1) The document presents a pheno-metric approach for assessing coastal dynamics using key parameters like dominant wave period, waterlevel variation, onshore topography, and sediment characteristics. 2) These four parameters are argued to capture the variation in coastal shapes around the world, and allow for forecasting future changes. 3) The approach models coastal behavior within boundaries of the seabed, water levels, relevant topography, and defines characteristics like shoreface slope and presence of sandbanks based on the key parameters.

1. © Marco Pluijm, 30/09/2018
Pheno-Metric Coastal Behaviour Assessment
The Power of assessing coastal dynamics in their true dimensions
Published on September 28, 2018
Marco Pluijm
Innovator and Seasoned Professional
Referring to enhanced understanding and quantitative assessment of the behaviour and interaction
between natural morphological phenomena on the basis of an holistic, phenomenologic approach.
Accumulating into a few key parameters on the basis of which the behaviour and anticipated impact
response of sandy coasts can be assessed in numbers.
This approach kicks off with the statement that basically there are no principle differences in
coastline behaviour around the world. The variation in shape and performance is the result of the
relative interaction between just a few parameters. Matter of subject now is which these are and
how that works out in terms of adequate description of the system and forecasting towards changes
and future developments.
Which in this case are brought down to four key parameters, as there are 1) dominant wave period,
2) waterlevel variation, 3) onshore topography and 4) sediment characteristics. No more, the other
parameters are somehow derivatives from these four. Such as shore face sloping, set up and surge,
presence and number of sandbanks, etc
The model is thought to be confined in between boundaries as shown in the picture above.
As there are :
A. Lower boundary, the area covering the seabed outside closure depth, raising with the foreshore
up to the still water line. Closure depth defined as the depth below which no relevant seabed
changes are observed

2. © Marco Pluijm, 30/09/2018
B. Upper boundary, covering both still water level and the relevant part of the onshore
topography
C. Land side boundary, backside of relevant topography, which can be both dry or wet
D. Seaward boundary, covering the relevant part of the area seaward of the closure depth
In which graph we can distinguish
Wave period, subdivided into 1) bound long waves (ranging up to 250 seconds plus), 2) swell waves
(ranging from 10 to 25 seconds) and short waves (under 10 seconds)
Shoreface, in relation to sediment characteristics, either 1) steep (long wave/swell dominated), 2)
intermediate (long/short wave affected) and 3) shallow (short wave dominated)
Waterlevel variation, set up and surge, following wave period and shoreface variation in
combination with the onshore topography (intertidal, wet or dry).
Onshore topography in interaction with wave period and sediment characteristics.
Presence of sand banks and other near shore phenomena, varying from 1 to 3 banks (max)
depending on the wave period variation (long, swell and short waves) and sediment chraracteristics
Potential presence of submerged bars, natural or intervened (nears shore nourishment), relating to
the same key parameters wave period, shoreface and sediment characteristics. Which, once
assessed can be used as planning and design graph for near shore nourishments.
Forming the relevant cross section. Any longshore activity is seen as input without a gradient per
section and so with limited effect, if any
Example of thus assessed pheno-metric graph for crest width, relative waterdepth and sediment
characteristics related to a near shore submerged is shown above
By following this approach additional benefit is not only that the behaviour is better and thoroughly
understood but can also be made non-site specific
In order to encourage discussion and more wide spread use, it is stated that none of this approach is
actually new. Ample applications are known for stability of estuaries and tidal inlets. The novelty sits
in the coastal application.