First, water quality genesis is explained in terms of sources, water pathways and some time scales involved. It goes on to look closer at chemical reactions along water pathways down a landscape catena, using the simple perception of a stream tube.
The river quality outcome is explained in terms of a mix of water fractions with different hydrochemical signatures. Water quality is finally looked at in a 4000-year perspective, explaining some regional similarities and differences in the past.
In looking towards the future, a potential further intensification and expansion in scale is seen as probable in response to driving forces at work, poor mitigation capabilities and the long response times involved.