An integrated catchment modelling for assessment of water quality and its effect on aquatic ecology

The catchment is the appropriate scale to observe and quantify processes related to the water cycle and water quality. In the Karjaanjoki river basin (located in southern Finland) we aim to sustainable agricultural production that does not harm water ecosystems. Indicator species are trout and river pearl mussels. This is one of the few rivers that still has a natural pearl mussel population. Their living conditions have deteriorated, and the population is aging. We used mathematical models to assess the threats of human activity in the catchment area that can influence water quality and thus living conditions of these species. We estimated the change in living conditions from long water quality time series. We created an integrated, process-based model chain (Persist and INCA) to assess different loading scenarios from agricultural practices. Our results show that the agri-environmental measures are sufficient to maintain the current water quality, but more effective measures are needed to improve it. Climate change in particular is putting additional pressure on ecosystems.