A new analytical solution for tide-induced groundwater fluctuations in an unconfined aquifer with a sloping beach

Deriving analytical solutions for tide-induced groundwater fluctuations in unconfined aquifers confronts two problems: (1) As the Boussinesq equation itself contains nonlinear terms, the secular term would be generated in derivation, thus making perturbation solution unable to be deduced to higher order; (2) for aquifers with sloping beaches, the perturbation parameter in existing analytical solution integrating the beach slope and hydrogeological property would be sometimes larger than 1. So the applicatio...