A New, Catchment-Scale Integrated Water Quality Model of Phosphorus, Dissolved Oxygen, Biochemical Oxygen Demand and Phytoplankton: INCA-Phosphorus Ecology (PEco)

Process-based models are commonly used to design management strategies reduce excessive algal growth and subsequent hypoxia. However, targets typically focus on phosphorus control, under the assumption that successful nutrient reduction will solve hypoxia issues. Algal responses drivers not linear depend additional biotic abiotic controls. In order generate a comprehensive assessment of effectiveness control strategies, independent nutrient, dissolved oxygen (DO), temperature must be coupled, which can increase overall uncertainty. Here, we extend an existing process-based model (INtegrated CAtchment Phosphorus dynamics) include biological demand (BOD), (DO) decay (INCA-PEco). We applied resultant in two eutrophied mesoscale catchments with continental maritime climates. assessed effects regional differences climate land use parameter importance during calibration using generalised sensitivity analysis. successfully reproduced in-stream total (TP), suspended sediment, DO, BOD chlorophyll-a (chl-a) concentrations across range temporal scales, uses regimes. While INCA-PEco is highly parameterized, uncertainty significantly reduced by focusing monitoring efforts just 18 those parameters. Specifically, time could optimized hydrological parameters (base flow, Manning’s n river depth). locations significant inputs diffuse nutrients, e.g., agricultural catchments, detailed data crop uptake rates also important. The remaining provide flexibility user, broaden applicability, maximize its functionality changing climate.