the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Flood hazard mapping and disaster prevention recommendations based on detailed topographical analysis in Khovd City, Western Mongolia
Abstract. The impacts of climate change manifest heterogeneously across regions, and in Khovd City, a semi-arid area in Western Mongolia, the escalating threat of flooding is evident through the occurrence of 10 flash floods in the last 30 years. The risk zone, encompassing rivers and flash floods, endangers ca. 32,000 residents, with 750–1,800 traditional nomadic dwellings (gers) located on the floodplain of the Buyant River during summer. There is a risk of flash floods in the eastern part of Khovd City from the mountains, while the western part is at a higher risk of flooding from the Buyant River. This paper aims at assessing flood hazards through a detailed topographical survey conducted using an Unmanned Aerial Vehicle (UAV). 15,206 aerial photos were collected in Khovd City using the UAV and measured by Real-Time Kinematic (RTK) on 22 Ground Control Points (GCPs). A Digital Elevation Model (DEM) with a resolution of 2.7 meters was generated from the aerial drone mapping data, enabling surface morphology, hydrological and eight-direction pour point model analysis using a Geographic Information System (GIS). The resulting flood hazard map revealed 4 flood risk areas based on flood flow direction and topographical features. Recommendations for local govern and residents include enhancing flood protection facilities for flood disaster prevention on flood risk zones.
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RC1: 'Comment on nhess-2024-91', Anonymous Referee #1, 18 Jul 2024
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Review to Flood hazard mapping and disaster prevention recommendations based on detailed topographical analysis in Khovd City, Western Mongolia, Author(s): Narangerel Serdyanjiv et al., MS No.: nhess-2024-91
general comments
In the study “Flood hazard mapping and disaster prevention recommendations based on detailed topographical analysis in Khovd City, Western Mongolia”, authors present rainfall runoff maps based on digital elevation data derived from UAV flights.
Unfortunately, the study lacks novelty and evaluations lack scientific quality. Results are of interest to local decision-makers but do not contribute scientifically enough on their own. Other than stated in the introduction, riverine flooding is not accounted for, but only surface runoff. Further, the areas at risk are not specified or classified, which would be of interest to decision-makers, and first responders, and support the adaption process. I would advise you to continue and expand your analysis, because it seems, that additional data and information are available, but were not used.
specific comments
An evaluation scheme for the risk areas including classification would be helpful to clarify the identified risk areas.
As further field data exist (geological, morphological, hydrological?, maybe critical infrastructure?), I recommend conducting further analysis.
Could the study benefit from evaluating and including the local interviews (shown in Figure 2)? If not, please explain, why the locations of interviews are shown in Figure 2.
Would a multi-hazard evaluation be possible, which includes reconstructed or modelled fluvial inundation?
Line 135ff: it is unclear to me, when the Alos Palsar DEM satellite data and when the UAV-generated DEM was used in your study, or how you combined the two DEMs
Line 174: is it possible to show the alluvial fan on a map?
Line 180: please specify “relatively slow”; e.g., please add significant values
Figure 4: could you additionally show inundation depths?
Line 190: how is the grouping of the cells done, and for what purpose?
- Is the bed or the water surface area of ditches and rivers shown in the DEM? If not, does the study benefit from embossing the bed level to the DEM?
- How are flow directions further evaluated to overall evaluate the risk posed by flash floods?
98-105: please consider moving the background information to the introduction/background
Line 147-171: please move to the description of the study area
Lines 201-204: please consider moving the background information to the introduction/background
Lines 212-223: Please provide further information on the sedimentological data you mention (methods, results, consideration in the study). The section belongs to the discussion. Please provide the climatologic data, you are referring to.
Lines 225 to 242 & 246-253: The section covers parts, that belong to the introduction, study area, and discussion. Please provide the corresponding results, and move sections.
Line 268: it is unclear how areas were determined. What are uncertainties? How much higher is the risk compared to other areas?
Fig 9: how does the hazardous flow direction differ from the general flow direction?
Recommendations are too general. Please link them more closely to your results
technical corrections
could you please specify the unpublished literature (e.g., cite the publications as “under review”, if applicable)
Figure 1: Location of pictures is not marked on the map
Line 80 ff: km2 must be km²
Line 91: please check the line break at the end.
Figure 2: Please change /xx/ to (xx)
Table 1: the information seems a bit excessive. Could you remove parts of it, by referring to the UAV you used?
Line 141: Hiishade must be Hillshire
Line 141 ff: (Fill-Flow-direction-Flow accumulation-Stream order-Flow length-Watershed-Basin-Snap pour point and others) commas are missing
Figure 5 and Figure 7: the dashed red line is missing in the legend
Citation: https://doi.org/10.5194/nhess-2024-91-RC1
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