Groundwater response to tidal fluctuation and rainfall in a coastal aquifer

This paper presents an analytical solution generated by linearizing the one-dimensional non-linear Boussinesq equation to characterize the variation of groundwater level induced by tidal waves and rainfall in a coastal unconfined sloping aquifer. The area of the coastal aquifer is divided into 2 zones - the coastal zone of rainfall and the inland zone of non-rainfall. The derivation of the solution is based on the Dupuit-Forchheimer assumptions of a wide range of problems in unconfined groundwater flow and the analytical solutions of coastal and inland water tables of both zones are obtained. The results indicate that the effects of the bottom slope of the aquifer and the beach slope on the groundwater fluctuation are substantial in the unconfined aquifer. Large rainfall intensity with tidal waves will enhance the fluctuation significantly, but less effect on the fluctuation is found for the cases of steeper sloping bottom under the same rainfall condition. (C) 2014 Elsevier B.V. All rights reserved.