Numerical Solution of Ttidal Induced Fluctuation in an Inhomogeneous Island Aquifer System, and its Comparison with Analytical Solution

Subject Areas : Subjects

Mahdi Asadi-Aghbolaghi ¹ (عضو هیأت علمی گروه مهندسی آب، دانشکده کشاورزی، دانشگاه شهرکرد)
Pari Maleki ² (shahrekord university)
Davood Mohagheghiyan ³ (کارشناس ارشد سازه‌های آبی، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه شهرکرد)
Mohammad Reza Noori-Emamzadeyi ⁴ (عضو هیأت علمی گروه مهندسی آب، دانشکده کشاورزی، دانشگاه شهرکرد)

Received: 2014-08-04 Accepted : 2017-10-20 Published : 2017-08-23

Keywords: Leakage, Unconfined aquifer, Semi-confined aquifer, Aquitard, One dimensional flow,

Abstract :

Tide induced head fluctuation has been considered by many researchers in coastal areas. In this paper, a numerical solution has been developed for an inhomogeneous multi-layered aquifer. This aquifer system comprises an unconfined aquifer on the top, a semi-confined aquifer at the bottom, and an aquitard between them. This coastal aquifer is bounded by coast in longitudinal direction; the coastal boundaries are parallel to each other. The results showed that the amplitude of unconfined aquifer head increases with increase of leakage, however, the amplitude of head fluctuation decreases in the semi-confined aquifer. In addition, the results of analytical solution, the head fluctuation in unconfined aquifer decreases with increase of dimensionless storage coefficient, however, it is almost constant in confined aquifer. Also, increase of dimensionless transmissivity increases the groundwater head fluctuation in both aquifers. Temporal head fluctuation illustrated that time lag has not significant changes, and is greater for semi-confined aquifer with respected to confined aquifer. Comparison between numerical and analytical solutions showed that there is little difference between.

References:

1)        اشجاری،ج. 1388. مکانیسم اثر جزر و مد بر رفتار هیدرولیکی آبخوان ساحلی محبوس.www. ngdir.ir

2)        عطایی آشتیانی، ب. کتابچی، ح. 1389. توسعه الگوریتم بهینه‌سازی جامعه مورچه‌ها به‌صورت تلفیقی با مدل شبیه‌سازی عددی برای مدیریت بهینه آبخوان‌های ساحلی. تحقیقات منابع آب ایران.7(19):1-12

3)       Alcolea , A. Ph Renard. Mariethoz. Bertone F. 2009. Reducing the impact of a desalination plant using stochastic modeling and optimization techniques. Hydrology 365: 275–288.

4)       Ataie-Ashtiani B., R-E Volker. Lockington D-A. 1999. Tidal effects on sea water intrusion in unconfined aquifers. Hydrology. 216: 17–31.

5)       Baird A. Mason T. D. Horn. 1998. Validation of a Boussinesq model of beach ground water behavior. Marine Geology 148: 55-69.

6)       Bear, J. 1979. Hydraulics of groundwater. McGraw-Hill New York. USA. 241.

7)       Ferris J. G. 1951. Cyclic fluctuations of water level as a basis for determining aquifer transmissibility. IAHS Publ. 33: 148–155.

8)       Jeng D.S. L. Li and D.A. Barry 2002. Analytical solution for tidal propagation in a coupled semiconfined/phreatic coastal aquifer. Advances in Water Resources 25: 577–584

9)       J. Jiao, and Z. Tang 1999. An analytical solution of groundwater response to tidal fluctuation in a leaky confined aquifer. water Resource Research. 35: 747–751.

10)   Kim K.Y., H.  Seong, T. Kim, K.H.  Park and N.C. Woo, Y.S. Park, G.W.  Koh,and  W.B. Park 2006. Tidal effects on variations of fresh–saltwater interface and groundwater flow in a multilayered coastal aquifer on a volcanic island (Jeju Island, Korea). Hydrology. 330: 525– 542.

11)   Li, L. D.S. Jeng, and D.A.  Barry 2002. Tidal fluctuations in a leaky confined aquifer: localized effects of anoverlying phreatic aquifer. Hydrology 265: 283–287.    

12)   Parlange, J.Y. and W.  Brutsaert 1987. A capillary correction for free surface flow of 10 groundwater, Water Resour. Res. 23: 805-808.

13)   Philip J.R. 1973. Periodic nonlinear diffusion: An integral relation and its physical 12 consequences. Aust. Phys. 26: 513-519.

14)   Pricket, T.A. 1975. Modeling technicues for groundwater evaluation. Adv. Hidrosci. 10: PP. 564.

15)   Robinson, C., B.  Gibbes and L.  Li 2006. Driving mechanisms for groundwater flow and salt transport in a subterranean estuary. Geophysics Research Letters. 33: L03402.

16)   Robinson, C., L.  Li and D.  Barry 2007. Effect of tidal forcing on a subterranean estuary. Advances in Water Resources. 30 (4): 851-865.

17)   Wang H.F. and Anderson M.P. 1995. Introduction to groundwater modeling finite difference and finite element methods. Academic press, inc. Newyork.