In recent years there has been growing concern about the impact of diffuse source pollution on river, estuarine and coastal water quality and particularly with regard to non-compliance of bathing waters. Climate change, and particularly more intense storms in the bathing season, has led to increased compliance failure of bathing waters, e.g. last summer saw widely publicised beach failure occurrences at Amroth and Rhyl. Hydro-environmental impact assessment modelling studies, regularly undertaken by specialist consulting environmental companies, are generally regarded as having two fundamental shortcomings in model simulations, which can lead to erromneous environmental impact assessment outcomes. These shortcomings will be addressed in this project and include: (i) improving the computational linking of catchment, river and estuarine-coastal models to ensure momentum and mass conservation across the link boundary, and (ii) improving the kinetic decay process representation in deterministic models, to include the impact of salinity, irradiance, turbidity and suspended sediment levels. The main aim of this research project will therefore be to develop and validate linked hydro-environmental deterministic models to predict improved fluxes and concentration levels of faecal bacterial from catchment to coast, using dynamic decay rates related to a range of primary variables. This main objective will be achieved by: (i) setting up linked catchment, river and estuary-coastal models to predict flow and solute transport processes from Cloud to Coast; (ii) linking these models through an Open MI system and refining the link to include momentum conservation; (iii) extending the Cardiff Research Centre's Severn and Ribble river basin models to include catchments, (iv) developing and testing the Severn model against scaled laboratory model data for conservative tracer measurements, obtained using an idealised catchment-river-estuary physical model at Cardiff University, (v) undertaking a detailed analysis of earlier field studies (undertaken by the main supervisor and Professor David Kay, Aberystwyth) on the impact of turbidity and sediment adsorption on bacterial levels in the Severn estuary, with the aim of developing new formulations linking bacterial concentration levels with: salinity, irradiance, turbidity and suspended sediment), (vi) including the new formulations for bacterial decay (in the form of T90 values) in the linked models for river and estuary-coastal systems and to investigate the sensitivity of the receiving water concentration levels to these parameters, and (vii) studying briefly the effects of various renewable energy structures in the Severn estuary (including the Severn Barrage) on the receiving water faecal bacterial levels, particularly in terms of establishing the impact of the new linking methodology and the dynamic decay rates on the predicted concentration levels. The outcomes from this study will be published in journal and conference papers and presented in talks and lectures on the Centre's activities relating to marine renewable energy and particularly for the Severn estuary.

Sea level rise is now acknowledged as a real threat to our coastal towns and cities. In addition, global climate changes may lead to increasing frequency and severity of storms. As a result the value of the UK's assets at risk from flooding by the sea have significantly increased. The current UK coastal flood defences, which have typically been designed to withstand storm events with a return period of 50-100 years, may now be inadequate to protect the coastal areas under threat. To improve the design of future coastal defences requires a better understanding of the linkages between atmosphere, ocean and seabed; as well as improved quantification of the inherent uncertainties in the predictions. This joint research proposal between the Universities of Plymouth, Bristol and Liverpool, aims to develop a robust and integrated 'Cloud-to-Coast' modelling framework which will include the complex interactions between atmosphere, ocean and coastal flood and erosion, so that the flood risk in the coastal areas from the extreme events, such as severe storms, can be accurately predicted and assessed. The project will use various existing proven computer programmes together with necessary further developments to provide information on meteorological conditions under severe storms, the associated surge and wave conditions, as well as detailed transformation of wind and waves from the offshore to areas close to shoreline in order to predict coastal flood and erosion due to wave overtopping and scour. The main work of the project includes: 1) integration of the large-scale high-resolution weather models for predicting the atmospheric pressure and wind field, the regional and local scale process models for wave transformation from offshore to nearshore, and the local coastal models for predicting wave overtopping and scour near the coastal defence structures; 2) validation of the integrated modelling system with extensive field datasets; and 3) application of the modelling system to investigate uncertainties by creating ensembles of possible future storm events. The major output of the project will be a well-developed and validated modelling system which can be used as a useful tool for coastal engineers and coastal zone managers to assess the possible flood risk in coastal areas.

Project Summary: Nature-based coastal defence solutions have increasingly been recognized as more sustainable alternatives to conventional hard engineering approaches against climate change. These include using wetlands, mangroves, coral and oyster reefs as a buffer zone, which can attenuate waves and, in a regime of moderate sea level rise, the sediment trapping in such zones can keep pace with sea level. Wetlands and mangroves are regions in which more salt-tolerant species exist, which can protect freshwater species behind them. Nature-based defences have been deployed in the USA, Netherlands and UK and also in some parts of China, with varying degrees of success. In deltas undergoing fast urbanisation, applying nature-based solutions can lead to competition for space with other land uses, e.g. land-reclamation. For optimised management, the question of how much space is required by nature-based solutions must be addressed. However, our current knowledge of the size-dependent defence-value and resilience of different ecosystems is insufficient. Additionally, we lack full understanding of the methods needed for ecosystem creation for coastal defence, as previous restoration efforts have suffered low success rates. The current proposal aims to develop process-based understanding and predictive models of ecosystem size requirements and how to create ecosystems for coastal defence, using the world's largest urban area, the Pearl River Delta (PRD) in China, as a model system. Delta-scale mangrove area monitoring and hydrodynamic modelling will be conducted to study recent wetland area changes and estimate the optimisation of ecosystem spaces for defence, under contrasting scenarios of climate change and land-reclamation. This large-scaled study will also provide underpinning boundary conditions for local-scale experiments and modelling. A set of experiments using novel instruments will be conducted to improve our insights into the processes influencing mangrove resilience and propagation. Innovative measures of using dredged materials and oyster reefs to facilitate mangrove establishment will also be tested experimentally. Local-scale models will incorporate the new experimental knowledge to predict mangrove bio-geomorphic dynamics and provide guidelines for management. The developed models and knowledge will be directly applied in the design of a pilot eco-dike project due to be constructed, in collaboration with our project partners. We will consider how to address resilient urban planning and management, in terms of combining spatial planning and disaster management by optimising land use, institutions and mechanisms for more sustainable urbanisation, exploring eco-dynamic design options to provide opportunities for nature as part of the urban development processes. Summary of the UK applicants' contribution to the project: The UK applicants will lead Work Task 1: Wetland area monitoring/hydrodynamic modelling. This work task will provide an over-view of the bio-physical conditions, including the morphological and land-use aspects of the PRD and its regional setting, for the present day, and under future climate projections of sea level and storms. The UK team will implement a high resolution unstructured-grid model (FVCOM) for the Pearl River Delta (PRD) for hydrodynamics, waves and sediment transport which will provide the interface between the larger scale atmospheric and oceanic boundary conditions and the smaller-scale process studies and ecosystem modelling to be carried out by our Dutch and Chinese partners. This model, together with regional sea level projections, will be used to provide quantitative scenarios for the local area ecological modelling.

The problem of hydraulic resistance in wall-bounded flows remains among the hottest research topics in theoretical and applied fluid mechanics in spite of also being one of the most long-standing hydraulic problems. Researchers continue exploring a wide variety of empirical and conceptual approaches to resolve this problem, particularly focusing on the parameterisation of the bed friction that controls water levels, flood inundation extent, flow rates, depths, and water velocities. The approach currently used for quantifying bed friction is mostly empirical and thus should be considered the weakest component of otherwise quite sophisticated design and modelling methodologies. Despite world-wide efforts to advance capabilities for prediction and control of water levels in free surface flows, especially during flood events, hydraulic engineers still use empirical or semi-empirical relationships for 'roughness' or 'friction' factors. These resistance coefficients subsume the combined effects of complex hydrodynamic processes in simple forms making them convenient for practical applications. There is a general agreement that these resistance coefficients depend on parameters of the flow, bed material, bed and channel forms, and in-stream and bank vegetation. Although the quantitative form of this dependence has been targeted by several generations of hydraulicians, available relationships linking the resistance coefficients to flow and roughness parameters are still largely empirical rather than theoretically justified. As a result, the level of uncertainties of hydraulic models of overland flows, canals, waterways, rivers, and estuaries remains high, often exceeding 20-40%. The central goal of the project is therefore to develop advanced predictive capabilities for quantification of hydraulic resistance in rough-bed open-channel flows and propose a methodology for incorporation of the theoretical and physical insights from this study into applied hydraulic models that are most relevant to the end-users. To achieve this goal, the project team will build a rigorous theoretical framework to explicitly reveal contributions to the total bed friction from viscous, turbulent, and form-induced stresses, secondary currents, non-uniformity, and unsteadiness, and link these contributions to the physics of the flow. This theoretical analysis will underpin sophisticated laboratory experiments in Aberdeen and Large Eddy Simulation numerical studies in Cardiff to clarify the nature of bed friction in open-channel flows, refine the definitions of the roughness regimes, and identify and quantify the contributions to the overall friction from the dominant friction-generated mechanisms. The combination of the theoretical analysis with laboratory and numerical studies will lead to the generalised relationships for the friction coefficients suitable for applied hydraulic models. The examples of benefits that the proposed research will bring include significantly reduced uncertainties in predictions of water levels and flood inundation extent; better urban planning and new design philosophies based on friction control/reduction aptitudes that this research intends to develop (e.g., 'friction-reduced' urban planning as part of 'green cities' concept and more efficient drainage systems); and improved stream restoration design and implementation, among many others. The theoretical and methodological developments of the project will be also applicable, in addition to water engineering, to other areas such as aerospace and mechanical engineering, where drag control studies are particularly important and continue to grow. The interdisciplinary fields of overland flow and soil erosion, biomimetics, and ecosystems (both terrestrial and aquatic), represent other examples where the outcomes of this project can be directly employed.

Infrastructure is vital for society - for economic growth and quality of life. Existing infrastructure is rapidly deteriorating, the rate of which will accelerate with increasing pressures from climate change and population growth, and the condition of the large majority of assets is unknown. Stewardship of infrastructure to ensure it continuously performs its function will be a colossal challenge for asset owners and operators. The performance of new infrastructure assets must be monitored throughout their life-cycle because they are being designed and constructed to withstand largely unknown future conditions. The UK must be better prepared to face these grand challenges by exploiting technology to increase understanding of asset deterioration and improve decision making and asset management. This research is central to EPSRC's priority area of Engineering for Sustainability and Resilience. The goal is to transform geotechnical asset management by developing new, low-cost, autonomous sensing technologies for condition appraisal and real-time communication of deterioration. This new approach will sense Acoustic Emission (AE) generated by geotechnical assets. AE is generated in soil bodies and soil-structure systems (SB&SSS) by deformation, and has been proven to propagate many tens - even hundreds - of metres along structural elements. This presents an exciting opportunity that has never been exploited before: to develop autonomous sensing systems that can be distributed across structural elements (e.g. buried pipes, pile foundations, retaining walls, tunnel linings, rail track) to listen to AE - analogous to a stethoscope being used to listen to a patient's heartbeat - and provide information on the health of infrastructure in real-time. The idea to use AE sensing to monitor geotechnical assets in this way is novel - it is expected to lead to a disruptive advance in monitoring capability and revolutionise infrastructure stewardship. AE has the potential to increase our understanding of how assets are deteriorating, which could lead to improved design approaches, and to extract more information about asset condition than existing techniques: not only deformation behaviour, but also, for example, changes in stress states, transitions from pre- to post-peak shear strength, and using correlation techniques it will be possible to locate the source of AE to target maintenance and remediation activities. AE sensing will also provide real-time warnings which will enable safety-critical decisions to be made to reduce damages and lives lost as a result of geotechnical asset failures. The number of asset monitoring locations required per unit length to achieve sufficient spatial resolution will be less than other monitoring techniques, and significantly lower cost. Piezoelectric transducers, which sense the AE, are now being developed at costs as low as a few tens of pence per sensor - this recent technological advance makes this research timely. AE sensors could be installed during construction to monitor condition throughout the life-cycle of new-build assets (e.g. HS2), and retrofitted to existing, ageing assets. This will be the most fundamental and ambitious investigation into the understanding of AE generated by SB&SSS yet attempted. The findings will mark a major leap forward in scientific understanding and our ability to exploit AE in novel asset health monitoring systems. The fellowship aims to develop robust diagnostic frameworks and analytics to interpret AE generated by geotechnical assets. This will be achieved using a powerful set of complementary element and large-scale experiments. The outcomes will be demonstrated to end-users and plans will be developed with collaborators for: full-scale field testing with in-service assets to demonstrate performance and benefits in intended applications and environments; and implementation in commercial products that could have significant societal and economic impact.