Wave Overtopping Discharge for Very Gently Sloping Foreshores

Round 1

Reviewer 1 Report

The paper analyzes the relevance of the Tm-1,0 to study the wave overtopping on dikes when there is a gente foreshore. In those cases, the Tm-1,0 is not constant from deepwater conditions, since there is a migration of energy to the lower frequencies due to wave breaking. The paper is novel, it is well written in English and well structured. My main concern is related to the reliability of SWASH. The authors compare empirical tools based on experimental data with numerical simulations given by SWASH without any calibration assuming that those are the correct precitions; how can the authors demonstrate that SWASH results are reliable?

The analysis is focused on thes results of the numerical models SWASH and SWAN. From the analysis it seems that SWAN is not able to properly perform the migration of energy in very gente slopes; does it mean that the method of Battjes and Groenendijk (2000) implemented in SWAN is not useful in very gentle slopes?

The manuscript is difficult at some times because there are many distances used as boundary conditions (I think) for the different models. Please, specify on a figure (such as Figure 1), the points where you obtain the wave characteristics. In Figure 1, identify in higher letters the countries or singular areas. Identify where the dike is.

It is not clear how you use SWAN and SWASH, do you nest them? Are both used in the same area but, as you state that results from SWAN are not reliable with wave breaking you used SWASH in the surf zone? Please include a Figure with an example of the grids used in SWAN and SWASH. How are the boundary conditions implemented, only on one side of the grid or in all of them?

Regarding the results of wind influence, it seems you can do the simulations without wind (since all the results are almost coincident at the toe of the dike). Why did you chose 12m/s?

Please provide the formula of Hofland to estimate the Tm-1,0.

It is better to use m to identify the bottom slope; cotθ is usually used to identify the dike slope (In fact in line 311 you use tan(alfa)=1:4 for the dike slope).

In table 1, to be consistent with the prepositions, Hs must read “spectral significant wave height at…”

In Figure 6, specify that HF and LF are estimated by SWASH.

In Figure 7, It does not make sense to obtain a wave spectra at depth equal to 0 m.

I miss a recommendation for practitioners on how to use existing wave overtopping formulas when there is a very gentle slopes without using SWASH. From Figure 8, probably you can try to provide a rule of thumb for designers to evaluate the correct Tm-1,0 to be used in Van Gent or Altomare formulas.

Specific issues

In line 356 “…the overtopping discharge only decreased by less…”

In line 374 “… Iribarren…”

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Very interesting study focusing on gentle slopes. I like it because it is well beyond the capabilities of any laboratory experiments just due to impossible geometric constrains, yet the study is relevant to many coastlines. The authors are clearly experts in this type of investigation, have used the model well and documented their approach, parameters and results clearly in this manuscript. Should be useful for the interested community.

Author Response

Thank you very much for your extremely kindness in your judgement

Round 2

Reviewer 1 Report

The authors answered all my queries. I suggest to modify figure 1 to make bigger numbers on bathymetry and to better identify the boundary conditions of SWAN and SWASH models.

Author Response

Please see the attachment

Author Response File: Author Response.pdf