Effects of Climate Change on Ecologically Sensitive Flows in the Goulburn River Basin, Australia

ABSTRACT

Climate change is expected to substantially modify river flow regimes, yet most climate‐impact studies have focused on changes in streamflow magnitude without explicitly evaluating ecologically sensitive components of the flow regime that underpin environmental‐flow management. This study quantified how projected climate change may alter ecologically sensitive flow characteristics in the regulated Goulburn River, Australia. A calibrated Soil and Water Assessment Tool (SWAT) model was used to simulate daily streamflow using bias‐corrected temperature and precipitation projections from five CMIP5 General Circulation Models (GCMs) under Representative Concentration Pathways (RCP4.5 and RCP8.5). Ecologically sensitive flow metrics representing low‐flow persistence, seasonal flow magnitude, hydrological variability, and high‐flow pulse characteristics were evaluated for two future periods (2030–2050 and 2051–2080) relative to the baseline period (1980–2017). Across multiple climate models and emission scenarios, projected hydrological responses consistently indicated declining low‐flow persistence, changes in seasonal‐flow magnitude, increased hydrological variability and altered high‐flow pulse characteristics, with the magnitude of change generally increasing under the higher‐emission RCP8.5 scenario. Collectively, these responses indicate increasing risks to habitat persistence, hydraulic connectivity and ecological processes that depend on predictable flow regimes. By integrating climate projections, process‐based hydrological modelling, and biologically informed flow metrics, this study moves beyond conventional discharge‐based climate‐impact assessments and provides a transferable framework for evaluating climate‐change impacts on ecologically sensitive components of river flow regimes, thereby supporting adaptive environmental‐flow management in regulated river systems.