Long term time series modelling of groundwater heads for assessment of climate change impact

Given the changes in precipitation and evaporation over the past 60 years and the expectation that the climate will continue to change, it is to be expected that groundwater heads will change in such a way that land use, infrastructure, ecology and water availability will be strongly impacted if the current water management is continued.
In order to assess the impact, the response of the groundwater system to precipitation and evaporation needs to be determined. Challenges are the inclusion of slow responses and capturing extremes. Responses in the order of decades often are not considered in groundwater modelling due to calibration periods shorter than 10 years and the time scale of impacts to be simulated. Capturing the level of high extremes is important for e.g. groundwater flooding. Capturing the level and duration of low extremes is needed for water availability and subsidence.
A case study from the Netherlands will be presented in which predictions until 2100 are made based on the climate scenarios from the Royal Dutch Meteorological Institute (KNMI) in combination with weather data and measured groundwater heads from a polder area in Friesland.