Assumptions & limitations for saline intrusion

The following assumptions and limitations should be considered when consulting the maps on salinisation via groundwater:

• The data have been calculated based on the effect of sea level rise. Consequences of climate change, including changes in precipitation, temperature and river discharges, have not been incorporated.
• The calculations are based on the following points of departure: current water management will continue as is. Rivers that are currently open in nature will remain open and keep pace with the rising sea level. Rivers and lakes that are currently dammed will remain dammed, whilst their water level management will remain unchanged.
• In order to factor in the slow reaction of rising saltier groundwater, the sea level scenarios have been linked to the RCP4.5 IPCC-scenario.

River discharge volumes play a key role in the calculations of saline intrusion via river estuaries. For that reason, several choices have been made to specify river discharges, that should be considered when using the data:

• The calculation models are based on the current water distribution strategy.
• Riverbeds and river morphologies remain constant. If the riverbed should rise along with the rising sea level, saline intrusion will be less than calculated.
• The calculations are based on a constant river water salt content, taking account, however, of different salt contents at different discharge volumes.
• Two engineering structures (the Haringvliet sluices and Hagestein weir) have a major impact on the discharge distribution in the Rhine-Meuse estuary, but their operating functionality at different scenarios of sea level rise have not been considered. In all model calculations, the Haringvliet sluices are closed.