Tidal propagation in an oceanic island with sloping beaches

Y.-C Chang,D.-S Jeng,H.-D Yeh

doi:10.5194/hess-14-1341-2010

Abstract

Abstract. In this study, a new analytical solution for describing the tide-induced groundwater fluctuations in oceanic islands with finite length and different slopes of the beaches is developed. Unlike previous solutions, the present solution is not only applicable for a semi-infinite coastal aquifer, but also for an oceanic island with finite length and different sloping beaches. The solution can be used to investigate the effect of higher-order components and beach slopes on the water table fluctuations. The results demonstrate the effect of higher-order components increases with the shallow water parameter or amplitude parameter and the water table level increases as beach slopes decrease.

Highlights

Groundwater near the ocean usually fluctuates with the tides, which will significantly affect the costal processes such as saltwater intrusions, beach sediment transportations, chemical transformations, and biological activities
Dagan (1967) first solved the non-linear governing equation and approximated the solution by an expansion based on a shallow flow approximation
Since the slope of the beach was included in the perturbation parameter in both models, their models may be applicable to a certain range of the beach slopes

Summary

Introduction

Groundwater near the ocean usually fluctuates with the tides, which will significantly affect the costal processes such as saltwater intrusions, beach sediment transportations, chemical transformations, and biological activities. Dagan (1967) first solved the non-linear governing equation and approximated the solution by an expansion based on a shallow flow approximation His solution is applicable when the oscillation of the groundwater motion is small compared with the mean water level. Based on the reason mentioned above, Teo et al (2003) used two perturbation parameters, shallow water parameter and amplitude parameter, to derive a higher-order solution for the tide-induced water table fluctuations in coastal aquifers to a sloping beach They considered the costal aquifers to with infinite extension in horizontal direction; for oceanic islands, the horizontal domain is finite and the beach slopes may be different in both sides of the oceanic island

Objectives

Results

Conclusion