Complex, large-scale models in water resources engineering are increasingly needed to answer pressing questions on the resilience of coupled human and natural systems to natural hazards – e.g., floods and droughts. Uncertainties abound on the nature and magnitude of future hazards, as well as on the state of the infrastructure, technologies, ecosystems and societies these threats will impact. To address these questions requires the integration of natural and anthropic processes at a range of scales.

This high-stakes modelling challenge presents opportunities for better-informed and more cooperative decision-making from key actors to improve outcomes. A preliminary step towards achieving this is to understand whether model representations of current cooperative arrangements in a water system are fit-for-purpose for resilience assessments. In other words, do they accurately represent vulnerabilities in these systems? This seminar will illustrate how model diagnostic can answer this question by focusing on how commonly employed representations of reservoir operations in large-scale hydrological models can influence our appraisal of water-related extremes. It will use the state-of-the-art representation of reservoirs contained in the Water Balance Model (WBM), a high-profile large-scale hydrological model, applied to a reservoir cascade in the Upper Snake River Basin in the American West. Results demonstrate the importance of understanding where operational coordination plays a crucial role in avoiding or mitigating water-related extremes, and which data should inform it.