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 has explored 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 has assessed, in the context of real case studies and future scenarios, how risk metrics can be used to inform management decisions and societal preparedness. Enquiry has taken place at a range of different scales, from households and farms to river basins and national scales.
Understanding impacts of drought for critical decisions
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 demonstrates 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 has developed 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, enables 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. The representation of drought impacts in models of species abundance and biodiversity in rivers and wetland ecosystems, such as fens, lowland and upland bogs, was enhanced.
A model of agricultural practices and output has been 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 were analysed through a combination of ‘bottom-up’ study of households and businesses, and consideration of supply chain dependence on drought-sensitive industries.
More frequent droughts will affect land use, water quality and eco-systems
The environmental, economic and social dimensions of water scarcity have been assessed in an integrated way, which enabled 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 enables 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 and have been 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.
Matching presentation of data to stakeholder needs
First-hand experience and ‘collective memory’ of communities affected now, and historically, by water scarcity provide new understandings of the social and cultural dimensions of droughts. Ongoing engagement between the project social scientists, natural scientists and stakeholders helped to ensure that the outputs from the MaRIUS project, including the ‘impacts dashboard’, are matched to their needs and to the evolving policy context. The span of the MaRIUS project was large and covered physical and social science topics including: drought governance, drought options and management, community responses and environmental competency.
Water quality for agriculture, power and the economy
It included climatic aspects of drought and the derivation of a synthetic ‘drought event library’; hydrological responses both on a catchment and national scale; effects on water quality including nutrient concentration in rivers and algal concentrations in reservoirs, and effect of land use change; the ramifications on water resources on the Thames catchment and also nationally.
It included the impact of drought and water scarcity on terrestrial and aquatic ecosystems; agriculture and farming; the economy; and on electricity production.
Drought indices can incorporate various climate and hydrological data within a single indicator that can be used for analysing trends and relaying information to stakeholders, policy makers and the public in a clear format. The drought index value is often presented as a single number, which can be far easier to understand and use than raw data.
A standardized way to categorise drought
In MaRIUS we used the Standardized Precipitation Evapotranspiration Index (SPEI) to determine drought. The SPEI reflects changes in rainfall as well as temperature on water demand through the inclusion of potential evapotranspiration (PET). The SPEI can be calculated for different time periods so that the dynamics of different types of drought (environmental, agricultural, or water supply drought) can be assessed.
Drought onset, severity, and duration are categorised based on the SPEI values, with negative values below a set threshold used to determine drought.
There has been a number of droughts in England over the past 40 years. The most recent notable droughts were 1975-1976, 19891992, 1995-1996, 2004-2006 and 2010-2012.
Over-abstraction to meet the needs of growing populations, agricultural and industrial use, and the effects of climate change are causing multiple challenges in many water-stressed regions, and these are likely to increase in the future. Future However, a study of historical events alone does not provide sufficiently diverse and extreme conditions to study the full range of possible drought conditions and impacts that may occur in the future. As such, MaRIUS has developed an extensive ‘drought event set’ covering the past, present day and future drought conditions. The event set has been used to provide a range of possible weather time series and assess projected changes in drought characteristics for different time-periods that:
• could have occurred in the past (‘Baseline’, 1900-2006)
• might occur in the near future (‘Near Future’, 2020-2049)
• might occur in the far future (‘Far Future’, 2070-2099)
Meaningful outputs for water resource management
The MaRIUS project researchers wanted the project outputs to be as meaningful as possible to both the academic and user communities. In order for the project to realise its aims, and help move the UK towards a risk-based approach to manage water resources with a particular regard for water scarcity, it is important that the project is known about widely, and the researchers could liaise with as many different types as of stakeholders as possible.
A number of events, workshops and symposia were held throughout the project allowing the user community to really get to grips with the research and vice versa. As well as the more traditional routes to engagement MaRIUS embraced media-based solutions to interact with the user community such as podcasts and videos.
Prof Jim Hall, MaRIUS project leader, University of Oxford
Posted October 2019