Modeling of
611
Part C | 28.1
28. Modeling of Coastal Morphological Processes
J.A. Dano Roelvink, Dirk-Jan R. Walstra, Mick van der Wegen, Roshanka Ranasinghe
Morphology is the study of forms, whether of animals, plants or words; coastal morphology is the
study of coastal forms. Some of these forms are
hard (like rock) and do not move much. Others, such as beaches, dunes, channels, sandbars,
shoals, are made of mud, sand, or even gravel and
move all the time. Understanding and predicting
these motions are what coastal morphologists try
to do.
The approach we take depends on the scale
of the problem or process we are interested in.
This scale ranges from small-scale ripples to entire
tidal inlets or coast lines. The larger the length
scale, the larger the timescale; the upper beach
profile can adapt to a storm in hours; the coastline
around a port can take decades to adapt, and the
effects of closing a tidal inlet can be felt for many
centuries.
In coastal engineering, morphology is a core
discipline. It is needed to assess damage to
beaches, dunes, and barrier islands during extreme events; it is needed to understand and
mitigate coastal erosion; it is important in the
design of ports, to assess impact on the coast and
estimate dredging requirements for the navigation
channel and basins; it is needed in the design
and impact studies of land reclamations and finally, it provides scenarios to use in coastal zone
management.
In this chapter, we will first discuss different
types of coastal morphology models. We will then
zoom in and focus on process-based modeling in
more detail. First, the fundamentals of processbased modeling are described, which is followed
by short descriptions of the commonly used types
of process-based models. Subsequently, a number
28.1 Types of Coastal Models........................ 611
28.1.1 Physical Scale Models ................ 611
28.1.2 Analytical Models ...................... 612
28.1.3 (Semi-)Empirical Models ............ 612
28.1.4 Process-Based Models ............... 612
28.2 Principles of Process-Based
Morphodynamic Modeling.................... 613
28.2.1 What Is a Process-Based
Morphodynamic Model?............. 613
28.2.2 Mass Balance Equation .............. 613
28.2.3 Bed Celerity .............................. 613
28.2.4 Development
Toward Equilibrium ................... 614
28.2.5 Types of Process-Based Models ... 614
28.2.6 Upscaling Techniques ................ 617
28.3 Modeling Approaches .......................... 619
28.3.1 Storm Event Modeling................ 619
28.3.2 Modeling Cross-Shore Breaker
Bar Cycles ................................. 623
28.3.3 Long-Term Modeling
of Estuaries............................... 626
28.4 Future Directions ................................. 629
28.4.1 Ensemble Modeling ................... 629
28.4.2 Biogeomorphology .................... 629
28.4.3 Dune Modeling ......................... 630
28.4.4 Coral Reefs ................................ 630
28.4.5 Modeling Stratigraphy................ 630
28.4.6 Morphological Modeling
of Tsunami Deposits .................. 630
28.5 Nomenclature...................................... 631
References................................................... 631
of modeling approaches considering different
scales, from storm-event modeling to long-term
modeling of estuaries are presented. We conclude
by discussing some future directions.
28.1 Types of Coastal Models
28.1.1 Physical Scale Models
We generally approach these problems with models,
of which we have a variety at our disposal or under development. To start with, there are the physical
scale models, which appear to be starting a new life,
after a period in which all the focus was on numerical models. The Dutch design rules for dune erosion
611
Part C | 28.1
28. Modeling of Coastal Morphological Processes
J.A. Dano Roelvink, Dirk-Jan R. Walstra, Mick van der Wegen, Roshanka Ranasinghe
Morphology is the study of forms, whether of animals, plants or words; coastal morphology is the
study of coastal forms. Some of these forms are
hard (like rock) and do not move much. Others, such as beaches, dunes, channels, sandbars,
shoals, are made of mud, sand, or even gravel and
move all the time. Understanding and predicting
these motions are what coastal morphologists try
to do.
The approach we take depends on the scale
of the problem or process we are interested in.
This scale ranges from small-scale ripples to entire
tidal inlets or coast lines. The larger the length
scale, the larger the timescale; the upper beach
profile can adapt to a storm in hours; the coastline
around a port can take decades to adapt, and the
effects of closing a tidal inlet can be felt for many
centuries.
In coastal engineering, morphology is a core
discipline. It is needed to assess damage to
beaches, dunes, and barrier islands during extreme events; it is needed to understand and
mitigate coastal erosion; it is important in the
design of ports, to assess impact on the coast and
estimate dredging requirements for the navigation
channel and basins; it is needed in the design
and impact studies of land reclamations and finally, it provides scenarios to use in coastal zone
management.
In this chapter, we will first discuss different
types of coastal morphology models. We will then
zoom in and focus on process-based modeling in
more detail. First, the fundamentals of processbased modeling are described, which is followed
by short descriptions of the commonly used types
of process-based models. Subsequently, a number
28.1 Types of Coastal Models........................ 611
28.1.1 Physical Scale Models ................ 611
28.1.2 Analytical Models ...................... 612
28.1.3 (Semi-)Empirical Models ............ 612
28.1.4 Process-Based Models ............... 612
28.2 Principles of Process-Based
Morphodynamic Modeling.................... 613
28.2.1 What Is a Process-Based
Morphodynamic Model?............. 613
28.2.2 Mass Balance Equation .............. 613
28.2.3 Bed Celerity .............................. 613
28.2.4 Development
Toward Equilibrium ................... 614
28.2.5 Types of Process-Based Models ... 614
28.2.6 Upscaling Techniques ................ 617
28.3 Modeling Approaches .......................... 619
28.3.1 Storm Event Modeling................ 619
28.3.2 Modeling Cross-Shore Breaker
Bar Cycles ................................. 623
28.3.3 Long-Term Modeling
of Estuaries............................... 626
28.4 Future Directions ................................. 629
28.4.1 Ensemble Modeling ................... 629
28.4.2 Biogeomorphology .................... 629
28.4.3 Dune Modeling ......................... 630
28.4.4 Coral Reefs ................................ 630
28.4.5 Modeling Stratigraphy................ 630
28.4.6 Morphological Modeling
of Tsunami Deposits .................. 630
28.5 Nomenclature...................................... 631
References................................................... 631
of modeling approaches considering different
scales, from storm-event modeling to long-term
modeling of estuaries are presented. We conclude
by discussing some future directions.
28.1 Types of Coastal Models
28.1.1 Physical Scale Models
We generally approach these problems with models,
of which we have a variety at our disposal or under development. To start with, there are the physical
scale models, which appear to be starting a new life,
after a period in which all the focus was on numerical models. The Dutch design rules for dune erosion