USING MODELS TO UNDERSTAND NUTRIENTS TRANSFER IN HYDROSYSTEMS

Nutrients and pollutant contamination of freshwater has a strong impact on ecosystem and human health. Contaminants cycling are affected by numerous factors making them difficult processes to study and understand. When adapted to the problem at hand, modelling can help identifying driving factors and assessing contaminants exports in various hydrosystems. The choice of a relevant model will depend on the spatial and temporal scales, the type of ecosystem and data availability, among others. In this presentation, we will be discussing how different models can be chosen and applied to address different issues related to freshwater contamination through three examples. Distributed process-based models can be used to study nitrates dynamics at the groundwater-surface water interface at the reach scale, where a detailed knowledge of flow paths is important. When the environment is very heterogeneous and data collection is difficult (e.g. peatlands) distributed models are difficult to apply. In this case, a conceptual model can help evaluating water balance and dissolved organic carbon exports under different restoration practices. Finally, to identify contamination sources at the watershed scale, a semi distributed model can be used to consider spatial variability while keeping model implementation feasible. This is the case of nutrients exports in Northern Irish watersheds

Léonard is interested in understanding elements fluxes in hydrosystems by using a modelling approach. For many years, he has been involved in environmental research using various models to assess nutrients and contaminants fluxes in wetlands such as peatlands and riparian areas. His work also includes the modelling of contaminant fate at larger scale. His current research is driven by three overarching objectives: i) to identify the controlling factors of contaminant fluxes in wetlands at local scale, ii) to implement these factors in catchment scale models and iii) to assess the role of wetlands in nutrient cycling at large scale.

[Host: Cláudia Carvalho-Santos, Predicting and Managing Ecological Change]

Image credits: Léonard Bernad-Jannin