An integrated modelling approach to evaluate the impacts of nature-based solutions of flood mitigation across a small watershed in the southeast United States
Abstract. Floods are among the most destructive natural hazards in the world, posing numerous risks to societies and economies globally. Accurately understanding and modeling floods driven by extreme rainfall events has long been a challenging task in the domains of hydrologic science and engineering. Unusual catchment responses to flooding cause great difficulty in predicting the variability and magnitude of floods, as well as proposing solutions to manage large volumes of overland flow. The usage of Nature-Based Solutions (NBS) has proved to be effective in the mitigation of flood peak rate and volume in urban or coastal areas, yet it is still not widely implemented due to limited knowledge and testing compared to traditional engineering solutions. This research examined an integrated hydrological and hydraulic modeling system to understand the response of an at-risk watershed system to flooding and evaluate the efficacy of NBS measures. Using the Hydrologic Engineering Center Hydrologic Modeling System and River Analysis System (HEC-HMS and HEC-RAS) software, an integrated hydrologic-hydraulic model was developed for Hurricanes Matthew (2016) and Florence (2018) driven floods across the Little Pee Dee-Lumber Rivers watershed, North and South Carolina (the Carolinas), USA. The focus was on Nichols town, a small town that has been disproportionately impacted by flooding during these two hurricane events.
Different NBS measures including flood storage ponds, riparian reforestation, and afforestation in croplands were designed, modeled, and evaluated. Hurricane Matthew's flooding event was used for evaluating the NBS scenarios given its high simulation accuracy in flood inundation compared to the less accurate results obtained for Hurricane Florence. The scenario comparison evidenced that large-scale natural interventions, such as afforestation in croplands, can reduce the inundated area in Nichols town by 8 % to 18 %. On the contrary, the smaller-scale interventions such as riparian reforestation and flood storage ponds showed a negligible effect of only 1 % on flood mitigation.
Betina Ines Guido et al.
Status: final response (author comments only)
CC1: 'Comment on nhess-2022-281', Adriana - Maria Constantinescu, 06 Mar 2023
- AC1: 'Reply on CC1', Betina Guido, 22 Mar 2023
RC1: 'Comment on nhess-2022-281', Anonymous Referee #1, 10 Apr 2023
- AC2: 'Reply on RC1', Betina Guido, 03 May 2023
RC2: 'Comment on nhess-2022-281', Anonymous Referee #2, 13 Apr 2023
- AC3: 'Reply on RC2', Betina Guido, 03 May 2023
Betina Ines Guido et al.
Betina Ines Guido et al.
Viewed (geographical distribution)
The article is well written and structured, providing valuable data and discussion, however, the following should be considered:
The article present o very good mix of methods to evaluate the impact of NBS for flood mitigation. However, a larger relevance of the study should be considered. The entire article is too much focused on the US and the relevance of the study should be reference to other areas in the world with similar problems or where similar solution may apply. Add appropriate paragraphs in the article sections – intro, discussion, conclusions.
Please provide references for all the methods you mention in the Method section.
Introduction – see general comments
Row 107 – add year when maximum discharge was recorded and reference.
Fig 1 – Add name of Atlantic Ocean
Table 2 – add a column with dates (the date is essential metadata for any environmental data).
Line 173-174 – provide references for the methods
Line 183 – ‘has been widely used around the world for catchments of varying sizes’ provide refences
Line 193 – provide reference for the method
Lines 198- 202 – can you provide an estimate of the affected areas in km2 for by each hurricane?
Line 279 – ‘According to the literature,’ provide all appropriate references
General comments – of there is no Discussion section, then the results should be discussed and put in the larger context – why this study is relevant for the US and other areas in the world, what are the limitations of the study, most important results and how they can be used in other areas, or in real practice, etc.
Line 443 – ‘However, still, 38% of the town is at risk of flooding even when afforestation was implemented largely in the model.’ It would be useful for the reader to have an idea about why that is? Can you explain… Is it slope exposure, relief, where the forested areas are placed in relation to town area, most exposed areas to flooding, etc?
See comments above – wider relevance of the study; comparison with other similar studies would be very useful. Also, a quantification of the storage capacity of the forested area would be useful and would add greatly to the current discussion.
Structure: Well structured and well presented
Overall relevance of the study: good (see general comments).
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