Impacts of water scarcity on the environment, society and the economy are complex. They are profoundly shaped by human choices and trade-offs between competing claims to water. Current practices for management of droughts in the UK have largely evolved from experience. Each drought tests institutions and society in distinctive ways. Yet it is questionable whether this empirical and heuristic approach is fit for purpose in the future, because the past is an incomplete guide to future conditions. The MaRIUS project will introduce and explore a risk-based approach to the management of droughts and water scarcity, drawing upon global experiences and insights from other hazards to society and the environment. MaRIUS will demonstrate, in the context of real case studies and future scenarios, how risk metrics can be used to inform management decisions and societal preparedness. Enquiry will take place at a range of different scales, from households and farms to river basins and national scales. Fine-scale granular analysis is essential for understanding drought impacts. Aggregation to broader scales provides evidence to inform critical decisions in water companies, national governments and agencies. Analysis on a range of timescales will demonstrate the interactions between long-term planning and short-term decision making, and the difference this makes to impacts and risks. Underpinning the risk-based approach to management of water scarcity, the MaRIUS project will develop an integrated suite of models of drought processes and impacts of water scarcity. A new 'event set' of past and possible future hydroclimatic drought conditions will enable extensive testing of drought scenarios. The representation of drought processes in hydrological models at catchment and national scales will be enhanced, enabling improved analysis of drought frequency, duration and severity. Models for assessment of the risks of harmful water quality, in rivers and reservoirs, will be developed. The representation of drought impacts in models of species abundance and biodiversity in rivers and wetland ecosystems, such as fens, lowland and upland bogs, will be enhanced. A model of agricultural practices and output will be used to analyse drought impacts on agriculture and investigate the benefits of preparatory steps that may be taken by farmers. The potential economic losses due to water scarcity will be analysed through a combination of 'bottom-up' study of households and businesses, and consideration of supply chain dependence on drought-sensitive industries. The environmental, economic and social dimensions of water scarcity will be synthesised into a computer visualisation tool (an 'impacts dashboard'). This will enable exploratory analysis of feedbacks between impacts. For example, agricultural land use changes, driven in part by drought frequency, will, in turn, influence water quality and ecosystems. The interdisciplinary analysis will enable comparison of likely outcomes arising from applying both pre-existing drought management arrangements (e.g. restrictions on water use, abstraction limits) and enhanced/innovative management strategies (e.g. use of outlook forecasts, dynamic tariffs). Social science and stakeholder engagement are deeply embedded in the MaRIUS project, which will be framed by a critical analysis of how impacts of droughts and water scarcity are currently understood and managed by key stakeholders, and how this is shaped by institutions, regulation and markets. First-hand experience and 'collective memory' of communities affected now, and historically, by water scarcity will provide new understandings of the social and cultural dimensions of droughts. On-going engagement between the project social scientists, natural scientists and stakeholders will help to ensure that the outputs from the MaRIUS project, including the 'impacts dashboard', are matched to their needs and to the evolving policy context.