Flood Susceptibility and Sediment Transport Analysis of Stromboli Island after the 3 July 2019 Paroxysmal Explosion

Round 1

Reviewer 1 Report

The manuscript entitled “Flood susceptibility and sediment transport analysis at the Stromboli island after the 3^rd July 2019 paroxysmal explosion” written by Areu-Rangel and co-authors presents an analysis of volcano eruption impact on hydrological regime in the catchment of the island mention in the paper title. The main research tool is the application of the Iber model for simulation of 2D flow and sediment transport on the hills of the Stromboli volcano. The simulations are preceded by deep analysis of meteorological, hydrological and geological conditions on the island. The research is well prepared and the numerical experiments are properly designed. The paper is clearly written and almost all elements are properly described. Some small corrections could be made. These are listed below:

1. The purpose may be reformulated. The Authors write

“In this study the effect of the change in land use determined by the wildfire on the possible increase in runoff as well as on sediment transport, is analysed.”

in the last passage of the Introduction. I suggest to formulate the research hypothesis and clearly write what is expected as the result of the presented analyses.

2. In the sub-chapter “2. Hydrological study for the estimation of flood discharges” we can read that

“In accordance with what is indicated in the report, the hydrogeological study and flood risk assessment were carried out, in this work, for the return periods corresponding to 50, 100 and 300 years.”

I wonder how these return periods and flow values correspond to EU Flood Directive. In my opinion, this information could be important, because the Stromboli island belongs to Italy, which is a member of EU. Hence the regulations of Flood Directive should be also obligatory in this region.

3. The modeling methodology should be better explained. I understand that it was described and discussed in another paper, but the basic information is necessary. I expect to read
   • what is the type of the model (hydrological/hydrodynamic, etc.),
   • what are the balance equations (mass/momentum/some empirical formula, etc.),
   • what are the boundary conditions specific for the modeled case

3. In the description of the Iber model, the Authors write (lines 135-136)

“The study area was discretized with an unstructured triangular mesh of 243139 elements with size of 8 m.”

How is the size of the triangle cell determined? It’s not obvious, so it should be written explicitly.

5. The Conclusions are written as a summary of the presented research. I think that this section should include other information. Such elements should be described there:
   • the importance of the presented methodology,
   • the meaning of the findings for the research area,
   • the meaning of the finding for the local community,
   • the limitations of the applied methodology,
   • the estimated uncertainty of results and
   • the possible further developments.

In my opinion, it could increase the value of the paper.

The mentioned drawbacks are really small. Hence, I think the additional review is not necessary.

Author Response

We have carefully reviewed the reviewer’s comments and have revised the manuscript accordingly. Our responses are given in a point-by-point manner below. Changes in the text are tracked in Bold.

We hope the revised version is now suitable for publication and look forward to hearing from you in due course.

Sincerely,

 

Rosanna Bonasia

 

Response to Reviewer 1 Comment:

 

The manuscript entitled “Flood susceptibility and sediment transport analysis at the Stromboli island after the 3rd July 2019 paroxysmal explosion” written by Areu-Rangel and co-authors presents an analysis of volcano eruption impact on hydrological regime in the catchment of the island mention in the paper title. The main research tool is the application of the Iber model for simulation of 2D flow and sediment transport on the hills of the Stromboli volcano. The simulations are preceded by deep analysis of meteorological, hydrological and geological conditions on the island. The research is well prepared and the numerical experiments are properly designed. The paper is clearly written and almost all elements are properly described. Some small corrections could be made. These are listed below:

 

1. The purpose may be reformulated. The Authors write

“In this study the effect of the change in land use determined by the wildfire on the possible increase in runoff as well as on sediment transport, is analysed.”

in the last passage of the Introduction. I suggest to formulate the research hypothesis and clearly write what is expected as the result of the presented analyses.

The last part of the Introduction section was modified with the re-formulation of the study hypothesis as follows:

“This work is aimed to carry out the first study of the effect of an eruption-induced wildfire on the hydraulic structure of a volcanic area. The study hypothesis is that the change in land use caused by the fire can increase the surface runoff due to rainfall and generate erosion and re-mobilization of the eroded material.”

2. In the sub-chapter “2. Hydrological study for the estimation of flood discharges” we can read that

“In accordance with what is indicated in the report, the hydrogeological study and flood risk assessment were carried out, in this work, for the return periods corresponding to 50, 100 and 300 years.”

I wonder how these return periods and flow values correspond to EU Flood Directive. In my opinion, this information could be important, because the Stromboli island belongs to Italy, which is a member of EU. Hence the regulations of Flood Directive should be also obligatory in this region.

Our hazard estimates have been carried out according to the Sicily Region directives. The EU Flood Directive 2007/60/CE in Italy it was implemented by Legislative Decree D.Lg. 49/2010 and for the Sicily Region by the Flood Risk Management Plan (Piano di Gestione del Rischio di Alluvioni (for the document see the following link: http://pti.regione.sicilia.it/portal/page/portal/PIR_PORTALE/PIR_LaStrutturaRegionale/PIR_PresidenzadellaRegione/PIR_AutoritaBacino/PIR_Areetematiche/PIR_Pianificazione/PIR_PianoGestioneDirettiva200760CE/PIR_PianoGestioneRischioAlluvioni2015/PIR_ValutazioneAmbientaleStrategica/PIR_Documentazione/RA_VAS_PGRA_rev_2018_11_luglio_2018_compressed.pdf ; in Italian).

 

According to the Flood Risk Management Plan, that we have followed in our work, flood hazard maps must contain the perimeter of the geographic areas that could be affected by floods according to different scenarios, highlighting the areas where debris flows and flood phenomena with a high volume of sediment transported can occur. The scenarios are:

- rare floods of extreme intensity: return time up to 500 years from the event (low probability);

- infrequent floods: return time between 100 and 200 years (medium probability);

- frequent floods: return time between 20 and 50 years (high probability).

For each scenario indicated above, at least the following elements must be indicated:

- extension of the flood;

- water height or level;

• flow characteristics (speed and flow rate).

The reference to the EU Flood Directive has been added in the corresponding section.

 

3. The modeling methodology should be better explained. I understand that it was described and discussed in another paper, but the basic information is necessary. I expect to read

what is the type of the model (hydrological/hydrodynamic, etc.),

what are the balance equations (mass/momentum/some empirical formula, etc.),

what are the boundary conditions specific for the modeled case.

In accordance with the reviewer’s suggestion, Sub-Section 2.3 Flood model with the software IBER has been modified by adding the following information:

“This module solves the depth-averaged Shallow Water Equations, also known as two-dimensional Saint Venant Equations. This equations assume a hydrostatic pressure distribution and a relative uniform in depth velocity distribution. The hypothesis of hydrostatic pressure and uniform distribution of velocity in depth are reasonably fulfilled in the flow in rivers and estuaries. The hydrodynamic module solves the conservation of mass and momentum equations in the two horizontal directions, where the bottom friction has a double effect on the flow equations: it produces a friction force that is opposed to the average speed, and, on the other hand, it produces turbulence. In the hydrodynamic calculations, the software allows the use of two types of boundary conditions: open or closed, where closed boundaries are waterproof, while for open boundaries different conditions can be imposed depending on the flow regime (subcritical or supercritical).”

4. In the description of the Iber model, the Authors write (lines 135-136)

“The study area was discretized with an unstructured triangular mesh of 243139 elements with size of 8 m.”

How is the size of the triangle cell determined? It’s not obvious, so it should be written explicitly.

The procedure adopted for choosing the size of the triangular cells was specified by adding the following text:

“The optimal size of the triangular elements was chosen following the implementation of various iterative tests with different triangles sizes. The tests were aimed at meeting the dimension that produced the best results with the shortest calculations time. The 8 $m$ size allowed a calculation time of 2.3 hours for each simulation.”

5. The Conclusions are written as a summary of the presented research. I think that this section should include other information. Such elements should be described there:

the importance of the presented methodology,

the meaning of the findings for the research area,

the meaning of the finding for the local community,

the limitations of the applied methodology,

the estimated uncertainty of results and

the possible further developments.

In my opinion, it could increase the value of the paper.

We agree with the reviewer that the elements mentioned can improve the section of conclusions. For this reason, the following paragraph has been added to the end of the section:

“Although there are many published studies on the effects of volcanic eruptions on the watersheds, the effect that eruptions-induced wildfires generates on surface re-emergence had never been addressed. This work shows that even in volcanic areas with little predisposition to trigger floods and debris flows, eruptions-induced wildfires can alter hydrological conditions and increase the hazard related with these phenomena. The results obtained have a further important impact on communities and local authorities, since they allow to define floods hazard scenarios. In fact, the methodology presented here is useful to obtain high spatial and temporal resolution for flooding hazard assessment, since it is based on the use of a solid model that solves the 2D Saint Venant hydrodynamic equations for high precision water depth, velocity and flow rate calculations. A possible further development could be the estimation of the probability of inundation, vulnerability and the exposed value in order to produce flood risk maps, which could be a valuable tool for urban and regional planning on the island of Stromboli.”

I recommend to accept the manuscript after minor revisions. The mentioned drawbacks are really small. Hence, I think the additional review is not necessary.

Reviewer 2 Report

Numerical modelling without any verified input data has very limited predicative value

Author Response

We have carefully reviewed the reviewer’s comments and have revised the manuscript accordingly. Our responses are given in a point-by-point manner below.

We hope the revised version is now suitable for publication and look forward to hearing from you in due course.

Sincerely,

 

Rosanna Bonasia

 

Response to Reviewer 2 Comment:

 

Numerical modelling without any verified input data has very limited predicative value.

 

The Iber software has been extensively validated in many previous works, especially with regard to river floods, currents in estuaries, and modeling of rainfall-runoff processes. As far as surface hydrodynamics simulations are concerned, the Saint Venant equations in 2D, solved by the software, are considered the best representation of the flood process. For the solution of these equations, the only parameter that must be calibrated is the Manning coefficient for the different soils considered, which is established on the basis of river engineering manuals. The rainfall input values refer to the weather station on the island.

For what concerns the sediment transport simulations, Iber calculates the sediment transport using the equations of the non-cohesive sediment transport, with uniform grain size, in a non-stationary regime. The shear stress of the bottom depends on the roughness of the granule and the morphology of the bottom. However, the shear stress of the granule is the factor that most influences the transport of sediment in contact with the bottom. Hence, the main input required in this module is the characteristic of the granule, which, for the context of the study area, was taken from the work of Verrucci et al. 2019 abundantly mentioned in the text.

Reviewer 3 Report

sustainability-757178-peer-review-v1

No	Lines	Comments
1		Title: The Title reflects the paper’s content accurately.
2	1-16	Abstract: The Abstract determines the paper’s content and objectives in a very manifest and complete fashion.
3	17-58     22   30-31   31           33	1.       Introduction   The following sources should be mentioned: Increasing erosion rate and drainage mass flux (water and sediment) in the affected basin is found in [1] While vegetation has positive effects on the water interception suction, evapotranspiration and infiltration strongly affect runoff processes [2]. HCL content of volcanic ash [3]   Phosphorus sediment content in [4]   Sediment is in [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]   Debris flow in [15], [16]   Wildfire severity and  analysis of land cover (LC) and land use (LU) changes in Stromboli using  PLÉIADES-1 and Sentinel-2 satellite imagery is addressed in [17].   Scientific uncertainty in wildfire and flood risk mitigation is in [18]
4	59-178   107     158	2.       Materials and Methods   Chen’s 1983 process was employed. Justify the use of this process versus some other modern processes.   Justify why suspended sediment transport is not considered. Otherwise very well composed.
	179-215	3.       Results   Good analysis
	216-272	4.       Discussion   The discussion is in depth and exhaustive
	273-295	5.       Conclusions   A good summation of the work in this paper presenting important facts.

 

Concluding Remarks: Minor write-up

 

Suggested References

 

[1]      D. Panagoulia, D. Zarris, and K. Maggina, “An Assessment of the Interaction Between Storm Events and Sediment Transport, Proceedings of the 5th International Synposium on Ecohydraulics, Aguatic Habitats: Analysis & Restoration,” in Proceedings of the 5th International Synposium on Ecohydraulics, Aguatic Habitats: Analysis & Restoration, 2004, pp. 281–286.

[2]      D. Panagoulia, “Hydrological modeling of a medium-size mountainous catchment from incomplete meteorological data,” J. Hydrol., no. 137(1–4), pp. 279–310, 1992.

[3]      X. Gutierrez, F. Schiavi, and H. Keppler, “The adsorption of HCl on volcanic ash,” Earth Planet. Sci. Lett., no. 438, pp. 66–74, 2016.

[4]      J. H. Son, S. Kim, and K. H. Carlson, “Effects of wildfire on river water quality and riverbed sediment phosphorus,” Water. Air. Soil Pollut., vol. 226, no. 3, 2015.

[5]      D. V. Malmon, S. L. Reneau, D. Katzman, A. Lavine, and J. Lyman, “Suspended sediment transport in an ephemeral stream following wildfire,” J. Geophys. Res. Earth Surf., vol. 112, no. 2, pp. 1–16, 2007.

[6]      C. C. Rhoades, D. Entwistle, and D. Butler, “The influence of wildfire extent and severity on streamwater chemistry, sediment and temperature following the Hayman Fire, Colorado,” Int. J. Wildl. Fire, vol. 20, no. 3, pp. 430–442, 2011.

[7]      K. M. Cawley et al., “Characterization and spatial distribution of particulate and soluble carbon and nitrogen from wildfire-impacted sediments,” J Soils Sediments, no. 18, pp. 1314–1326, 2018.

[8]      J. A. Warrick, J. A. Hatten, G. B. Pasternack, A. B. Gray, M. A. Goni, and R. A. Wheatcroft, “The effects of wildfire on the sediment yield of a coastal California watershed,” Bull. Geol. Soc. Am., vol. 124, no. 7–8, pp. 1130–1146, 2012.

[9]      P. N. Owens, W. H. Blake, T. R. Giles, and N. D. Williams, “Determining the effects of wildfire on sediment sources using 137Cs and unsupported 210Pb: The role of landscape disturbances and driving forces,” J. Soils Sediments, vol. 12, no. 6, pp. 982–994, 2012.

[10]    P. N. J. Lane, G. J. Sheridan, and P. J. Noske, “Changes in sediment loads and discharge from small mountain catchments following wildfire in south eastern Australia,” J. Hydrol., vol. 331, no. 3–4, pp. 495–510, 2006.

[11]    M. Parise and S. H. Cannon, “Wildfire impacts on the processes that generate debris flows in burned watersheds,” Nat. Hazards, vol. 61, no. 1, pp. 217–227, 2012.

[12]    S. E. Ryan, K. A. Dwire, and M. K. Dixon, “Impacts of wildfire on runoff and sediment loads at Little Granite Creek, western Wyoming,” Geomorphology, vol. 129, no. 1–2, pp. 113–130, 2011.

[13]    P. N. Owens, E. L. Petticrew, and M. van der Perk, “Sediment response to catchment disturbances,” J. Soils Sediments, vol. 10, no. 4, pp. 591–596, 2010.

[14]    J. J. Major, “POST-ERUPTION HYDROLOGY AND SEDIMENT TRANSPORT IN VOLCANIC RIVER SYSTEMS,” Water Resour. Impact, no. March, pp. 10–15, 2003.

[15]    J. B. Loverich, A. M. Youberg, M. J. Kellogg, and J. E. Fuller, “Post-Wildfire Debris-Flow & Flooding Assessment: Coconino County, Arizona,” 2017.

[16]    J. D. Pelletier and C. A. Orem, “How do sediment yields from post-wildfire debris-laden flows depend on terrain slope, soil burn severity class, and drainage basin area? Insights from airborne-LiDAR change detection,” Earth Surf. Process. Landforms, vol. 39, no. 13, pp. 1822–1832, 2014.

[17]    A. Turchi, F. Di Traglia, T. Luti, D. Olori, I. Zetti, and R. Fanti, “Environmental Aftermath of the 2019 Stromboli Eruption,” Remote Sens., no. 12, pp. 1–23, 2020.

[18]    T. Neale and J. K. Weir, “Navigating scientific uncertainty in wildfire and flood risk mitigation: A qualitative review,” Int. J. Disaster Risk Reduct., vol. 13, pp. 255–265, 2015.

Comments for author File: Comments.pdf

Author Response

We have carefully reviewed the reviewer’s comments and have revised the manuscript accordingly. Our responses are given in a point-by-point manner below. Changes in the text are tracked in Italic.

We hope the revised version is now suitable for publication and look forward to hearing from you in due course. Sincerely,

Rosanna Bonasia

Response to Reviewer 3 Comments:

1.

Title: The Title reflects the paper’s content accurately.

2.

Abstract:

The Abstract determines the paper’s content and objectives in a very manifest and complete fashion.

We thank the reviewer for the positive feedback on the title and abstract.

3.

Introduction:

The following sources should be mentioned:

Increasing erosion rate and drainage mass flux (water and sediment) in the affected basin is found in [1]

While vegetation has positive effects on the water interception suction, evapotranspiration and infiltration strongly affect runoff processes [2].

HCL content of volcanic ash [3]

Phosphorus sediment content in [4]

Sediment is in [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]

Debris flow in [15], [16]

Wildfire severity and  analysis of land cover (LC) and land use (LU) changes in Stromboli using  PLÉIADES-1 and Sentinel-2 satellite imagery is addressed in [17].

Scientific uncertainty in wildfire and flood risk mitigation is in [18]

We carefully revised the suggested bibliography, and, based on the main aspects covered in the introduction, we added the following sources:

[1]      D. Panagoulia, D. Zarris, and K. Maggina, “An Assessment of the Interaction Between Storm Events and Sediment Transport, Proceedings of the 5th International Synposium on Ecohydraulics, Aguatic Habitats: Analysis & Restoration,” in Proceedings of the 5th International Synposium on Ecohydraulics, Aguatic Habitats: Analysis & Restoration, 2004, pp. 281–286.

[2]      D. Panagoulia, “Hydrological modeling of a medium-size mountainous catchment from incomplete meteorological data,” J. Hydrol., no. 137(1–4), pp. 279–310, 1992.

[4]      J. H. Son, S. Kim, and K. H. Carlson, “Effects of wildfire on river water quality and riverbed sediment phosphorus,” Water. Air. Soil Pollut., vol. 226, no. 3, 2015.

[5]      D. V. Malmon, S. L. Reneau, D. Katzman, A. Lavine, and J. Lyman, “Suspended sediment transport in an ephemeral stream following wildfire,” J. Geophys. Res. Earth Surf., vol. 112, no. 2, pp. 1–16, 2007.

[6]      C. C. Rhoades, D. Entwistle, and D. Butler, “The influence of wildfire extent and severity on streamwater chemistry, sediment and temperature following the Hayman Fire, Colorado,” Int. J. Wildl. Fire, vol. 20, no. 3, pp. 430–442, 2011.

[8]      J. A. Warrick, J. A. Hatten, G. B. Pasternack, A. B. Gray, M. A. Goni, and R. A. Wheatcroft, “The effects of wildfire on the sediment yield of a coastal California watershed,” Bull. Geol. Soc. Am., vol. 124, no. 7–8, pp. 1130–1146, 2012.

[10]    P. N. J. Lane, G. J. Sheridan, and P. J. Noske, “Changes in sediment loads and discharge from small mountain catchments following wildfire in south eastern Australia,” J. Hydrol., vol. 331, no. 3–4, pp. 495–510, 2006.

[11]    M. Parise and S. H. Cannon, “Wildfire impacts on the processes that generate debris flows in burned watersheds,” Nat. Hazards, vol. 61, no. 1, pp. 217–227, 2012.

[14]    J. J. Major, “POST-ERUPTION HYDROLOGY AND SEDIMENT TRANSPORT IN VOLCANIC RIVER SYSTEMS,” Water Resour. Impact, no. March, pp. 10–15, 2003.

[17]    A. Turchi, F. Di Traglia, T. Luti, D. Olori, I. Zetti, and R. Fanti, “Environmental Aftermath of the 2019 Stromboli Eruption,” Remote Sens., no. 12, pp. 1–23, 2020.

4.

Materials and Methods

Chen’s 1983 process was employed. Justify the use of this process versus some other modern processes.

The choice of the Chen's method has been justified in the corresponding section by adding the following text:

“The generalized equation proposed by Chen allows the processing of the most common type of rainfall record (maximum annual rains in 24 $h$), the ones that were available for the Stromboli island. Moreover, the Chen formulation, proved to be suitable for return periods greater than 10 years, is supported by the rainfall-duration and rainfall-frequency coefficients, which allows a best fit to local rain parameters.”

Justify why suspended sediment transport is not considered.

The reasons why the transport in suspension was not considered in our calculations were explained in the corresponding section by adding the following text:

“In this study the suspended sediment transport is not considered in the calculations. Suspended sediment transport is a phenomenon that mainly characterizes large, ancient rivers with low slopes, where it has greater influence if compared with the bottom sediment transport. In the case study of the present work, intermittent currents generated by short duration rains in high slopes are the elements that characterize the hydrodynamic of the study area. Here the bottom transport of fine material is more relevant than the transport in suspension.”

Otherwise very well composed.

5.

Results

Good analysis

6.

Discussion

The discussion is in depth and exhaustive

7.

Conclusions

A good summation of the work in this paper presenting important facts.

8.

Concluding Remarks: Minor write-up

We thank the reviewer for the positive feedback about the manuscript sections mentioned above. The conclusions have been improved also adding some considerations suggested by another reviewer.

Round 2

Reviewer 2 Report

I did not find any significant changes connected with input data needed for numerical modelling, (mainly connected with soil cover properties) . After that the predicative value of the paper is still relatively low.

Even without any numerical modelling we can say that during first years after the fire the surface erosion will be higher, as well rain outflow to the small rivers. But how much depends on correct input data.

Author Response

Response to Reviewer 2 Comment:

I did not find any significant changes connected with input data needed for numerical modelling, (mainly connected with soil cover properties) . After that the predicative value of the paper is still relatively low.

Even without any numerical modelling we can say that during first years after the fire the surface erosion will be higher, as well rain outflow to the small rivers. But how much depends on correct input data.

As we tried to explain in the first stage of the article revision, the software that we used for the simulations of surface runoff and sediment transport (IBER), has already been validated in numerous articles in which it has been proven that, especially for what concerns the surface runoff, the St. Venant equations in 2 dimensions are the best way to represent the surface flow, where the only input parameter that needs calibration is the Manning coefficient, while the rain values are obtained from weather stations present in the study area.

For the transport of sediments, many theoretical and experimental studies show that the critical parameter that controls the material movement threshold is the bottom shear stress (e.j. Chiew & Parker, 2010), which is strongly influenced by the slope of the bottom, the friction angle and particles diameter.

The input parameters used by us to solve the sediment transport equations were taken from a work by Verrucci et al. 2019, in which field analyzes and laboratory studies were carried out aimed at characterizing the sediment. These analysis have not been performed by the authors of this paper but already published in international journals. It remains somewhat difficult for us to understand what is meant by "verified input data". When are the data verified? Do we have to do a sampling to measure geotechnical parameters again? If so, any numerical modeling work would also require a soil sampling phase. This does not seem to be happening.

Furthermore, to support the validity of the method we use, we would like to point out the study by Pinto et al. (2006), which shows a sensitivity analysis of the input parameters for the formulas of sediment transport. The study shows that the key physical properties that control the accuracy of the formulas used and consequently the error in calculating the sediment transport are the speed of the current and the average diameter of the particles, having the speed a greater influence. Among the formulas most used, that of Van Rjin is the most sensitive to the physical properties of the material rather than the limitations of the formula itself. This formula, although present among the IBER options, has been discarded by us. The other formulas are less sensitive to the change in the diameter of the particle and the authors indicate that, if the precise diameter of the material is not known, it is more convenient to underestimate than to overestimate it to obtain a result with the least error.

The current version of IBER works with uniform or quasi-uniform sediment granulometries, in which the size of the granule is characterized by its average diameter, in line with most of the formulations currently used for sediment transport. Obviously, the implementation of specific formulas that take into account the sediment mixtures with non-uniform particle sizes would make the calculation more accurate and in the future, once implemented these functions in the software, we could improve the work.

Finally, we are aware that as a consequence of a fire, a soil inclined to erosion and superficial flow is generated, and this is the hypothesis of the work. The objective is instead to analyze the risk this entails on the inhabited areas of the island and this has been possible with the application of the numerical model, with the aim of giving indications on the basis of national recommendations and therefore providing data for the hazard assessment.

All these considerations have been clarified in the text as follows, with the related bibliographical references that were absent in the previous version of the article:

“According to theoretical and experimental studies [48] the critical parameter that controls the material movement threshold is the bottom shear stress which strongly depends on the sediment grain roughness as well as on the bed morphology  (i. e. the bottom slope, the friction angle and the particle diameter”. Lines 171-174.

“According to Pinto et al. [51] the key physical parameters that influence the sediment transport formulas and consequently the error in calculating the sediment movement are the current speed and the particle average diameter, having the speed the greater influence. According the to the mentioned study, the Van-Rijn formula is the most sensitive to the physical properties of the material rather than the limitations of the formula itself. Considering that the sediment physical parameters used in the present work, and discussed below in this section, derive from a previous study based on Stromboli sediment field and laboratory analysis, the solid flow rate (q_sb) is calculated here using the Meyer-Peter and Müller equation:”. Lines 184-191.