Identification of phase propagation of water level in tidal river by spectral analysis

Shih, David Ching‐Fang

doi:10.1007/s00477-002-0105-5

Cited by 9 publications

(13 citation statements)

References 10 publications

(12 reference statements)

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“…The 95% confidence interval for the autospectral density function and the non-zero coherence level for cross-spectral density function are also evaluated to pick up significant components in the frequency domain. The basic development of spectral analysis and its expansion to the application in tidal hydrological aspects can be demonstrated in relevant literature (Bendat and Piersol, 1991;Shih et al, 1999Shih et al, , 2000Shih, 2002;Shih and Lin, 2002) …”

Section: Spectral Representation For One-dimensional Confined Groundwmentioning

confidence: 99%

“…From the viewpoint of the application, Equations (9) and (10) are suitable for groundwater flow that encounters different time-dependent water level boundaries at both ends, and Equation (11) (1991). Shih has undertaken a wide range of applications of spectral analysis to identify fluctuation frequency and phase propagation in tidal water level of aquifers and river (Shih et al, 1999Shih, 2002;Shih and Lin, 2002) Autospectral density function is used to detect the stronger signal in time series, whereas cross-spectral density and coherence are measured to identify intensity of specific components between two time-series. The 95% confidence interval for the autospectral density function and the non-zero coherence level for cross-spectral density function are also evaluated to pick up significant components in the frequency domain.…”

Section: Spectral Representation For One-dimensional Confined Groundwmentioning

confidence: 99%

“…Conventional tests and methods for finding aquifer parameters can be found in the literatures (Bear, 1979;Freeze, 1979;Driscoll, 1986;Batu, 1998). For aquifers adjacent to an ocean, river or lake the groundwater table fluctuates with the change of water level in the nearby surface water (Godin, 1972, p. 9;Shih et al, 1999Shih et al, , 2000Shih, 1999bShih, , 2002Shih and Lin, 2002). Such a disturbed groundwater table can be expressed mathematically providing relevant boundary conditions, which can be analysed by the spectral relationships through time-frequency domain of tidal effects.…”

Section: Introductionmentioning

confidence: 98%

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Application of spectral analysis to determine hydraulic diffusivity of a sandy aquifer (Pingtung County, Taiwan)

Shih

Lin

2004

Hydrological Processes

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Abstract:The study demonstrates spectral relationships in the time-frequency domain for one-dimensional groundwater flow in aquifers bounded by fluctuating boundaries. By nature, the solutions of spectral equations are non-linear complex functions. To determine hydraulic diffusivity in the governing equations, it is required that the data are collected from the spectra of water levels at the fluctuating boundaries and observation wells. Hydraulic diffusivity thus can be obtained by an iterative inverse approach. This paper presents an application in Pingtung County of Taiwan to determine the hydraulic diffusivity of a sandy aquifer under confined conditions. Spectral density function of water level obtained from tidal boundaries and observation wells are used to approximate hydraulic diffusivity, which yields an averaged value of 1Ð26 ð 10 6 m 2 /h.

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Section: Spectral Representation For One-dimensional Confined Groundwmentioning

confidence: 99%

Section: Spectral Representation For One-dimensional Confined Groundwmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Application of spectral analysis to determine hydraulic diffusivity of a sandy aquifer (Pingtung County, Taiwan)

Shih

Lin

2004

Hydrological Processes

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“…Many environmental conditions change periodically with time: e.g., the disturbance of waves generated by seasonal wind; ocean tides affected by the interaction between astronomical bodies; the change of groundwater level caused by infiltration from surface water; the groundwater level variation due to the tidal effect of nearby rivers or coasts; and the change of water level in river stages affected by astronomical tidal components from nearby seawater (Shih et al 1999Shih 1999bShih , 2000Shih , 2002Lin 2002, 2004). Wind speed and direction often demonstrate periodic fluctuations which also are subject to the weather system.…”

Section: Introductionmentioning

confidence: 99%

Wind characterization and potential assessment using spectral analysis

Shih

2007

Stoch Environ Res Risk Assess

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This research provides a process for assessment of wind potential using descriptive statistics and spectral analysis. Advantages of spectral analysis are that it not only can identify significant periodic components but also can analyze phase lag and time lag of the significant components for the naturally occurring wind speed time series observed from different locations. On a regional scale, descriptive statistics and spectral analysis can be effectively used to screen out unqualified areas and determine the wind potential of a studied site. In order to demonstrate the method can be effectively used to assess wind potential by wind speed time series, six weather stations in Taiwan are used in this study. The results show that more than half of the observations for Wu-chi station had a mean wind speed of over 4 m/s. The prevailing main wind directions are suggested as being from the North and Northeast for all of the stations. Periodic semi-diurnal and diurnal components are significant for the studied wind speed time series. The results also show that the time lags for the weather stations are one hour or less using Pen-ghu station as a reference.

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“…Further, several authors have also applied the term to estuaries where river flow is of great significance (CHAPPELL;WOODROFFE, 1994;CHUN-YAN;O'DONNELL, 1998;SHIH, 2002;VRIEND, 2003;CARR et al, 2004). Sometimes the term tidal river also appears as a synonym for "riverdominated estuaries" or even for the uppermost part of an estuary, beyond any detectable salinity, but with tidal co-oscillation (COOK et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Tide distortion and attenuation in an Amazonian tidal river

2012

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A B S T R A C TThe present study seeks to evaluate tidal propagation in the Guamá-Capim river system, in the Amazonian region, considering hydrodynamic and geomorphological aspects. Available data sets on fluvial discharge and water level variations were considered, besides several methods of measuring the tides (currents, water levels and discharges) recorded at different stations and in different periods. The main point argued is that fluvial discharge is the key-factor in tidal distortion and tidal bore formation in the system investigated, whereas the low relief of the area would be the main factor contributing to landward tidal incursion. The results show an impressive upward tidal incursion of more than 200 km, including substantial distortion -increasing upstream -of the tidal wave, of which the ebb phase lasts up to 5 hours longer than the flood, including higher flood current velocities as far as 161 km upstream. Generally, only hyposynchronous tidal response was observed. Seasonally, the fluvial discharge varies about 10 times in the Guamá and 4 times in the Capim River. The increase of the fluvial discharge results in an increasing distortion of the tide, besides a weak increase of the attenuation. During high fluvial discharge periods in conjunction with equinoctial tides (e.g. MarchApril), a tidal bore occurs in the system, also increased by the generally low relief. Therefore, the conclusions include: low relief and the distortion related to high fluvial discharges are the main factors controlling tidal propagation along the system and tidal bore formation. Furthermore, the system could be classified as a tidal river, in which massive regional fresh water input results in virtually non-existent salinity throughout the Guamá-Capim system. R E S U M OO presente estudo teve como objetivo investigar a propagação da maré no sistema fluvial Guamá-Capim, na região amazônica, considerando aspectos hidrológicos e geomorfológicos. Os métodos empregados incluem dados históricos de vazões fluviais e níveis d'água, além de medições próprias de maré em diferentes locais e períodos ao longo do sistema. Os principais pontos defendidos no presente trabalho incluem a vazão fluvial como principal fator para a distorção da maré e consequente formação de pororoca no sistema, assim como o baixo relevo da área seria responsável por incremento na incursão da maré para o continente. Os resultados revelam uma penetração da maré de mais de 200 km, ocorrendo também uma forte deformação da maré, se intensificando gradualmente a montante, resultando em uma vazante até 5 horas mais longa que a enchente 161 km a montante, apresentando também velocidades de enchente levemente superiores, incluindo o decaimento contínuo da altura da maré, intensificado a partir desse ponto. Sazonalmente, a vazão fluvial aumenta 10 vezes no rio Guamá e 4 vezes no rio Capim. Durante períodos de alta descarga, combinados com marés equinociais (e.g. março-abril), o fenômeno da pororoca ocorre no sistema, em associação ao baixo relevo da área. Desta for...

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Identification of phase propagation of water level in tidal river by spectral analysis

Cited by 9 publications

References 10 publications

Application of spectral analysis to determine hydraulic diffusivity of a sandy aquifer (Pingtung County, Taiwan)

Application of spectral analysis to determine hydraulic diffusivity of a sandy aquifer (Pingtung County, Taiwan)

Wind characterization and potential assessment using spectral analysis

Tide distortion and attenuation in an Amazonian tidal river

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