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Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

How climate-induced warming will interact with future land use changes remains largely unknown. Most studies that have attempted to forecast the effect of climatic changes on hydrology and water quality consider that watershed configuration would not be altered. However, it is likely that land use will continue to evolve over the next decades and that it will have an important influence on future watershed hydrology and water quality. Future climatic changes, combined with land use modifications and land management practices will create complex interactions and feedbacks in aquatic ecosystems.

The long-term objectives of this research program are to examine the sensitivity of river benthic algae (diatoms) to the combined impacts of climatic and land use changes and to evaluate the efficiency of a set of mitigation strategies to maintain the integrity of river ecosystems. To fulfill the objectives of this research program, three methodological approaches are proposed, involving different study designs and temporal and spatial scales. First, the relationships between benthic diatoms and environmental factors (water temperature and flow, sediment and nutrient regimes) will be investigated empirically and at a large spatial scale based on data from a monitoring network extending over more than 800 stream reaches in Eastern Canada. Second, the relationships between benthic diatoms and environmental factors will be tested by means of periphyton experiments in stream mesocosms. Finally, the combined impact of global change scenarios on river benthic diatoms will be investigated using a watershed model (GIBSI), whereby a calibrated hydrological model will be forced with climatic inputs representing several global warming scenarios. In addition to climate simulations, land use and mitigation scenarios will be applied for testing the effects of specific socio-economic measures aimed at reducing point or diffuse nutrient emissions.

Although there is a wide consensus about climatic warming, there is less certainty about the likely impacts on water quality and river ecosystems due to changes in regional precipitation and land use. The results of this research program will enable stakeholders to develop strategies to better adapt to climate change impacts and enhance the ecological integrity of Eastern Canadian rivers. Designs for new farming practices and land use planning will have to incorporate climate change effects, and new operational procedures may be required. Our findings will be useful to define plans for long-term land use zoning that is protective of water quality under a changing climate. The results of this research could be quickly incorporated into practice as part of our collaborations with the stakeholders of 80 agricultural watersheds undergoing algae-based monitoring.