Jeng, D.-S.Seymour, B. R.Barry, D. A.Li, L.Parlange, J.-Y.2005-12-092005-12-09200510.1016/j.advwatres.2004.05.012https://infoscience.epfl.ch/handle/20.500.14299/221202An existing capillarity correction for free surface groundwater flow as modelled by the Boussinesq equation is re-investigated. Existing solutions, based on the shallow flow expansion, have considered only the zeroth-order approximation. Here, a second-order capillarity correction to tide-induced watertable fluctuations in a coastal aquifer adjacent to a sloping beach is derived. A new definition of the capillarity correction is proposed for small capillary fringes, and a simplified solution is derived. Comparisons of the two models show that the simplified model can be used in most cases. The significant effects of higher-order capillarity corrections on tidal fluctuations in a sloping beach are also demonstrated.Hydraulic conductivitySloping beachCapillary fringeTidal forcingShallow flow expansionSimplified approximationWatertable fluctuationsBeachesDynamicstext::journal::journal article::research article