Lake Mälaren Ecotwin: challenges and opportunities
Key Ecosystem Service: Drinking Water Supply.
Main objectives of Ecotwin: Short-term forecasts of water temperature and thermal dynamics in the Görväln sub-basin and Long-term water quality simulations to assess how climate change may alter water quality.
Main challenges:
• Climate change and water temperature: Increasing temperatures, changing stratification and altered seasonal patterns may affect water quality and drinking-water treatment.
• Algal blooms and microbiological risks: Warmer temperatures and changed stratification may increase algal blooms, toxins and the occurrence of new microbiological risks.
• Chemical contaminants: PFAS, pharmaceuticals, pesticides and other contaminants from wastewater, industry and diffuse sources pose risks to drinking-water quality.
• NOM and water quality: Climate change may increase NOM concentrations and alter its composition, with potential impacts on drinking-water treatment.
• Pollution sources and pathways: The large catchment contains many potential pollution sources. Better understanding of water origin, flow direction and contaminant transport is needed to identify risks to the drinking-water intakes.
• Complex lake dynamics: The size and complexity of Mälaren make it difficult to predict water flow, stratification and the transport, degradation and retention of contaminants.
• Extreme events: Heavy rainfall and wastewater overflows may increase short-term loads of microbiological and chemical contaminants.
• Saltwater intrusion: Potential future saltwater intrusion from the Baltic Sea may pose an additional risk to freshwater quality.