SPECTRAL ANALYSIS OF TIDAL FLUCTUATIONS IN GROUND WATER LEVEL1

Authors

  • David Ching-Fang Shih,

    1. Respectively, Ph.D. Program, Department of Civil Engineering, Chungyuan Christian University, P.O. Box 3–7 (INER), Lungtan, 325, Taiwan, R.O.C.; and Associate Professors, Department of Civil Engineering, Chungyuan Christian University, Chungli, Taoyuan, Taiwan, R.O.C. (E-Mail/Shih: cfshth@iner.gov.tw).
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  • Chin-Dee Lee,

    1. Respectively, Ph.D. Program, Department of Civil Engineering, Chungyuan Christian University, P.O. Box 3–7 (INER), Lungtan, 325, Taiwan, R.O.C.; and Associate Professors, Department of Civil Engineering, Chungyuan Christian University, Chungli, Taoyuan, Taiwan, R.O.C. (E-Mail/Shih: cfshth@iner.gov.tw).
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  • Kin-Forie Chiou,

    1. Respectively, Ph.D. Program, Department of Civil Engineering, Chungyuan Christian University, P.O. Box 3–7 (INER), Lungtan, 325, Taiwan, R.O.C.; and Associate Professors, Department of Civil Engineering, Chungyuan Christian University, Chungli, Taoyuan, Taiwan, R.O.C. (E-Mail/Shih: cfshth@iner.gov.tw).
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  • Shi-Ming Tsai

    1. Respectively, Ph.D. Program, Department of Civil Engineering, Chungyuan Christian University, P.O. Box 3–7 (INER), Lungtan, 325, Taiwan, R.O.C.; and Associate Professors, Department of Civil Engineering, Chungyuan Christian University, Chungli, Taoyuan, Taiwan, R.O.C. (E-Mail/Shih: cfshth@iner.gov.tw).
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  • 1

    Paper No. 98113 of the Journal of the American Water Resources Association.Discussions are open until June 1, 2001.

Abstract

ABSTRACT: Water level data at 16 ground water wells and two sea water gauging stations, coupled with barometric measurements in an alluvial plain in the central-west region of Taiwan, are analyzed using spectral analysis in the time and frequency domains. The semi-diurnal component from water level station is observed to be the most noticeable signal while the diurnal component is the less distinct signal recorded at the water level stations. Both semidiurnal and diurnal components are coupled with atmospheric pressure measurements. From the atmospheric pressure data, spectral analysis indicates that both the raw and the pressure adjusted water levels are almost in phase and retain the same amplitude in this area. It implies that the effect of pressure variations is not significant for the sea water and ground water level nearby; the astronomical tidal components, as expected, are the main factor causing fluctuation of ocean water and ground water levels in the Choshuihsi alluvial plain.

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