Methods and models to quantify climate-driven changes in groundwater resources

Understanding climate-driven changes in groundwater resources is essential for future water resources management. In this paper, we review methods and models developed to quantify past, present and future climate-driven changes in groundwater resources, and provide an outlook for future research and practice. The Standardised Groundwater level Index (SGI) has been an effective methodology for quantifying historic groundwater resource status across different sites using observed historical data. However, the paucity of groundwater level data means that modelling groundwater levels may also be required. Lumped parameter models such as AquiMod have been shown to be effective at reconstructing groundwater levels at observation boreholes beyond historic records. These models have also been used for seasonal forecasting of groundwater levels and quantifying impacts of climate change. Major challenges remain in linking indicators of groundwater resource status (i.e. levels) with downstream impacts at both the high and low end of the hydrograph. An example of this is provided by estimating impacts of climate change on yields at abstraction boreholes during drought. As well as linking groundwater levels to impacts, future research should explore the full range of the SGI and apply the latest climate model data to AquiMod models. Access to both live groundwater level observations and high performance computing facilities would allow the methods reviewed here to be applied automatically, providing real-time hydrogeological data services