Comparison of Rain-Driven Erosion and Accumulation Modelling of Zafit Basin on Earth and Tinto-B Valley on Mars

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments:

- please justify the usefulness and the potential of this work if it is difficult to compare results from Earth and Mars because of differences in topography (normalized slope distribution, area of sample sites, bedrock...)

-the text and figures of the manuscript needs some rearrangement:

- in Methods section, the applied equations should be ordered as they are mentioned in the text

- the positioning of figures and tables should be as close as possible to the mentioning in the text

 

Specific comments:

- Line14: please correct precipitation-based

- Line77-82: the section may be moved to Line119, after the descripton of the study area

- Figure1: please emphasise that the Tinto B is the study area of the present study

- Line177: the formula of Kt is missing, it is just decribed in the text

- Line207: please clarify, what does "above listed" means? There is not a list above this section.

- Table2: what does * means (at fow depth)? please clarify; peak discharge values are missing from the table

- Line320: please check the correct term: carbonaceous or calcareous sedimentary rocks?

 

Author Response

please check attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a good paper elucidating differences in physical erosion and sedimentation on Mars versus Earth. It is worth publishing after moderate revision.

I am struck by the choice of median grain size as 1 mm (=sand l.145), which I think is inappropriate for desert regions on Earth with loess and dust from clayey soils. Martian soils were also dominated by silt, and their clay fraction included a lot of amorphous material rather than mineral clay (Retallack, G.J., 2014. Paleosols and paleoenvironments of early Mars. Geology, 42(9), pp.755-758). I do not think 1 mm appropriate as median grain size for Martian basalt or Earth sediments other than sandstone. Some alternative calculations with various median grain sizes would be interesting.

I am also wondering about the slope angle distribution on Earth versus Mars mentioned as similar (l 310). They do not look similar to me, as the pattern is so much more diffuse on Earth but more channelized on Mars. An actual plot would be useful.  Slope angle distributions are controlled by soil thickness: probably much thinner on Mars than Earth (see especially Dietrich, W.E. and Taylor, P.J., 2006, The search for topographic signature of life, Nature 439, 411-418). They could also be due to diffuse precipitation on Earth versus local ice-melt origin of water on Mars. What exactly is the evidence that it ever rained on Mars? These issues deserve more discussion.

I also question whether Mars should be modeled as all high-density basalt as opposed to low-density sedimentary rock for Earth (l.318-319). Both areas have some soil that is friable on top of bedrock, and that thickness is critical (see Dietrich and Taylor 2006 op cit). Desert badlands such as Zafit have at least 20 cm of loosened soil above, as I well know from excavating into them to study bedrock.

l.14 Should this be precipitation-based? Rather than bases

l.34-35  Already and previously are redundant: delete one.

l.361 Is ores the right word here? Ore is a material enriched in a valuable commodity wuch as gold or copper.

Author Response

please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Kindly see the attached file. 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Maybe the present version can benefit from the English service. 

Author Response

Response to Reviewers’ questions on the manuscript universe-3380848

Referees’ comment with black, authors’ reply with blue colour

 

 

Reviewer 2

 

In this study, the authors presented a comparative study of fluvial erosion and deposition processes in a terrestrial and a Martian watershed. Using an enhanced steady-state erosion and accumulation model, the research applies precipitation data from the arid Zafit basin in Israel to simulate hydrological and geomorphological parameters for the Martian Tinto-B valley. Key findings indicate significant differences in erosion and accumulation rates between the two environments, largely influenced by variations in gravity, sediment density, and slope angles. While flow velocities were found to be similar on both planets, transport capacity and erosion rates were considerably higher on Earth. The study underscores the utility of terrestrial analogs in reconstructing Martian paleoclimates and surface evolution and highlights the need for further model refinement to incorporate unsteady-state dynamics and long-term geomorphic processes. This paper is written-well. Based on reviewer’s opinion, the present form of manuscript need a revision before publication. There are some comments which are given below:

1. Make the abstract simpler by providing a concise summary of the main findings, methods, objectives, and consequences. A wider audience will find it easier to access as a result.

The abstract was shortened and made somewhat more general: “While fluvial features are plentiful on Mars and offer valuable insights into past surface conditions, there is still some debate on the climatic conditions inferred from these valleys, like precipitation and surface runoff discharges. Model-based estimations have already been applied to several Martian valleys, but there has been limited exploration of the related numerical estimations. This work applies an improved precipitation-based, steady-state erosion/accumulation model to a Martian valley and compared it to a terrestrial Mars analog dessert catchment area. The simulations are based on a previously observed precipitation event to estimate the fluvial related hydrological parameters like, flow depth, velocity and erosion/accumulation processes in two different but morphologically similar watersheds. Moderate differences were observed in the erosion/accumulation results (0.13/-0.06 kg/m²/s for Zafit (Earth) and 0.01/-0.007 for Tinto B (Mars)). The difference is probably related to the lower areal ratio of surface on Mars where the Shield factor is enough to trigger sediment movement, while in the Zafit basin, there is a larger area of undulating surface. The model could be applied to the whole surface of Mars, using grain size estimation from the global THEMIS dataset, grain size value artificially increased above the observed one, and decreased hypothetic target rock density tests demonstrated the model works according to theoretical expectations and useful for further development, The findings of this work indicate further testing of similar models on Mars are needed, as well as a better general analysis of the background geomorphological under-standing of surface evolution regarding slope angles. “

 

2. Give additional background on the importance of contrasting the basins on Earth and Mars. Emphasize the uniqueness and particular contributions of this study in relation to previous research.

The following sentence was implemented to the and of the Introfuction abut the aim of this work: “An important aspect of this work is while most earlier publications focused on the morphological similarity of Earth and Mars based fluvial systems, here the comparison is focused on model based numerical calculations to adapt Earth based equations to Martian conditions.”

 

3. A thorough comparison with earlier models or research is absent from the manuscript. Include a section outlining the shortcomings of previous research and how this study overcomes them.

The earlier part of the Introduction starting with “Existing models aim to reconstruct river transport focusing on discharge…” was expanded by the specific mention f the main differences between tis and the earlier models: „One of the main differences between this and earlier works is that here the modelling of fluvial process is based on erosion/accumulation related calculations, and goes beyond the solely estimation of discharge.“

 

4. Give a more thorough explanation of the model's assumptions, parameter choices, and validation procedure. Explain the handling of uncertainties, such as the estimates of precipitation on Mars.

We added a new reference here, and the exact values of the critical Shield’s parameter was given to us directly from the author of the mentioned article (Maarten G. Kleinhans

Beyond the above listed aspect a new subchapter was introduced on the uncertainties and limitations of this model including parameter selection:

4.1 Feasibility and limitations of the model

 

Testing the model’s performance for different input parameters, the role of density change and sediment size change were evaluated in derails, especially how the Transport Capacity and Erosion/Accumulation Rate values accordingly. For grain size permutation, no significant difference was found but the small change happened according to the expectations: the decreasing grain size caused increased erosion / accumulation rates as smaller grains are more easily transported. These findings suggest the model is realistic, and if in the future better grain size estimation would be available using remote sensing correlated in-situ data, improved modelling would be available for the whole Martian surface.

Regarding the change of density of target rocks for the Martian sample area (Tinto B), decreased density produced substantial  increase in Transport Capacity, which are typical of more porous rocks. This significant increase also coincides with expectations, further confirming the reality of the used model approach. This also indicates in the future the weathering state and related density of target rocks if better known for Mars could be better implemented to the modelling, supporting the emergence of better erosion / accumulation rates.

Limitations and uncertainties of the model come from two groups of sources. 1. Accuracy of input parameters is limited by the observational possibilities and currently available instrument for Mars. Improved remote sensing data is expected to give better DTMs soon, while improvement of target density knowledge is less expected, as for global dataset improved thermal inertia analysis requires both higher spatial resolution and temporal density of measurements, what are difficult to gain, and many further remote sensing data - ground truth measurement pairs by landers is difficult to fain as it is not realistic to land at a wide range of surface types soon. 2. Uncertainty comes from the poorly known micro-scale physical processes, e.g. shield parameters, role of flocculation (grain grouping) by any unique water chemistry, or specific vortex behavior under reduces gravity could be improved by laboratory tests on the Earth, where a great problem regarding Mars relevance is to estimate the corresponding values under the reduced Martian gravity, however theoretical argumentation might help.

5. Give a thorough description of how important measurements, such flow depth and transport capacity, affect our comprehension of the climate and surface development of Mars.

The following new paragraph has been implemented to the end of the former Discussion (before the new subsection, see below):

“Considering the application of the model for climate and environmental reconstruction of past Martian conditions, especially for the Noachian and Noachian/Hesperian transition where waterflows and related transport were widespread the following are relevant. The better information on erosion and sedimentation could help to constrain the ancient paleo-discharge values as the mass of transported sediment and the volume of material have been eroded away from channels depressions could be measured. If the erosion process could be better characterized in the future by improved modelling, the maximal discharge estimation could support to separate the temporal emergence of water source: sudden rainfall or continuous “light” raining events happened. In the case of more moderately sudden ice melting (like hot ejecta emplacement on a formerly deposited snow or ice sheet) could be also better reconstructed and understood.“

 

6. Describe potential avenues for future research, such as creating unsteady-state models and conducting experiments on different Martian terrains. Talk about the possibility of including more observational data.

The end of the Conclusion, was modified with the following sentences, to expose the future updates and changes of the presents model

“At the present stage, the model is only capable of considering so-called steady-state conditions, which can be utilised to simulate one-off, short-timescale events. Long-term improvements include the development of a model that can also investigate unsteady conditions, i.e. conditions that are in constant change over the simulated time. The implementation of such studies will facilitate the investigation of the formation of Martian river valleys and the direct study of paleoclimatic conditions on the red planet. Unsteady models possess the capacity to study long-term (up to several thousand years) changes in a dynamic manner. It is envisaged that the development of the model will not only study precipitation-induced erosion, but also the erosion of ice melted during Martian volcanic activity and subsequent run-off in the form of flash floods. These future developments will facilitate the acquisition of a more precise depiction of the evolution of the Martian surface and could also contribute to the study of the morphology of the Earth's watersheds.”

 

7. Make the language more professional and fluid. Fix any grammatical errors and awkward wording, particularly in the abstract and conclusion sections.

Thank you for the suggestion, the language as improved please see the track changes modifications in the manuscript.

 

8. How are the quality and comparability of the results impacted by the Digital Terrain Models' spatial resolution (30 m for Earth and 50 m for Mars)?

A substantial corpus of satellite data on Mars is available, encompassing terrain models, spectral surveys and high-resolution images. However, the quality of these data is often suboptimal. For extensive regions, the most advanced terrain models are those derived from the HRSC (High Resolution Stereo Camera) instrument, with a resolution ranging from 50 to 200 metres. The resolution of this Digital Terrain Model (DTM) is the closest to the 30-metre-per-pixel resolution of the SRTM (Shuttle Radar Topographic Mission) topography models commonly used on Earth. The quality of the SRTM data was not directly degraded during the research, as the intention was not to influence the results in any way. The almost similar spatial resolution of Earth and Mars based DTM supported the work and comparison, providing similar scale of uncertainties, generalization etc.

 

9. How was the threshold for the Shields parameter (\tau*_crit = 0.03) established for Martian conditions, and does it sufficiently take into consideration variations in gravity and sediment characteristics?

It is evident that a reliable source for a critical Shield parameter for the Zafit area is not available at this time. Therefore, the value derived from the Mars sample area has been applied to the terrestrial sample area.

We added a new reference here, and the exact values of the critical Shield’s parameter was given to us directly from the author of the mentioned article (Maarten G. Kleinhans

 

10. For the terrestrial Zafit basin, were any validation studies conducted to compare the model predictions with field data or alternative modeling techniques.

In the context of the Zafit (terrestrial) study area, the available hydrological measurements (water yield) are derived from a model-based approach. It is important to note that comparisons between the results of one model and those of a model partially presented in another study area are inherently problematic. Consequently, this aspect was not addressed in the research.

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The study references the use of a "enhanced precipitation-based, steady-state erosion/accumulation model," although it lacks details regarding the model's validation or calibration.

Information regarding the assurance of the model's accuracy, specifically in Martian conditions, is absent.

The outcomes indicate the necessity for additional testing on Mars, although they do not address the particular limits of the model or the datasets employed. This generalization jeopardizes the nuanced intricacies of Martian geomorphology.

The introduction briefly addresses the areal ratio of undulating surfaces but fails to explore additional elements that may affect erosion and accumulation on Mars, including regolith composition, atmospheric pressure, and historical hydrological activity.

Moreover, the introduction seems very insufficient on the motivation of the study, the need for the study and the limitations of the previous studies. The study could benefit from referencing prior research on Mars' surface evolution and settlement planning, such as Mukundan et al. (2023) and Mukundan and Wang (2022). These works discuss the geomorphological and hydrological challenges in establishing self-sustaining settlements on Mars, which are directly relevant to understanding fluvial activity and erosion/accumulation processes. Incorporating these studies could strengthen the context of the findings and highlight their potential implications for future Martian colonization efforts. Specifically, linking the current study's results to settlement feasibility in regions with significant erosion/accumulation differences might offer valuable insights such as:

 Mukundan, Arvind, Akash Patel, Bharadwaj Shastri, Heeral Bhatt, Alice Phen, and Hsiang-Chen Wang. "The Dvaraka Initiative: Mars’s First Permanent Human Settlement Capable of Self-Sustenance." Aerospace 10, no. 3 (2023): 265.

 

Author Response

Moreover, the introduction seems very insufficient on the motivation of the study, the need for the study and the limitations of the previous studies. The study could benefit from referencing prior research on Mars' surface evolution and settlement planning, such as Mukundan et al. (2023) and Mukundan and Wang (2022). These works discuss the geomorphological and hydrological challenges in establishing self-sustaining settlements on Mars, which are directly relevant to understanding fluvial activity and erosion/accumulation processes. Incorporating these studies could strengthen the context of the findings and highlight their potential implications for future Martian colonization efforts. Specifically, linking the current study's results to settlement feasibility in regions with significant erosion/accumulation differences might offer valuable insights such as:

 Mukundan, Arvind, Akash Patel, Bharadwaj Shastri, Heeral Bhatt, Alice Phen, and Hsiang-Chen Wang. "The Dvaraka Initiative: Mars’s First Permanent Human Settlement Capable of Self-Sustenance." Aerospace 10, no. 3 (2023): 265.

Thank you for the suggestions to enlarge the context of the work, the following part has been implemented the following part in the Introduction section: “It is worth mentioning that the reconstruction of fluvial processes on Mars plays an important role to better understand the “whole” geological history and interaction between various agents like climate and surface evolution trends [17], [18]. The modelling aspects could provide input and suggestions to better optimize the future colonization and human settlement localization for the next decades [19] and. [20]”

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

No more further comments. The manuscript can be published in the present form. 

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have made significant changes to the article, it can be published.