned parallel cracks, whereas CTS tends to produce radial cracks. We must systematically collect these data under the most likely in situ stress conditions within the crust - true triaxial stress - and we can use these new data to make tested, more robust, models of seismic hazard. Recent work has shown how important crack fabrics are for the fluid pressurisation, and potential weakening, of earthquake-prone faults. Arrays of fault parallel cracks around seismically active faults could produce a short-term fluid pressure change along the fault equal to the fault normal stress, allowing the fault to slip in an earthquake. This has potentially massive consequences assessing earthquake risk on major faults. Married with the increasing demand for accurate predictions of directional variations in stress and strain in the subsurface (e.g. deviated drilling for geothermal energy or hydraulic fracturing), this adds urgency to our rationale. We will produce open source software from our research, freely available to other scientists, engineers and the wider public. The first tool, currently being tested, will quantify the three-dimensional (3D) patterns of pores and cracks, including their orientations, sizes and shapes. The statistical distributions of these features will be quantified and used to help predict the poroelastic properties using the published theory. The second tool will use our newly measured poroelastic data to revise published models of earthquake triggering. The inclusion of poroelastic deformation in the current models is mixed with the frictional behaviour, but these are very different physical phenomena. Our new code will combine our previous work on the spatial variations of elastic properties around fault zones with the new laboratory measurements to make more robust forecasts of triggered earthquake hazard.

This project addresses how environmental change affects the movement of sediment through rivers and into our oceans. Understanding the movement of suspended sediment is important because it is a vector for nutrients and pollutants, and because sediment also creates floodplains and nourishes deltas and beaches, affording resilience to coastal zones. To develop our understanding of sediment flows, we will quantify recent variations (1985-present) in sediment loads for every river on the planet with a width greater than 90 metres. We will also project how these river sediment loads will change into the future. These goals have not previously been possible to achieve because direct measurements of sediment transport through rivers have only ever been made on very few (<10% globally) rivers. We are proposing to avoid this difficulty by using a 35+ years of archive of freely available satellite imagery. Specifically, we will use the cloud-based Google Earth Engine to automatically analyse each satellite image for its surface reflectance, which will enable us to estimate the concentration of sediment suspended near the surface of rivers. In conjunction with other methods that characterise the flow and the mixing of suspended sediment through the water column, these new estimates of surface Suspended Sediment Concentration (SSC) will be used to calculate the total movement of suspended sediment through rivers. We then analyse our new database (which, with a five orders of magnitude gain in spatial resolution relative to the current state-of-the-art, will be unprecedented in its size and global coverage) of suspended sediment transport using novel Machine Learning techniques, within a Bayesian Network framework. This analysis will allow us to link our estimates of sediment transport to their environmental controls (such as climate, geology, damming, terrain), with the scale of the empirical analysis enabling a step-change to be obtained in our understanding of the factors driving sediment movement through the world's rivers. In turn, this will allow us to build a reliable model of sediment movement, which we will apply to provide a comprehensive set of future projections of sediment movement across Earth to the oceans. Such future projections are vital because the Earth's surface is undergoing a phase of unprecedented change (e.g., through climate change, damming, deforestation, urbanisation, etc) that will likely drive large transitions in sediment flux, with major and wide reaching potential impacts on coastal and delta systems and populations. Importantly, we will not just quantify the scale and trajectories of change, but we will also identify how the relative contributions of anthropogenic, climatic and land cover processes drive these shifts into the future. This will allow us to address fundamental science questions relating to the movement of sediment through Earth's rivers to our oceans, such as: 1. What is the total contemporary sediment flux from the continents to the oceans, and how does this total vary spatially and seasonally? 2. What is the relative influence of climate, land use and anthropogenic activities in governing suspended sediment flux and how have these roles changed? 3. How do physiographic characteristics (area, relief, connectivity, etc.) amplify or dampen sediment flux response to external (climate, land use, damming, etc) drivers of change and thus condition the overall response, evolution and trajectory of sediment flux in different parts of the world? 4. To what extent is the flux of sediment driven by extreme runoff generating events (e.g. Tropical Cyclones) versus more common, lower magnitude events? How will projected changes in storm frequency and magnitude affect the world's sediment fluxes in the future? 5. How will the global flux of sediment to the oceans change over the course of the 21st century under a range of plausible future environmental change scenarios?

Sea and society interact most strongly at the coast where communities both benefit from and are threatened by the marine environment. Coastal flooding was the second highest risk after pandemic flu on the UK government's risk register in 2017. Over 1.8 million homes are at risk of coastal flooding and erosion in England alone. Extreme events already have very significant impacts at the coast, with the damage due to coastal flooding during the winter 2013/14 in excess of £500 million, and direct economic impacts exceeding £260 million per year on average. Coastal hazards will be increasing over the next century primarily driven by unavoidable sea level rise. At the same time, the UK is committed to reach net zero carbon emissions by 2050. It is therefore essential to ensure that UK coasts are managed so that coastal protection is resilient to future climate and the net zero ambition is achieved. Protecting the coast by maintaining hard 'grey' defences in all locations currently planned is unlikely to be cost-effective. Sustainable coastal management and adaptation will therefore require a broader range of actions, and greater use of softer 'green' solutions that work with nature, are multifunctional, and can deliver additional benefits. Examples already exist and include managed realignment, restoration of coastal habitats, and sand mega-nourishments. However, the uptake of green solutions remains patchy. According to the Committee on Climate Change, the uptake of managed realignment is five times too slow to meet the stated 2030 target. Reasons are complex and span the whole human-environment system. Nature-based solutions often lack support from public opinion and meet social resistance. Despite removing long-term commitment to hard defences, the economic justification for green approaches remains uncertain due to high upfront costs, difficulty in valuing the multiple co-benefits offered, and uncertainties inherent to future environmental and socio-economic projections. The frameworks used to support present day coastal management and policy making (e.g. Shoreline Management Plans) do not provide comprehensive and consistent approaches to resolve these issues. Consequences are that the effectiveness of these policy approaches is reduced. Delivering sustainable management of UK coasts will therefore require new frameworks that embrace the whole complex human-environment system and provide thorough scientific underpinning to determine how different value systems interact with decision making, how climate change will impact coastal ecosystem services, and how decision support tools can combine multiple uncertainties. Co-Opt will deliver a new integrated and interdisciplinary system-based framework that will effectively support the required transition from hard 'grey' defences to softer 'green' solutions in coastal and shoreline management. This framework will combine for the first time a conceptual representation of the complex coastal socio-ecological system, quantitative valuation of coastal ecosystem services under a changing climate, and the characterisation of how social perceptions and values influence both previous elements. Our new framework will be demonstrated for four case studies in the UK in collaboration with national, regional, and local stakeholders. This will provide a scalable and adaptive solution to support coastal management and policy development. Co-Opt has been co-designed with project partners essential to the implementation and delivery of coastal and shoreline management (e.g. Environment Agency, Natural Resources Wales, NatureScot, coastal groups) and will address their specific needs including development of thorough cost-benefit analyses and recommendations for action plans when preferred policy changes. Co-Opt will further benefit the broad coastal science base by supporting more integrated and interdisciplinary characterisation of the complex coastal human-environment system.

Submarine sediment density flows ("turbidity currents") and rivers on land are volumetrically the most important processes for moving sediment across our planet. However, submarine flows are more episodic and are typically more violent (with speeds of up to 20m/s) than river floods. Moreover, a single submarine flow is capable of transporting ten times the annual sediment load from all of the world's rivers combined. Submarine flows are important because they produce many of the world's most extensive and voluminous sedimentary deposits, both on the modern sea floor and in the ancient rock record, but also because they can break seafloor cables that now carry over 95% of global data traffic (that underpin our daily lives through the internet and financial markets). Ancient submarine flows created subsurface rock sequences that contain many of our largest oil and gas reserves. Submarine flows carve canyons, which are deeper than the Grand Canyon, through processes that are still poorly understood, and flows within canyons play a key role in supplying organic carbon and nutrients to benthic ecosystem (that include important diversity hotspots) in the deep sea. The most remarkable aspect of submarine density flows is how difficult they are to monitor directly, and how few observations we presently have of such flows in action. This paucity of direct observation provides a stark contrast to the information available for other major sediment transport processes. Changes in the frontal speed of submarine flows have been measured in just five locations, mainly through indirect evidence provided by the timing of sequential underwater cable breaks. Their vertical velocity profile has only ever been measured in three locations and never with sampling rates more frequent than one per hour. No flow has been monitored along its full path, which is of key importance because flows evolve considerably in character along that path. To produce a fundamental step-change in our understanding of submarine flows we need to directly monitor active flows along their entire flow path. Until this is achieved, our understanding of the flow character and its spatial evolution will remain limited. This project will provide by far the most detailed monitoring data yet collected for submarine flows: be the first that places constraints on both dilute and dense near-bed flow components, be the first data set that spans the full flow path, and be the first data set to link measurements of flow processes and the resulting deposit character in such an environment. We aim to conduct a large-scale collaborative program to document and understand sediment transport processes occurring within Monterey Canyon offshore California during an 18-month period in 2014-16, in collaboration with the Monterey Bay Aquarium Research Institute (MBARI) and US Geological Survey (USGS). Such international collaboration is essential for spreading the cost of this ambitious work. MBARI are providing the project with access to a series of innovative tools for monitoring flows that MBARI have designed, built and field tested over the last decade; a contribution worth over $10 Million. This includes aBenthic Instrument Nodes for their Monterey Ocean Observing System that will provide the first high frequency (every 2 to 30 seconds rather than hourly) measurements of 3D velocity, temperature, salinity and density profiles from such flows. MBARI also provide access to the research vessels and ROVs necessary for equipment deployment and servicing during this 18 month period, as MBARI is located at the head of the canyon. MBARI and USGS will place further monitoring equipment in the canyon as part of the project that is worth a further $1.5 Million. Moreover, the MBARI and USGS bear the risk for the loss of all of their equipment. NERC bears a small fraction of the total cost and risk for this unique field experiment, which therefore represents exceptional value for money.