Climate change threatens water availability in regulated rivers, including for freshwater ecology which rely on environmental flows. However, in large basins, the impacts of climate change depend not only on the differences in spatial patterns of climate variables (temperature, precipitation, etc.), but also on the hydrologic responses and water management policies of specific rivers. Interactions between different water allocation frameworks, catchment biogeographical conditions and river geomorphology mean regulated rivers can respond very differently to climate change. In such large basins, spatial and temporal patterns of impacts will affect the sequencing, prioritisation, and viability of different climate adaptation options at various spatial scales.
This work seeks to understand patterns of climate change vulnerabilities for environmental flow objectives in the Goulburn, Campaspe, and Loddon rivers in northern Victoria. Such patterns may be disparate given orders of magnitude difference in flow volumes, and distinct hydroclimate regimes between the rivers. Vulnerability is identified using stress-testing techniques, which begins with a sensitivity test of environmental outcomes (from projections of mechanistic ecological models) to plausible changes in future climate (simulated by stochastic climate and flow inputs through a parsimonious water resource model).
Given the identified vulnerabilities, several adaptation strategies are assessed for their ability to provide robust benefits to ecological outcomes across uncertain future climate change. Robust adaptation strategies are those that delivery benefits despite assumptions around particular climate projections or emissions scenarios. Here, adaptation strategies are mostly be focused on managing water at a whole-of-basin scale, as distinct from the current management focus toward individual river outcomes. This may be particularly important for river systems with degrees of ecological and hydrological connectivity.