Predicting Morphodynamics for Beach Intertidal Systems in the North Sea: A Space-Time Stochastic Approach

Round 1

Reviewer 1 Report

This manuscript use modelling approach to examine the long term morphodynamic change of intertidal beach profile and provide some degree of predictions. The direction of MS is clear and the analysis is acceptable. I recommend some minor revision as below:

 

• I would suggest the title be modified as “Predicting morphodynamics beach intertidal systems: a space-time stochastic approach based on beach in the North Sea”. Volume change is difficult to be understand by general audiences. Also, beach morphodynamics is very different among climate zones and marine system. So, indicating this is a study on North Sea system is important.

 

• Introduction, line 29-31, the authors states “Understanding and predicting coastal morphodynamics are critical for the safety of the existing ecosystems, infrastructures and for mitigating expected damages from future changes.” This is true. However, morphodynamics of beach can also affect biodiversity and biological component. For example, morphodynamics of beaches can affect the nesting ecology of sea turtles, burrowing of bivalves and the presences of sand crabs (Cheng et al. 2009; Sonmez, 2019; Boyco, 2020). This should be have a new sentence to mention these after these sentences. The following references can be cited to add such biological component in the introduction.

 

Serrano, R.H., Lastra, M., Lopez J (2002). he influence of sediment grain size on burrowing, growth and metabolism of Donax trunculus L. (Bivalvia: Donacidae). Journal of Sea Research 47: 85-95

 

Sönmez B. 2019. Morphological variations in the green turtle (Chelonia mydas): A field study on an eastern Mediterranean nesting population. Zool Stud 58:16. doi:10.6620/ZS.2019.58-16.

 

Cheng, I.J., Huang, C.T., Hung, P.Y., Ke, B.Z. Kuo, C.W., Fong, C.L. 2009. Ten years of monitoring the nesting ecology of the green turtle Chelonia mydas, on Lanyu, Taiwan. Zoological Studies 48: 83-94

 

Boyko CB. 2020. New records of sand crabs (Crustacea: Decapoda: Albuneidae and Blepharipodidae) from the western Pacific with

description of two new species of Paralbunea Serène, 1977. Zool Stud 59:15. doi:10.6620/ZS.2020.59-15.

 

Lines 38-39 – “Why the morphology of sand beaches will change with time?– The author stated wave storms. Sea level changes, sediment fluxes. Can you state there are regular seasonal events – mosoons, seasonal current patterns and stochastic events: storms or other factors?

 

Introduction should give some baseline characteristics of the North Sea system? Winter – general great wind and waves. Past century, any big physical events and variations happens that can affect beach morphodynamics?

 

Morphology and slope change – also affect grain size, this should be mentioned. This can imply the effect on the biota of burrowing organisms including bivalves and decapods (examples as in Donax and Sand crabs).

 

Introduction, can you emphasize the novelty of your study? Is this the first one to conduct in the N. Sea? Please elaborate.

 

Methods: Line 131 – “Light Detection And Ranging (LiDAR)” – How, please provide details. Conducting the survey in-situ during low spring tides?

 

Discussion: Can this approach to be used in other marine system with different tidal range? For example, in Mediternean, the tidal range is very small. In UK, tidal range can be bigger than 10 m, in West Pacific, it is about 2.5 metres. Does this approach can be used for analysis in these specific cases?

 

Fig. 1 – should provide photos of the beaches. Also, provide photo of beaches with different profiles and changes will be very useful. Fig 1C What is mean by “typical”? Typical in North Sea system? Note everyone’s feeling on typical is different. Better to plot a profile with 10 replicates and show the general mean profiles.

 

Fig. 5, legends, need to explain what is X in the figure legend, so readers will no need to refer to text again.  

 

 

Author Response

See attached document

Author Response File: Author Response.pdf

Reviewer 2 Report

Beyond the statistical methods used, the manuscript presents a new way of seeing the dynamics to which a ridge and runnel system is subject. This method can be appropriately implemented with the addition of other parameters besides the morphological ones (e.g. grain size, here supposed uniform all over the profile) and external forcing (wave climate) can lead to a better knowledge of this complex system.

In some points, the variations indicated only with the absolute value (which is indispensable for the application of this statistic) make impossible the perception of the processes.

Studying the behavior of a beach (morphology and sedimentology) I found that it was Markovian (early 1980’s); this aspect could be taken into consideration. For ethical reasons I never ask to read or quote my works when I do a review.

The main question that arose in reading this ms. is what is the value of a volume change analysis that does not extend to the depth of closure. The authors should write something about this. Most of the observations reported in the publications cited (e.g. line 35) refer to the entire profile, both in the emerged, intertidal and submerged part.

I like the distinction between behavior and evolution (line 42)

Line 93: Can a beach be classified as dissipative without giving its surf scaling parameter?

Line 95 To know which is the annual net longshore transport could help in understanding the ineffectiveness of the measured volume changes.

Line 227: if so, mean slope decreases. Which is the morphodynamic implication?

Line 253 The value of 3 years, which comes out of the statistics, has some relationship with physical processes (e.g. storm return period). The reader is left with curiosity!

Fig. 6 Check ordinates label

Fig. 10 and related text. I understand the need to use absolute values, but then you can't know if you are losing or gaining. A brief observation on this could be made.

Fig. 11 and related text. How does the accretionary status of this beach influence this result?

 

Could it be better explained if the elevation variations are greater offshore than onshore?

The different use of the symbol ’m': normal, italic, attached or detached from the numerical value, are they distractions or do they have a meaning?

Author Response

See attached document

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I think the comments were addressed and the MS can be accepted for publication.