Stable Water Isotope Study of a Mesoscale Precambrian Shield Basin for Improved Model Predictions of Water Quantity and Quality

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The study of the cycling of water through our watersheds is critical to improve our ability to predict the impact of human activities (e.g. urban and agricultural landuse, climate change) on freshwater resources. Regionally, Precambrian shield lakes are showing an increasing number of harmful algae blooms (HABs) with nutrient inputs (e.g phosphorus) and climate conditions likely contributing factors. Computer models are primary tools that help predict future impacts on water resources but their use comes with large uncertainties. Water cycling studies can generate important insights into how water is stored and released to our waterways, improving these models. Recent technology has reduced the cost and improved the ability to analyze water and vapor samples for isotopes of oxygen and hydrogen of the water molecule. Ratios of naturally occurring water isotopes can distinguish the mixture of water sources in streamflow (e.g. snowmelt, groundwater) and the influence of evaporation which provides new evidence of important hydrological processes at scales relevant to watershed management and decision making. Lake Nipissing and the French River are part of an important headwater tributary that flows into Georgian Bay. The lake, and its 13,000 km2 watershed is the source of water to local municipalities and First Nation communities, home to a First Nations fishery and 5% of Ontario's recreational angling, and contributes an estimated $100 million/year to Ontario's economy. Based at Nipissing University's new Watershed Analysis Centre, this research program will apply water isotope technology to improve understanding of water movement in the Sturgeon River-Lake Nipissing-French River (SNF) basin. It will specifically evaluate contributions of snowmelt, groundwater and surface water (e.g. lakes, wetlands, reservoirs) to seasonal streamflow during high and low flows and over several years, capturing inter- and intra-year variability in inputs. The influence of landscape characteristics (geology, soils, topography, natural and human-induced landcover/use) on streamflow generation will be assessed. Findings from the SNF basin will provide new insights into water cycling for Precambrian shield basins with significant influences of anthropogenic activities (urbanization, agricultural activity) and advance research approaches in assessing impacts on water cycling that will be used for improved predictions of the future of our freshwater resources on a broad scale.