1st Edition

Modeling morphodynamic evolution in alluvial estuaries

By Mick van der Wegen Copyright 2011
    206 Pages
    by CRC Press

    206 Pages
    by CRC Press

    The main objective of this research is to investigate the governing processes and characteristics that drive morphodynamic evolution in alluvial estuaries by application of a process-based numerical model (Delft3D). It is of utmost importance to understand estuarine processes so that impact of human interference (like dredging and land reclamation) and long-term changes (like sea level rise) can be evaluated.

    The research addresses a number of cases ranging from an rectangular basins to real estuaries like the Western Scheldt in the Netherlands or San Pablo Bay in California. The more schematized approach allow to study morphodynamic evolution over several millennia under constant forcing and answers more fundamental questions related to conditions of equilibrium and related time scales. The more realistic cases give insight into the skill of the approach in predicting decadal morphodynamic developments. More processes are included to mimic realistic conditions and model results are compared to bathymetric measurements over the last century.

    The research shows that the modeling approach is good capable of describing stable morphodynamic calculations over a timescale of millennia with patterns similar to patterns observed in reality. Additionally, the approach shows that it is possible to predict decadal morphodynamic developments in real estuaries with significant skill.

    1. Framework for morphodynamic modeling in alluvial estuaries
    1.1. Introduction
    1.1.1. What is estuarine morphodynamics?
    1.1.2. Relevance and research scope
    1.1.3. Observations and empirical research
    1.1.4. The concept of an 'ideal' estuary
    1.2. Morphodynamic modeling techniques
    1.2.1. Physical scale modeling
    1.2.2. Framework for mathematical approaches
    1.2.3. Morphodynamic scaling techniques
    1.2.4. Dimensions in modeling
    1.3. Aim of the study
    1.3.1. Main objective
    1.3.2. Research questions
    1.3.3. Relevance
    1.3.4. Approach
    1.4. Model description (Delft3D)
    1.4.1. Hydrodynamic model
    1.4.2. Sedmiment transport formulation
    1.4.3. Morphodynamic model
    1.4.4. Numerical aspects
    1.4.5. Brier Skill Score (BSS)
    2. Schematized 1D and 2D model results and Western Scheldt data
    2.1. Introduction
    2.1.1. Earlier research
    2.1.2. Aim of the study
    2.2. Model geometry and configuration
    2.3. Results
    2.3.1. 1D-schematization
    2.3.2. 2D-schematization
    2.3.3. Pattern formation
    2.3.4. Morphological wavelength
    2.3.5. Longitudinal profile
    2.3.6. Cumulative transports
    2.3.7. Comparison to empirical relationships
    2.3.8. Hypsometry and intertidal area
    2.3.9. Ebb and flood dominance
    2.4. Discussion
    2.4.1. Two time scales
    2.4.2. Pattern formation
    2.4.3. Comparison of 1D and 2D longitudinal profiles
    2.4.4. Tide residual sediment transport
    2.4.5. Boundary condition
    2.4.6. Morphological update scheme
    2.5. Conclusions and further research
    3. Bank erosion and energydissipation in an idealized tidel embayment
    3.1. Introduction
    3.1.1. Morphodynamic equilibrium
    3.1.2. Criteria for equilibrium
    3.1.3. Aim of the study
    3.2. Model description
    3.2.1. Morphological factor
    3.2.2. Dry cell erosion and bank erosion
    3.2.3. Geometry
    3.3. Results
    3.3.1. Fixed banks
    3.3.2. Eroding banks
    3.3.3. Energy dissipation
    3.3.4. Validation
    3.4. Discussion
    3.4.1. Grid resolution
    3.4.2. Sea level rise
    3.4.3. Initial conditions
    3.4.4. Energy dissipation
    3.4.5. Energy flux
    3.5. Conclusions
    4. Morphodynamic modeling of tidal channel evolution in comparison to empirical PA relationship
    4.1. Introduction
    4.1.1. PA relationship
    4.1.2. Aim and approach
    4.2. Model set-up
    4.3. Results
    4.3.1. Evolution of basin mouth connected to a deep and short basin
    4.3.2. Impact of basin geometry on basin mouth evolution
    4.3.3. Time scales and sea level rise
    4.3.4. Interaction between tidal channels and inlets
    4.4. Conclusions
    4.5. Acknowledgements
    5. Reproduction of the Western Scheldt bathymetry by means of a process-based, morphodynamic model
    5.1. Introduction
    5.1.1. Scope
    5.1.2. Aim of the study
    5.1.3. Approach
    5.1.4. Case study
    5.2. Model set up
    5.3. Model results
    5.3.1. General observations
    5.3.2. Visual comparison of pattern development
    5.3.3. Comparison of hypsometries
    5.3.4. Brier Skill Score (BSS)
    5.4. Discussion
    5.5. Conclusions
    6. Process-based, morphodynamic hindcast of decadal deposition patterns in San Pablo Bay 1856-1887
    6.1. Introduction
    6.1.1. Scope
    6.1.2. Aim of the study
    6.1.3. Approach
    6.2. Description of San Francisco Estuary
    6.2.1. Geometry

    Biography

    Mick van der Wegen studied Civil Engineering at Delft University of Technology. He then joined the International Institute for Infrastructural, Hydraulic and Environmental Engineering (IHE) in Delft and has worked on Coastal Engineering and Port Development. His main subjects of expertise are salt intrusion and density currents, integrated coastal zone management and morphodynamic modeling of coastal systems.