Differences in future recharge estimates due to GCMs, downscaling methods and hydrological models

The impact of climate change upon groundwater has an increasing profile in the literature but there is little guidance on selecting Global Climate Models (GCMs), downscaling methods or hydrological models. This paper quantifies the relative uncertainties inherent in projections of future recharge contributed by multiple GCMs, downscaling methods and hydrological models at three locations across southern Australia. Results highlight that the choice of GCM is the largest source of uncertainty, with a median range between the highest and lowest GCM of 53% of the historical recharge for a given downscaling method and hydrological model. The downscaling method is the next largest source of uncertainty with a median range of 44% and the choice of hydrological model is the source of the least uncertainty with a median range of 24%. These results strongly suggest that impact studies should use multiple GCMs and give careful consideration to the choice of downscaling methods. Citation: Crosbie, R. S., W. R. Dawes, S. P. Charles, F. S. Mpelasoka, S. Aryal, O. Barron, and G. K. Summerell (2011), Differences in future recharge estimates due to GCMs, downscaling methods and hydrological models, Geophys. Res. Lett., 38, L11406, doi:10.1029/2011GL047657.