Impacts of climate change on hydrological parameters in northeastern Avalon Basins using the IHACRES model

This study evaluates the performance of the conceptual rainfall–runoff model IHACRES for simulating streamflow and assessing climate change impacts in five Northeastern Avalon watersheds under SSP245 and SSP585 scenarios for 2040–2065. The model was calibrated and evaluated using observed precipitation, temperature, and discharge data, applying statistical performance metrics (NSE, RMSE, R², PBIAS) and a split-sample approach. A Flow Duration Curve (FDC) analysis complemented daily and monthly diagnostics to examine model performance across different flow regimes. Future streamflow simulations were conducted using bias-adjusted climate projections from the CanESM5 model of CMIP6. The IHACRES model achieved acceptable simulation accuracy in the Leary’s Brook, Waterford, and Virginia watersheds (monthly NSE > 0.5; PBIAS ±10%), while performance was weaker in Raymond and Northeast Pond, where lake regulation affected rainfall–runoff responsiveness. Winters are projected to experience higher flows associated with warmer and wetter conditions, while summers show greater variability and potential decreases depending on basin characteristics and scenario. The study’s novelty lies in combining FDC-based evaluation with a Python-weighted multi-model approach to refine climate inputs, improving simulation robustness. This research represents the first climate-informed, multi-basin IHACRES application for Newfoundland and offers insights to support regional water management and climate adaptation strategies addressing both flood and drought risks.