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Dong-sheng Jeng - One of the best experts on this subject based on the ideXlab platform.

  • analytical solution for Tidal propagation in a coupled semi confined phreatic coastal aquifer
    Advances in Water Resources, 2002
    Co-Authors: Dong-sheng Jeng, David Andrew Barry
    Abstract:

    An analytical solution is derived for Tidal fluctuations in a coupled coastal aquifer system consisting of a semi-confined aquifer, a thin semi-permeable layer and a phreatic aquifer. Based on the solution, we study the interactions (via leakage) between the confined and unconfined aquifers in response to tides. The results show that, under certain conditions, leakage from the confined aquifer can affect considerably the Tidal Water table fluctuation in the phreatic aquifer and vice versa. Ignoring these effects could lead to errors in estimating aquifer properties based on Tidal signals.

  • beach Water table fluctuations due to spring neap tides moving boundary effects
    Advances in Water Resources, 2000
    Co-Authors: Ling Li, D A Barry, Frank Stagnitti, J Y Parlange, Dong-sheng Jeng
    Abstract:

    Tidal Water table fluctuations in a coastal aquifer are driven by tides on a moving boundary that varies with the beach slope. One-dimensional models based on the Boussinesq equation are often used to analyse Tidal signals in coastal aquifers. The moving boundary condition hinders analytical solutions to even the linearised Boussinesq equation. This paper presents a new perturbation approach to the problem that maintains the simplicity of the linearised one-dimensional Boussinesq model. Our method involves transforming the Boussinesq equation to an ADE (advection-diffusion equation) with an oscillating velocity. The perturbation method is applied to the propagation of spring-neap tides (a bichromatic Tidal system with the fundamental frequencies wt and wt) in the aquifer. The results demonstrate analytically, for the first time, that the moving boundary induces interactions between the two primary Tidal oscillations, generating a slowly damped Water table fluctuation of frequency omega(1) - omega(2), i.e., the spring-neap Tidal Water table fluctuation. The analytical predictions are found to be consistent with recently published field observations. (C) 2000 Elsevier Science Ltd. All rights reserved.

E. R. Chang - One of the best experts on this subject based on the ideXlab platform.

  • Seed dynamics linked to variability in movement of Tidal Water
    Journal of Vegetation Science, 2007
    Co-Authors: E. R. Chang, R.m. Veeneklaas, Jan P. Bakker
    Abstract:

    Abstract Question: Community structure may be influenced by patterns of dispersed seeds (seed rain) because they contribute to the template of plant community development. We explored factors influencing seed rain in a system dominated by Tidal Water, where direction and magnitude of Water flow are difficult to predict, unlike many other hydrochorous systems where Water flow is directional. We posed three main questions: (1) are patterns in seed rain linked to effects of hydrodynamic variability; (2) do these patterns in seed rain reflect distribution of seed sources and seed production; and (3) what are the implications for the assembly of Tidal communities? Location: Salt marshes on the Wadden island of Schiermonnikoog, The Netherlands. Methods: Species compositions of vegetation, seed rain, seed production and driftlines along a chronosequence of communities were compared. We also studied seed movement by sowing Astroturf® mats with seeds and checking for seeds remaining after a single Tidal inundation...

  • Seed dispersal by small herbivores and Tidal Water: are they important filters in the assembly of salt‐marsh communities?
    Functional Ecology, 2005
    Co-Authors: E. R. Chang, Elena L. Zozaya, Dries P. J. Kuijper, Jan Bakker
    Abstract:

    1. Characteristics of internal seed dispersal (endozoochory) by European Brown Hares were compared with similar dispersal by Brent Geese. Hares deposited more seeds of mid-successional, perennial, high-marsh species than did geese, which deposited more seeds of early successional, annual, low-marsh species. 2. Seed survival and germination of salt-marsh species were higher after ingestion and passage through the digestive system of hares compared with geese. Both hares and geese had a negative effect on the percentage of seeds that germinated in comparison with uningested seeds. 3. Small herbivores (hares and geese) dispersed two orders of magnitude fewer seeds than those dispersed by Tidal Water. 4. Thus these herbivores are not likely to be important filters (constraints) in community assembly at this salt-marsh site on a coastal island in the Netherlands.

Diane Horn - One of the best experts on this subject based on the ideXlab platform.

  • SPRING-NEAP Tidal Water TABLE FLUCTUATIONS in A COASTAL AQUIFER: BEACH SLOPE-SEEPAGE FACE EFFECTS
    Coastal Engineering 2002, 2003
    Co-Authors: Andrew Baird, Diane Horn
    Abstract:

    Spring-neap Tidal Water table fluctuations (SNTWF) are oscillations of a period of approximately 14.79 days. These oscillations propagate much further inland than semi-diurnal and diurnal signals. Previous studies have shown that SNTWF are generated as a result of interactions between semi-diurnal lunar and solar Tidal oscillations, induced by the moving seaward boundary condition. This paper investigates how the formation of seepage faces results in a spring-neap forcing oscillation on the boundary, and how the propagation of this signal in the aquifer also leads to SNTWF.

David Andrew Barry - One of the best experts on this subject based on the ideXlab platform.

  • analytical solution for Tidal propagation in a coupled semi confined phreatic coastal aquifer
    Advances in Water Resources, 2002
    Co-Authors: Dong-sheng Jeng, David Andrew Barry
    Abstract:

    An analytical solution is derived for Tidal fluctuations in a coupled coastal aquifer system consisting of a semi-confined aquifer, a thin semi-permeable layer and a phreatic aquifer. Based on the solution, we study the interactions (via leakage) between the confined and unconfined aquifers in response to tides. The results show that, under certain conditions, leakage from the confined aquifer can affect considerably the Tidal Water table fluctuation in the phreatic aquifer and vice versa. Ignoring these effects could lead to errors in estimating aquifer properties based on Tidal signals.

  • Tide-induced Water table fluctuations in coastal aquifers bounded by rhythmic shorelines
    Journal of Hydraulic Engineering, 2002
    Co-Authors: P. Dong, David Andrew Barry
    Abstract:

    Previous studies on Tidal Water table dynamics in unconfined coastal aquifers have focused on the inland propagation of oceanic tides in the cross-shore direction based on the assumption of a straight coastline. Here, two-dimensional analytical solutions are derived to study the effects of rhythmic coastlines on Tidal Water table fluctuations. The computational results demonstrate that the alongshore variations of the coastline can affect the Water table behavior significantly, especially in areas near the centers of the headland and embayment. With the coastline shape effects ignored, traditional analytical solutions may lead to large errors in predicting coastal Water table fluctuations or in estimating the aquifer's properties based on these signals. The conditions under which the coastline shape needs to be considered are derived from the new analytical solution.

Ling Li - One of the best experts on this subject based on the ideXlab platform.

  • beach Water table fluctuations due to spring neap tides moving boundary effects
    Advances in Water Resources, 2000
    Co-Authors: Ling Li, D A Barry, Frank Stagnitti, J Y Parlange, Dong-sheng Jeng
    Abstract:

    Tidal Water table fluctuations in a coastal aquifer are driven by tides on a moving boundary that varies with the beach slope. One-dimensional models based on the Boussinesq equation are often used to analyse Tidal signals in coastal aquifers. The moving boundary condition hinders analytical solutions to even the linearised Boussinesq equation. This paper presents a new perturbation approach to the problem that maintains the simplicity of the linearised one-dimensional Boussinesq model. Our method involves transforming the Boussinesq equation to an ADE (advection-diffusion equation) with an oscillating velocity. The perturbation method is applied to the propagation of spring-neap tides (a bichromatic Tidal system with the fundamental frequencies wt and wt) in the aquifer. The results demonstrate analytically, for the first time, that the moving boundary induces interactions between the two primary Tidal oscillations, generating a slowly damped Water table fluctuation of frequency omega(1) - omega(2), i.e., the spring-neap Tidal Water table fluctuation. The analytical predictions are found to be consistent with recently published field observations. (C) 2000 Elsevier Science Ltd. All rights reserved.