Detecting and Analyzing Land Use and Land Cover Changes in the Region of Al-Jabal Al-Akhdar, Libya Using Time-Series Landsat Data from 1985 to 2017
, Siva K. Balasundram 1,*, Ahmad Husni Mohd. Hanif 1 and Christopher Teh Boon Sung 1Round 1
Reviewer 1 Report
Overall comments
The paper presents an approach to detecting and analyze the LULC spatio-temporal changes in a region of Libya. The authors designed an approach for LULC modelling by using Landsat data and geoprocessing techniques.
Thematically, the study is especially relevant and suits well into the scope of the journal. The manuscript is written in a sound manner and I would reconsider the paper for publication after the major issues have been analyzed and discussed. My comments mostly refer to form, presentation and discussion, and I hope the consideration of them will make the manuscript better readable and more explicit regarding the merits it already has. However, I have some suggestions that may improve the article.
SPECIFIC COMMENTS:
1) Lines are not numbered, which makes the review difficult.
2) I feel that the authors use 'land use' and 'land cover' interchangeably. It is mistake, because these definitions means something else.
Keywords:
3) Please find such words which are not in the title, this way search engines of the web will find your manuscript with higher probability.
Introduction:
4) Third paragraph: How can we confirm these affirmations (1-8 lines)? add missing reference(s)
5) Last paragraph: There is any study that can confirm these affirmations (1-5 lines)?
2.2. Data collection:
6) In reality you are studying LULC changes over 33 years, 1985 and 2017 inclusive.
7) The Landsat 5 TM have a thermal band of 120 meters, the Landsat 7 ETM+ thermal band is 60 meters and the Landsat 8 OLI/TIRS the thermal band is 100 meters and the pixel of the other bands is 30 meters. As such, how did the authors resample thermal (TIRS) band?
8) The authors justify each year in analyze, however, why the authors choose to finish the analysis in 2017 and not in 2018 or even 2019?
9) Last paragraph: How many GCP the authors used? Clarify the % used for training and for validation purposes.
2.3.2. Image classification:
10) For supervise classification how many samples are used and how are they distributed?
11) Is the sample size adequate? Are results significant? Improve this bit adding some more information for discussion of potential limitation and analysis that may help overcome the fact that the sample size is not humongous
12) Why not classify water bodies?
2.3.3. Classification accuracy assessment:
13) Kappa is a very bad way to measure accuracy. Please see “Death to Kappa: birth of quantity disagreement and allocation disagreement for accuracy assessment” (2011). It is more important, for instance, to calculate the error tolerance: See “Automatic Spectral Rule-Based Preliminary Mapping of Calibrated Landsat TM and ETM+ Images” (2006)
3.1 Accuracy Assessment:
14) Table 3, these are the simple classification results, what are the implications of this classification?
15) Last paragraph: Final lines are missing reference(s)
3. Results and Discussion
16) The supervised maximum-likelihood classifier is overcome by other classifiers such as the object-based classifier (OBIA) since it is superior to traditional pixel based classification. At least, the authors should discuss about the use of this classifier regarding others most cited in the remote sensing literature.
17) I suggest the reading of some remote sensing literature that can help clarify some misunderstanding in the manuscript and improve the discussion regarding the use of such data and methods when using Landsat time-series. For example, you can check and cite: https://doi.org/10.3390/rs11091104, https://doi.org/10.1016/j.isprsjprs.2016.03.008, https://doi.org/10.1016/j.rse.2014.01.011
Author Response
Response to reviewer 1 attached.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This article was well written in general and addressed long-term spatio-temporal dynamics of land use and land cover in the region of Al-Jabal Al-Akhdar, northeastern Libya from 1985 to 2017. The aim of this study is clear. It presented a clear workflow for the classification and validation of the LULC maps over a 32-year period using Landsat images. Based on the classified LULC maps, this study also gave an interesting view of deforestation, agricultural land expansion, and urbanization. As a case study of land use/land cover change, it stands well in methodology, results, and discussion. The remote sensing part is well executed and solid while lacks innovative in terms of processing of remote sensing data in the methodology part.
Major comments:
- The abstract should be improved on the quantification part. Please add statistics of the land changed area instead of only change rate percentage.
- 2nd paragraph of Introduction: please review literature about forest transition theory which will help you understand forest dynamics and human activities. I recommend the following three studies as reference:
Rudel, T. K. (1998). Is there a forest transition? Deforestation, reforestation, and development 1. Rural sociology, 63(4), 533-552.
Wang, C., Gao, Q., Wang, X., & Yu, M. (2016). Spatially differentiated trends in urbanization, agricultural land abandonment and reclamation, and woodland recovery in Northern China. Scientific reports, 6, 37658.
- I noticed the authors have collected ground-truthing points in section 2.2. However, in section 2.3.2, they mentioned the other way to get training samples. Please clarify it.
- In section 2.3.3, how many classification models did you create, one pre studied year?
- In the Results and Discussion section, it will be better to divide them into two sections so that you can clearly present the new findings of this study while discussing the spatio-temporal dynamics of LULC and their driving factors (e.g., population change) between this study with other literature.
Author Response
Response to reviewer 2 attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The Authors provided more explanations on the raised issues and modified the manuscript accordingly. I have few minor comments on the revised version:
- Line 319-322: The equations don’t contain any information of the containing variables, clarify the meaning of each of them
- Line 392: Figure 6, please change the color of the UB and BLV classes (like all the other figures have it), they are switched which can lead to confusion.
- Line 709: % is missing after 39
Author Response
Response attached.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The revision meets most of my review comments. But I do suggest considering a standalone discussion instead of mixing the results with the discussion, which will help readers easily understand the drivers of land changes occurred in the region of Al-Jabal Al-Akhdar, Libya.
Author Response
Response attached.
Author Response File: Author Response.docx
