Delta regions are probably the most vulnerable type of coastal environment and their ecosystem services face multiple stresses in the coming decades. These stresses include, amongst others, local drivers due to land subsidence, population growth and urbanisation within the deltas, regional drivers due to changes in catchment management (e.g. upstream land use and dam construction), and global climate change impacts such as sea-level rise.The ecosystem services of river deltas support high population densities, estimated at over 500 million people globally, with particular concentrations in Southern and Eastern Asia and Africa. A large proportion of these people experience extremes of poverty and are severely exposed to vulnerability from environmental and ecological stress and degradation. In areas close to or below the poverty boundary, both subsistence and cash elements of the economy tend to rely disproportionately heavily on ecosystem services which underpin livelihoods.Understanding how to sustainably manage the ecosystem services in delta regions and thus improve health and reduce poverty and vulnerability requires consideration of all these stresses and their complex interaction. This proposal aims to develop methods to understand and characterise the key drivers of change in ecosystem services that affect the environment and economic status in the world's populous deltas. This will be done through analysis of the evolving role of ecosystem services, exploring the implications of changes for the livelihoods of delta residents, and developing management and policy options that will be beneficial now and in the future in the face of the large uncertainties of the next few decades and beyond.The extensive coastal fringe of the Ganges-Brahmaputra-Meghna Delta within Bangladesh has been selected as the pilot study area for this work. This is because Bangladesh is almost entirely located on one of the world's largest and most dynamic deltas. It is characterised by densely populated coastal lowlands with significant poverty, supported to a large extent by natural ecosystems such as the Sunderbahns (the largest mangrove forest in the world). It is under severe development pressure due to many growing cities, eg Khulna and the capital, Dhaka.At present the importance of ecosystems services to poverty and livelihoods is poorly understood. This is due to due to the complexity of interactions between physical drivers, environmental pressures and the human responses to stresses and the resultant impacts on ecosystems. Government policy rarely takes up the ecosystems services perspective and as a result an holistic overview of their value is often overlooked.This project aims to address this gap by providing policy makers with the knowledge and tools to enable them to evaluate the effects of policy decisions on people's livelihoods. This will be done by creating a holistic approach to formally evaluating ecosystems services and poverty in the context of changes such as subsidence and sea level rise, land degradation and population pressure in delta regions. This will be tested and applied in coastal Bangladesh and tested conceptually in other populous deltas.

Mountain landscapes experience sudden and violent geohazards, such as landslides, lake outburst floods, and debris flows. The size and frequency of such events is anticipated to increase due to climate change, enhancing landscape instability. These landscapes are also experiencing rapid population growth, directly exposing people and assets to geohazards, but also exposing them to legacy impacts which manifest after an event and are commonly overlooked and unquantified. A legacy impact of many mountain geohazards is enhanced coarse sediment transport in rivers. This is a problem because sediment travelling as 'bedload' is the primary driver of river channel adjustment. These adjustments affect: 1) flood hazard, by modifying channel bed elevation; 2) the integrity of riparian infrastructure, e.g. hydropower, by blocking intakes and rapidly filling reservoirs, and 3) fluvial ecology, by reorganising channel substrate. It is therefore vital to generate well-constrained knowledge of the pace and manner in which the bedload transport regime evolves in mountain rivers after extreme disturbances. However, due to technical limitations and challenges associated with working in unstable, post-flood landscapes, we have little first-hand information on the behaviour of such systems, which this project aims to address. This new project will consolidate a new international partnership of leading researchers from the UK and India. The team is led by the University of Plymouth, working in close collaboration with the Indian Institute of Technology Roorkee (IITR) and the Wadia Institute of Himalayan Geology (WIHG), the University of Exeter, and Newcastle University. The diverse team bring complementary expertise in geomorphology, hydrology, and environmental sensor networks, and the work would not be possible without the regional knowledge, technical competencies, and field experience of the international partners. The project also features prominent early- and early-to-mid-career researchers in leading roles. Working together we will apply a suite of innovative environmental monitoring and modelling tools to characterise the hydrological and bedload transport regime of the Alaknanda river, Uttarakhand, India, which experienced an extreme debris flow in February 2021 which killed >200 people and triggered enhanced sediment transport as a legacy impact, evidenced through pilot work. To achieve our aim, we will: 1) Develop a new hydrological model of the Alaknanda catchment, enabling us to identify and disentangle the key components of flow (e.g. snowmelt, rainfall). This information will be used to better understand the hydrological drivers of sediment transport; 2) Quantify the grain size characteristics of channel bars using drone- and satellite-based observations and modelling. This information will allow us to explore downstream transitions in grain size through time and examine the influence of the Chamoli event; 3) Deploy innovative, low-cost 'smart' tags to track the motion of cobbles and boulders travelling as bedload. We will supplement these data with measurements of the timing and relative magnitude of bedload transport using low-cost passive seismics. We will effect skills and knowledge transfer in-person via joint fieldwork and discussions at IITR and WIHG), and a regular series of virtual project meetings and seminars. We will publish results in peer-reviewed open-access journals and will produce a technical summary report which we will disseminate to local stakeholders. Project success will lead to future joint funding bids which will appraise the role of hydropower as a disruptor to coarse sediment transport in mountain rivers and explore operational practices that can mitigate the immediate and legacy impacts of extreme floods. In doing so we will further consolidate a wider research network involving regional academics and practitioners, whilst supporting the development of early career researchers in both countries.

SUPERSLUG will push the frontiers of scientific knowledge and technical innovation to reveal new fundamental insights into the legacies of catastrophic sediment-rich flows (SRF) in mountain landscapes, such as landslides, rock-ice avalanches and glacial lake outburst floods. Catastrophic SRFs are hypothesised to become more frequent this century due to climate warming, and often affect vulnerable communities and assets in least developed countries the most. SRFs can entrain, mobilise, and deposit vast quantities of sediment, which can blanket valley floors to depths of tens of metres. The subsequent re-working and transport of these sediments by rivers can generate large-scale and fast-moving 'superslugs', which is a so-called 'legacy' impact of an SRF. Such legacy impacts are poorly understood, mostly due to observational challenges which have persisted for over a hundred years. However, improving our understanding of these impacts is of vital importance: enhanced fluvial transport of sediment following an SRF can affect flood hazard (by altering river channel bed elevation), infrastructure (e.g. by scouring bridge footings and damaging hydropower turbines), and can disrupt water quality, reducing water and energy security in regions that experience increasingly unstable and hazardous hydrological regimes. With SUPERSLUG we seek to encourage a paradigm shift framed around our argument that the landscape legacies of catastrophic SRFs should be quantified in as much detail as an initial event. To do this we will springboard from recent UKRI-funded pilot work by our international team to develop and apply a new multi-method and widely applicable suite of tools for quantifying the geomorphological evolution of SRF-affected catchments over multi-decade timeframes that are relevant for decision makers, in turn generating new insights into the fundamental behaviour, and impacts, of sediment superslugs. We will focus on a ~150 km-long exemplar system in the Indian Himalaya that has recently experienced a catastrophic SRF; the so-called 'Chamoli disaster'. This catchment arguably represents the most data-rich landscape of its type globally and sits within an otherwise extremely data-poor region. To deconstruct the evolution and impacts of sediment superslugs we will implement five work packages which will: (WP1) benchmark the geomorphological and sedimentological evolution of an SRF-affected system in space and time by using drone-derived observations to upscale from local- to catchment-wide observations using satellite remote sensing; (WP2) directly measure bedload motion in SRF-affected river channels using innovative wireless 'smart' cobbles, complemented with passive seismics; (WP3) develop an open-source toolkit for detecting and tracking fine-grained superslugs by leveraging cloud-based (Google Earth Engine) processing of free satellite imagery; and (WP4) integrate our novel observations from WP1-3 to upscale a powerful numerical landscape evolution-hydrodynamic model to simulate superslug mobility and the wider geomorphological evolution of our exemplar catchment. Our calibrated model, which will be a form of 'digital twin', will represent the largest of its kind and we will use it to explore catchment management decisions (e.g. HEP flushing schedules) for mitigating the worst superslug impacts. Underpinning these four WPs is a fifth WP, wherein we will adopt a Theory of Change-based approach for engaging closely with beneficiaries of this new knowledge and associated tools to translate our findings into practical outcomes and impact, including governance and disaster management professionals, hydropower operators and the wider international academic community.

Arsenic in groundwater is causing severe detrimental impacts on human health in the Indian sub-continent. In the Gangetic River Basin, which supports a population of over 500 million people, tens of millions of people are exposed to groundwater arsenic, resulting in more than 15,000 premature deaths each year, as well as enhanced morbidity and reduced economic productivity. Whilst many remediation/mitigation schemes have been implemented to reduce groundwater arsenic exposure, there exist pressures that may partly counteract these efforts. These include: [i] increased reliance on groundwater arising from increased population and affluence coupled with decreased recharge of surface water reservoirs, and [ii] future secular increases in groundwater arsenic which we hypothesise may arise from (a) ingress of surface-derived organic carbon, thought to be strongly implicated in the microbially-mediated biogeochemical processes leading to arsenic mobilisation; or (b) injection of oxygenated waters in managed aquifer recharge (MAR) leading to oxidative dissolution of arsenic-bearing pyrite In this project, we will quantify the vulnerability of shallow urban or rural aquifers to secular increases in groundwater arsenic stimulated by enhanced oxygen or organic carbon supplies. Efficiently and effectively building on existing core research and field and laboratory infrastructure of the highly complementary team of India and UK research and water resource management investigators, this study will combine unique field studies of sedimentologically distinct natural laboratories in the upper, mid and/or lower Ganga/Hooghly as well as contrasting naturally recharging and managed aquifer recharging systems such as river bank filtration (RBF). We will evaluate the biogeochemical processes controlling arsenic mobilisation in key zones, including the hyporheic zone, of surface water-groundwater interactions. We will build upon existing detailed hydrogeological knowledge of the field areas, much built up by the project partners , supplemented by further sampling and analysis of key tracers including CFCs, SF6, tritium, and indicators of provenance, organic biomarkers, including emerging organic contaminants, and redox species ratios. Our developed understanding of these systems will be incorporated into reactive contaminated transport models to (i) facilitate the prediction of groundwater arsenic hazards in the Ganga River Basin over the next 50 years; (ii) inform selection of remediation technologies and approaches, including indirect approaches, such as improving management of near surface urban and rural organic carbon sources. Establishing workable frameworks for considering due diligence, long-term maintenance and sustainability of solutions, social integration of technology using community participatory approaches will be a key element of project outreach and knowledge transfer. The results will inform risk assessment and remediation/mitigation of groundwater vulnerability both elsewhere in India and globally, including in many ODA countries and the UK. We have established a broad and inclusive network of researchers, NGOs, government organisations and other stakeholders with strong interests in mitigating the impacts of human activity on secular increases in the concentration of arsenic and other contaminants in vulnerable groundwaters in India. This network will aim to both transfer knowledge of the hazard, risk and potential remediation/mitigation of these hazards as well as drive for further networking, integration, knowledge transfer and co-funding to better understand the natural and anthropogenic processes controlling these critical public health risks and effective ways to mitigate against them. The partners have substantive and complementary track-records in this area of research and water resource management and will bring significant co-funding to the project, through staff time and/or lab & field infrastructure.

The ecosystem services of deltas often support high population densities - estimated at over 500 million people globally, with important examples in south, south-east and East Asia. As noted in the IPCC AR4 Assessment, deltas are one of the most vulnerable coastal environments and their ecosystem services face multiple stresses in the coming years and decades including (1) local drivers due to development (e.g., urbanisation) within the delta, (2) regional drivers due to changes in catchment management (e.g. dam construction), and (3) global climate change, especially sea-level rise, Understanding how to sustain ecosystem services and reduce poverty and vulnerability in deltaic areas requires consideration of all these stresses and their interaction. This Partnership and Project Development Grant (PPDG) aims to develop a larger proposal that will develop methods to understand and characterise these multiple drivers of change for the Ganges-Brahmaputra delta, explore their implications for poverty and vulnerability of the delta residents, and develop management systems that are resilient in the face of the large uncertainties that exist for the 21st Century. The Ganges-Brahmaputra delta is selected as it is one of the most vulnerable deltas (embracing most of Bangladesh and West Bengal, India), but the methods that are being proposed will be transferable to the management of other delta systems in Asia, Africa and South America. This PPDG integrates across multiple scales of investigation that are often explored independently in different disciplines. Hence, integration of natural science, engineering and social science views is critical and this will be a key step which the PPDG will explore, building on existing experience in the project team such as within the Tyndall Centre for Climate Change Research. The PPDG aims to develop a proposal that integrates all the above issues for both the baseline and future conditions, using poverty or poverty-related outcomes as the key indicators. The proposal will also consider critical intervening factors such as governance and political will in tackling both corruption and the social and economic effects of climate change and other hazards. Poverty outcomes will be considered as a much wider spectrum of wellbeing than just money metrics, which may not be relevant in this setting. We will explore the effect of the scenarios on health, education, social capital and security as well as asset poverty and nutritional levels. Previous research will be developed in order to understand the effects of differing underlying resilience and vulnerability levels among the coastal populations. Particular interest will be focussed on possible thresholds of social capital and material wellbeing, after which the multiple stresses above would have catastrophic effects, including knock on effects such as mass migration. Analysis will occur at various levels - including effects on the individual, the household, the community, the wider area and ultimately the whole nation and delta. The PPDG will develop the research consortium across three countries (UK, Bangladesh and India) and refine the research questions identified to develop a proposal for the December 2010 submission. In particular, it will allow us to embed the research in the Ganges-Brahmaputra to facilitate take-up of the policy recommendations that would emerge if the full proposal was funded.