Sea-level rise impacts on groundwater: exploring some misconceptions with simple analytic solutions

Sea-level rise (SLR) causes groundwater salinisation and water-table rise. The impacts these processes can have on water security, agricultural production and infrastructure are becoming widely recognised. However, some misconceptions relating to SLR impacts on groundwater have been observed among students, which may interfere with further learning and the application of science principles to everyday life. These misconceptions include the following: (1) water-table rise will equal SLR; (2) inland movement of the interface causes the rise in the water table under SLR; (3) seawater intrusion (SI) caused by SLR is small compared to SI caused by pumping. These misconceptions are explored with the aid of simple analytic solutions and a Jupyter Notebook. It is shown that: (1) water-table rise is only equal to SLR above the interface under flux-controlled inland boundary conditions; (2) water-table rise under SLR is not caused by SI, but rather is caused by the change in levels at the coastal boundary; (3) SI caused by SLR is a considerable risk, especially under the head-controlled conditions, which will become more common when land is drained to counter the effects of groundwater shoaling.