Multimodel and\nMulticonstituent Scenario Construction\nfor Future Water Quality

Freshwater pollution is, together with climate change,\none of today’s\nmost severe and pervasive threats to the global environment. Comprehensive\nand spatially explicit scenarios covering a wide range of constituents\nfor freshwater quality are currently scarce. In this Global Perspective\npaper, we propose a novel model-based approach for five water quality\nconstituents relevant for human and ecosystem health (nitrogen, biochemical\noxygen demand, anthropogenic chemicals, fecal coliform, and arsenic).\nTo project the driving forces and consequences for emissions and impacts,\na set of common data based on the same assumptions was prepared and\nused in different large-scale water quality models including all relevant\ndemographic, socioeconomic, and cultural changes, as well as threshold\nconcentrations to determine the risk for human and ecosystem health.\nThe analysis portrays the strong links among water quality, socio-economic\ndevelopment, and lifestyle. Internal consistency of assumptions and\ninput data is a prerequisite for constructing comparable scenarios\nusing different models to support targeted policy development.