Groundwater response to dual tidal fluctuations in a peninsula or an elongated island
Article first published online: 26 SEP 2012
Copyright © 2012 John Wiley & Sons, Ltd.
International Journal for Numerical and Analytical Methods in Geomechanics
Volume 37, Issue 15, pages 2456–2470, 25 October 2013
How to Cite
Wang, Q., Zhan, H. and Tang, Z. (2013), Groundwater response to dual tidal fluctuations in a peninsula or an elongated island. Int. J. Numer. Anal. Meth. Geomech., 37: 2456–2470. doi: 10.1002/nag.2144
- Issue published online: 11 SEP 2013
- Article first published online: 26 SEP 2012
- Manuscript Accepted: 31 JUL 2012
- Manuscript Revised: 11 MAY 2012
- Manuscript Received: 29 AUG 2011
- coastal aquifer;
- transient groundwater flow;
- Laplace transform;
Groundwater flow in a peninsula or an elongated island is influenced by tidal fluctuations on both sides of the peninsula or island, which is named as dual tidal fluctuations. In this study, semianalytical solutions of transient groundwater flow in response to dual tidal fluctuations in an aquifer–aquitard system were presented for cases with and without the aquitard storage. These solutions were first derived using the Laplace transform and subsequently computed by the Fourier series numerical inverse Laplace transform. The derived solutions were found to agree very well with the results of numerical simulations by MODFLOW. The solution ignoring the aquitard storage approached the quasi-steady state solution quickly when the mean sea level initial condition was used. The solutions with and without the aquitard storage were nearly the same at the early time and were separated from each other during the intermediate time, and the difference of solutions became constant at late time for small aquifer/aquitard storativity ratio and large tidal frequency. The propagation bias, which is the departure from the theoretical ratio of tidal attenuation to tidal lag, was enhanced not only with increase of the dimensionless specific leakage (aquitard/aquifer hydraulic conductance ratio) but also with decrease of the aquifer/aquitard storativity ratio and with the increase of the dimensionless tidal frequency. The solution with the aquitard storage was more sensitive to these three parameters. The newly developed solutions were capable of handling realistic initial conditions that might be approximated by piecewise linear functions. Copyright © 2012 John Wiley & Sons, Ltd.