Improving continental hydrological models for future climate conditions via multi-objective optimisation

Abstract

Australian hydrological characteristics vary across the continent, encompassing diverse climate zones with wet and dry extremes. Moreover, Australia’s hydro-climate is projected to change in response to rising greenhouse gas emissions, where change is now evident from observations. Adaptation to these projected-to-be more intense impacts, requires nationally consistent hydro-climate projections along with an historical context.Calibrating a continental hydrological model against multiple objectives and varying hydroclimate conditions will enable a robust model configuration, thereby improving confidence in projections. We propose using a multi-objective optimisation approach to tune a continental model to represent stores and fluxes across the water cycle, current regional hydroclimes and possible future climate changes. By devising a set of experiments or scenarios which represent plausible projected futures and regional hydrological characteristics, trade-offs between different scenarios are assessed. We show that whilst no one parameter set “fits all” scenarios, this approach can provide a model configuration which “fits most”.