The project was organized in three work packages (WPs), each with specified milestones and deliverables.
WP1 Climatic drivers of past and future DOM (Lead: Martyn Futter (SLU), co-lead: Pirkko Kortelainen (Syke))
In this WP, we will compile data on DOC, water colour and other easily-measured features of DOM quality including UV-VIS (Ultraviolet / Visible) absorbance spectra from drinking water reservoirs and monitoring databases in the Nordic countries, in addition to potential drivers such as climate, hydrology, sulphur and nitrogen deposition and land use. Trends and drivers of changing DOM quality and quantity will be assessed and compared among regions. DOM quality and quantity will be simulated using process-based models in order to predict regional effects of a changing climate on DOM and water colour across Fennoscandia.
This WP will deliver inputs to WP2 and WP3 in the form of model predictions of future DOM quantity and quality under climate change, for specified Nordic catchments and upscaled to Fennoscandia.
WP2 DOM quality, characterization, reactivity and treatability (Lead: Lars Tranvik (UU), co-lead: Helge Liltvedt (NIVA))
Here, we will focus on climate-related effects on DOM quality. DOM quality in raw water affects choice for optimal drinking water treatment. DOM quality affects microbial growth and formation of biofilms in pipelines and other surfaces. These properties will vary both between localities, depending on hydrology and catchment properties as well as water residence time, but also seasonally within localities depending on microbial activity, solar exposure, lake-water mixing regimes . We will focus on the main drinking water sources for Helsinki (Lake Päijänne), Stockholm (Lake Mälaren) and Oslo (Lake Maridalsvannet), hereafter referred to as PMM, and on several other well-studied lakes and rivers that are also included in other WPs.
This WP will deliver insights on the effectiveness of drinking water treatment for removal of DOM in raw water with relevance for process optimization, and specifically applied to major raw water sources of Helsinki, Stockholm and Oslo. Special attention will be paid to effects of changing climate and discharge on DOM quality and treatability.
WP3 Adaptation to climate change (Lead: Helge Liltvedt (NIVA), co-lead: Martin Forsius (Syke))
The drinking water supply sector in Norway, Sweden and Finland will need to adapt to changes in raw water quality related to higher DOM. The cost of drinking water provision is directly linked to the quality of its raw water input, which is itself affected by climate and upstream land use patterns. Changes in raw water quality need to be counteracted by adaptation in operation of the water treatment plants, for example, by use of more or different chemicals, or by longer or more intensive UV radiation. In some cases entirely new treatment steps will be necessary to remove the increased DOM (and colour). Adaptation of treatment may be solved by prescribing engineering solutions. However, that might not be the best solution; a more integrated set of solutions combining upscaling of treatment plants, new treatment technology, along with improved control systems and source protection measures to improve raw water quality in close collaboration with long-term planning of the entire supply system are more likely to have an overall beneficial long term effect. The water supply system represents a major investment in infrastructure and a valuable asset for Nordic municipalities. Replacement costs are considerably higher than costs of rehabilitation and good maintenance. Proper management in the face of adaptation to climate change is therefore important.
This WP will synthesize the knowledge collected in WP1 and WP2, adapted to the needs of stakeholders and society. An overview of current and emerging technologies for removal of DOM will be supplied, in addition to an economic valuation of adaptation of water treatment to changing DOM quality and quantity. Risk assessment for adaptation to climate-change induced changes in drinking water quality for Oslo and Helsinki will be produced.