Forecasting Risk of Environmental Exacerbation of Dissolved Organic Matter - Building Climate Change Resilience (FREEDOM-BCCR)

Lead Research Organisation: NERC Centre for Ecology and Hydrology
Department Name: Water Resources (Lancaster)

Abstract

The water industry faces intensifying risks to its water treatment systems through rising dissolved organic matter (DOM) concentrations, especially in upland raw water supplies which provide 70% of the UK's drinking water. Rain and meltwater percolating through soils transports DOM to reservoirs. The water industry has to restrict DOM concentrations to minimise taste and odour problems, reduce the potential for algal growth, and prevent the generation of potentially harmful levels of disinfection bi-products, formed from reactions between DOM and chemical disinfectants. DOM concentrations are increasing primarily as a result of an increase in soil organic matter solubility in response to regional reductions in atmospheric pollutants to soils. However, DOM levels in upland waters are also sensitive to variation, and long-term change, in soil temperatures, amounts and intensity of precipitation, the ionic strength of soil waters, the residence time of reservoirs, and seasalt deposition events during winter storms. The influence of these climate-related effects is increasing as organic matter continues to become more soluble. Currently, the primary industry approach to reduce DOM concentrations is the application of coagulant to precipitate the organic matter from the water, but additional filtration may also be required to remove DOM compounds that are less sensitive to this chemical effect. Both processes have a significant carbon footprint and are estimated to have already cost the industry hundreds of millions of pounds through the installation of new equipment where existing infrastructure was no longer able to deal with rising DOM concentrations. There is a pressing need, therefore, to foster a Climate Change Resilience Community that will combine the extensive expertise of the research and industry communities in the UK in order to address this challenge. FREEDOM-BCCR will develop an entirely new approach to understanding, managing, and planning responses to DOM increases in response to climate change. The community will provide the basis of support for decision making and will deliver adaptive (e.g. infrastructure investment) and mitigative (e.g. land-use interventions) approaches with which to build resilience in the upland water supply. We will augment the capability of a prototype Decision Support tool (DSt), developed by the current NERC FREEDOM Project with support from for Scottish Water, by incorporating catchment-specific climate change projections, predictive models and industry knowledge. This development of the FREEDOM DSt will fill critical knowledge gaps in model functionality including climate change impacts on soil and in-reservoir processing of DOM. We will define operational thresholds for DOM quantity and quality across the treatment chain and combine these to produce forecasts, at a UK scale, of DOM risk to drinking water supply.
Proposed activities and respective Work Packages include: generation of UKCP18-based climate change projections using Hydro-JULES downscaled to specific catchments (WP1); Coupling of downscaled climate predictions with catchment and lake/reservoir models to explore the potential impact of climate change in influencing seasonal variation in DOM quantity, quality and vertical distribution in priority intensively monitored drinking water reservoirs and their catchments (WP2); validation of predictions of DOM quantity and quality produced by the FREEDOM DSt, beyond the parameterisation data set from Scottish Water, using hind-casting informed by wider UK industry data (WP3); upscaling application of the FREEDOM-UK DSt to provide predictions of the effects of climate change, land-use change and air pollution scenarios on DOM quantity and quality in other regions of the UK (WP4); and, foster the FREEDOM Climate Change Resilience Community focussing on co-development, application, and show-casing the FREEDOM-UK DSt through a programme of knowledge exchange activities (WP5).

Planned Impact

The overall outcome of the project will be a complete overhaul of the UK water industry's approach to managing the risk of rising DOM, from one currently based on short-term, localised, reactive strategies to a much longer-term, scientifically-informed and business-led approach.
The benefits of the project to industry will be immediate and direct, through access to a co-designed Decision Support tool (DSt), and more gradual through consolidation of newly forged close working relationships through the Climate Change Resilience Community, including NERC research centres, universities and other industry partners. This project will build the foundation of this community, focussing it on addressing the DOM problem. However, we will identify other shared priorities in terms of climate change impacts on water quality including increased nutrient loading leading to heightened risk of cyanobacteria as a result of increased precipitation and temperature, and increased likelihood of metal release from bed sediments as a result of changes in vertical stratification leading to hypoxia. These shared risks will ensure that the outcomes of this project will extend considerably beyond its life and we will work with industry to establish continuation of knowledge sharing and transfer mechanisms, joint studentships, and ongoing research.
The primary scientific output from the project will be the development of a co-designed DSt, underpinned by NERC science and informatics expertise. This will, for the first time, provide UK Water Industry with the capability to respond to: future DOM trajectories and extremes at current/potential future plant locations; changing chemical properties of DOM that affect treatability; the need to plan strategically for catchments at most and least risk of worsening water quality; and the need to implement mitigation measures in catchments where the risk is deemed to be unacceptable and where alternative locations for treatment works are economically unviable, over the coming decades. Industry will be better equipped to conduct strategic planning, for example, identifying when future investments relating to water quality issues may be required. This information will be combined to develop plans and strategies at industry and UK scale to deliver a more climate change resilient UK Water Industry. By informing decisions on where and when to introduce catchment based solutions or new treatment assets, the project could result in savings to the industry, and consequently to water customers, amounting to hundreds of millions of pounds.
All UK water utilities that source water from upland catchments (e.g. United Utilities, Yorkshire Water, Welsh Water, Southwest Water, Northumbrian Water, Northern Ireland Water), as well as Irish Water, face the same threat of rising DOM levels. While the NERC FREEDOM project co-developed the FREEDOM DSt to inform Scottish Water's decision making specifically, this project will scale up co-development to meet wider industry needs to produce a DSt with UK application. Representatives from all interested companies will be invited to the project dissemination meeting, where they will be given the opportunity to become involved in further testing and development of the DSt in ways that may best meet their individual DOM treatment priorities. Promotion by web-based conferencing of the outcomes of the project by the Water Research Foundation will bring the outcomes of the project to an international audience and could go on to influence approaches to managing DOM increases in other parts of the world.

Publications

10 25 50