Safety First? Lessons from the Hapcheon Dam Flood in 2020
Round 1
Reviewer 1 Report
The article Safety First? Lessons from the Hapcheon Dam Flood in 2020, presents an interesting analysis of the flood event during August 2020, describes its impacts and performs a simulation of it under other characteristics to compare the impacts and describe what would have happened if they had been chosen by other operating rules of the reservoirs. I consider that there are enough inputs to improve the work, but in its current version it is too long, too many figures and disjointed with respect to what is wanted to describe this work that must be in hand with the objectives: (1) the causes of flooding downstream of the HCD; (2) the main reason for the high outflow; and (3) how floods can be avoided. Under this context I suggest major revision of this work to be accepted in Sustainability. As English is not my mother language, I suggest a review by the editors.
Some general recommendations for the document are:
- There are too many figures and many of them are not very explanatory. I suggest sending them to Annexes or as additional material; and in some cases join them as one.
- I suggest reordering the document according to the following structure:
- Introduction
- Materials and Methods
- Describe the data used in the analysis of rainfall and flows extremes, period, etc. And how will it be focused having both series different periods
- The methodology must be consistent with the stated objectives so that the paper gains understanding.
- How will the HEC-RAS hydraulic model be validated, with the events ?
- Describe in detail the comparison that will be made with (a) Maemi and (b) Sanba, for example, place in the operating rules that it was of different?
- Describe how it will compare to hydraulic simulation under other operating rules
- I suggest a flowchart of the methodology to make it clearer
- The flood event of August 2020 is quite extensive, I suggest reducing this section and focusing on the impacts caused and the flooded areas that are described in the document
- The results must be described according to the flowchart presented. I suggest focusing on describing them in this order:
- Analysis of hydrological extremes (rains and flows); reduce the figures and tables only leave the return periods and the value reached during the event; and can be used to place the years of the events (a) Maemi and (b) Sanba in the same figure.
- The Dam Management Analysis section should be joined to that of (a) Maemi and (b) Sanba there is not much to be gained by having them separate and the figures would be decreased especially figures 12, 13 and 14 should be joined.
- Simulation Results in Operating HCD, it would be interesting in this section to include the 2020 event for comparative purposes.
- Simulation for Downstream, this section is interesting, but a figure of the flood inundation map of the hydraulic simulation in 2D similar to that shown in Figure 7a should be presented and compared with what happened
- The discussion of the document should include overall suggestions related to the hydrological and hydraulic analisys outputs, not only about the evento facts.
- The conclusions section should focus on the stated objectives and this is not the case with what is presented, I suggest redoing it.
Some minor comments:
- Figure 1 Include the elevation map and the direction of the river (South to North or vice versa?) Show north arrow in the map
- Description of the 2020 Flood Event in the HCD Area. I suggest to summarize it is very extensive
- Figure 3. Placing the maps with the same rainfall rates (color bar) for comparison purposes
- Figure 6a improve the line that identifies RWL and FWL is not very clear
- P8-169 cite Hapcheon sports in Figure 7ª
- Figure 7a, which is blue and light blue. This figure is key to understanding the entire document. I suggest improving it.
- Figure 8. I suggest placing the references of the photos and sending them to Annexes
- P9 177-183 Place the spatial references of Maeho village and Naecheon in figure 7ª
- Table 2. Indicate that the Index is related to Figure 7ª
- P10-219 to P11-231 I suggest sending to the Annexes
- Q11- 232 was this used at work? The data used and the period used are not clear either. Describe the time period used
- P11-255 HEC RAS ​​is more of a hydraulic model than a hydrological one. How did it come to be used as a rainfall-runoff model?
- Figure 9 and 10. I suggest unify figures 9 and 10 into one since this way the extremes in the 2 meteorological stations could be compared and I don't see any sense in the equation in each sub-figure, I suggest removing it. I suggest sending it later to annexes since Table 4 and Figure 11 support this analysis well.
- Figure 11. It would be nice to include the return periods for Maemi and Sanba.
- P15-319 “Further flood frequency analysis must be performed to investigate the cause of the 2020 flood event”. I do not agree with this paragraph since that is the objective of this work.
- Flood Frequency Analysis of Inflow. Explain the weaknesses of having different periods of rainfall and peak flow data.
- Figure 12. It is clearly noted that the outflow in 2020 was too much compared to other years and being that part described qualitatively, it would be good to describe in detail why the competent entity released such magnitude of flow in the discussions section.
- Figure 13. Placing the (a) Maemi and (b) Sanba events in this figure will make it easier to see what happened during these extreme events.
- Figure 16. Include comparative maps of inundation flood with what happened in the event and what comes out of the hydraulic simulation.
- I suggest reviewing the bibliography according to what the journal requests, but for example citations 39 to 43 are incomplete, there is no doi or web address.
Author Response
See the attached file for the responses of the comments from this reviewer.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors
please need to revise the abstract and check English for all the manuscript
please revise the reference list
Hydrologic alteration at the upper and middle part of the Yangtze river, China: towards sustainable water resource management under increasing water exploitation
Long-Term Trends and Seasonality Detection of the Observed Flow in Yangtze River Using Mann-Kendall and Sen’s Innovative Trend Method
please check the whole manuscript before resubmit
Author Response
See the attachment for the responses to the comments from this reviewer.
Author Response File: Author Response.pdf
Reviewer 3 Report
Figure 1 does not have geographic coordinates or scale. This makes it difficult to find the location of the dam in the basin, for those of us who are not familiar with the geography of South Korea.
Lines 67-68: specify geographic coordinates (latitude, longitude)
Line 120. Was this precipitation event extraordinary? in one day it precipitated 10% of the total for a year? Is intense rainfall in the study area frequent this time of year?
The authors could describe the event a little better on a regional scale. They could use NOAA data on a global scale or some synoptic description of the area for those days (or Weather Chart·Images):
https://earth.nullschool.net/#2020/08/08/0100Z/wind/surface/level/overlay=precip_3hr/orthographic=-234.73,38.50,1242/loc=128.322,35.369
Was the precipitation correctly forecast by the responsible agencies? (thus paragraph L499 of the discussion can be better understood).
L124-125: the 7 stations used must be identified. Do they include the two mentioned above?
and where is figure 2? and 4? 5? ...
L177-182: How many dwellings and inhabitants are in Maeho Village and in Naecheon village? Figure 1 should show all the locations mentioned in the text. Where are these sites located?
At the end of section 2.1 (study area), a description of the villages in the basin affected by the flood could be added.
L193. Index are the labels of figure 7?
L279-280. This phrase should be in the methodology. Where were the data from these weather stations obtained? Korea meteorological agency?, data is online for download?
Author Response
See the attachment for the responses to the comments from this reviewer.
Author Response File: Author Response.pdf
Reviewer 4 Report
The paper makes a detailed analysis of the accident causes of Hapcheon Dam Flood in 2020, which has a good enlightenment to the dam scheduling work. The paper basically meets the requirements for publication, but it can be improved in some small details.
- “Dam construction is one of the major tools to protect and mitigate floods.” (line 39-40) appears very abruptly. Merging it with the first sentence may be better.
- The title of section 2.2 is not accurate enough. The content of This section is not just about flood prevention.
- It is mentioned in Section 2.3.1 that the data are from 7 weather stations, which should be marked at least in Figure 1
Author Response
See the attachment for the responses to the comments from this reviewer.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The paper has been correctly improved and the revisions are correct