Hydropower generation is unusually vulnerable to long-term changes in climate because hydropower generation is directly reliant on rainfall and investment in hydropower generation infrastructure such as dams and turbines is recovered over long periods. Translating climate projections into information that informs business decisions is made more difficult in regions such as Tasmania, where Global Climate Models (GCMs) do a poor job of replicating regional rainfall distributions. Tasmania’s complex topography results in highly heterogeneous rainfall distribution that is poorly replicated by GCMs.

We have adapted data produced by a major dynamical downscaling climate modelling project, Climate Futures for Tasmania (CFT). CFT dynamically downscaled six GCM projections to 2100 under the A2 SRES emissions scenario. The downscaling greatly improved the verisimilitude of model hindcasts, particularly for rainfall. The downscaled climate projections were then run through statewide hydrological models. Hindcasts of hydrological models with climate model inputs showed very good agreement with observed flows. The result is a set of projected inflows to HT’s catchments to 2100.

HT then ran CFT runoff projections through the Hydro Tasmania Systems model TEMSim. TEMSim uses hydrological inputs in conjunction with projected power demand and energy prices to simulate the Hydro Tasmania power generation system. The TEMSim runs translate CFT climate projections into metrics such as storage levels, power generation, and revenue – metrics that can inform the future operation of the Hydro Tasmania system.

Projected changes in runoff were highly heterogeneous: some HT catchments suffered serious declines in inflows, while others showed slight increases.

This paper documents the steps taken to convert GCM projections to information from which business decisions can be made. The impacts of climate change on Hydro Tasmania’s future inflows and generation capacity are presented.