National scale climate change impact assessment – investigating long-term variations in the climate change signal for groundwater levels across geologies and aquifers

The effect of climate change on groundwater system is still not extensively understood. Studies often focuses on changes in recharge to the groundwater system but rarely investigate the resulting impacts on hydraulic head levels especially the spatial distribution of the change across larger domains.

Only few countries in the world have access to a detailed national hydrological model, and fewer still have done nationwide climate change assessments. This study applies a combination of the newest updated national hydrological model for the entire Denmark (the DK-model 2019, http://dk.vandmodel.dk/in-english/) and 20 climate model projections from the Euro-Cordex project (Jacob et al., 2014) for the RCP4.5 and the RCP8.5 emission scenario (4 and 16 runs respectively). The climate dataset are bias-corrected for the Danish area using double Gamma distribution-based scaling for temperature and precipitation (Pasten-Zapata et al., 2019).

This large dataset is used to evaluate the distribution of the magnitude and direction of changes with special focus on the phreatic surface and the main water-bearing groundwater layers for drinking water consumption in Denmark. The spatial variations in the near-surface impact signal across the entire country is also analyzed, as different Quaternary geology is represented from sandy layers in the west to moraine clay tills in the east and marine sand and clay to the north. The climate dataset is a successive time series from 1970ties to the end of the century and thus also enables an analysis of long-term changes in the state of the groundwater system and aquifers. 

 

 

Jacob, D., Petersen, J., Eggert, B., Alias, A., Christensen, O. B., Bouwer, L. M., Braun, A., Colette, A., Déqué, M., Georgievski, G., Georgopoulou, E., Gobiet, A., Menut, L., Nikulin, G., Haensler, A., Hempelmann, N., Jones, C., Keuler, K., Kovats, S., Kröner, N., Kotlarski, S., Kriegsmann, A., Martin, E., van Meijgaard, E., Moseley, C., Pfeifer, S., Preuschmann, S., Radermacher, C., Radtke, K., Rechid, D., Rounsevell, M., Samuelsson, P., Somot, S., Soussana, J.-F., Teichmann, C., Valentini, R., Vautard, R., Weber, B., and Yiou, P.: EURO-CORDEX: new high-resolution climate change projections for European impact research, Regional Environmental Change, 14, 563-578, 10.1007/s10113-013-0499-2, 2014.

Pasten-Zapata, E., Sonnenborg, T. O., and Refsgaard, J. C.: Climate change: Sources of uncertainty in precipitation and temperature projections for Denmark, Geological Survey of Denmark and Greenland Bulletin 43, e2019430102-2019430101-e2019430102-2019430106, https://doi.org/10.34194/GEUSB-201943-01-02 2019.