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Rahim MA, Al Assi A, Mostafiz RB, Friedland CJ. Effects of damage initiation points of depth-damage function on flood risk assessment. NPJ NATURAL HAZARDS 2024; 1:6. [PMID: 38720873 PMCID: PMC11078111 DOI: 10.1038/s44304-024-00004-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 02/01/2024] [Indexed: 05/12/2024]
Abstract
The flood depth in a structure is a key factor in flood loss models, influencing the estimation of building and contents losses, as well as overall flood risk. Recent studies have emphasized the importance of determining the damage initiation point (DIP) of depth-damage functions, where the flood damage is assumed to initiate with respect to the first-floor height of the building. Here we investigate the effects of DIP selection on the flood risk assessment of buildings located in Special Flood Hazard Areas. We characterize flood using the Gumbel extreme value distribution's location (μ) and scale (α) parameters. Results reveal that average annual flood loss (AAL) values do not depend on μ, but instead follow an exponential decay pattern with α when damage initiates below the first-floor height of a building (i.e., negative DIP). A linear increasing pattern of the AAL with α is achieved by changing the DIP to the first-floor height (i.e., DIP = 0). The study also demonstrates that negative DIPs have larger associated AAL, thus contributing substantially to the overall AAL, compared to positive DIPs. The study underscores the significance of proper DIP selection in flood risk assessment.
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Affiliation(s)
- Md Adilur Rahim
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA USA
- Engineering Science Program, Louisiana State University, Baton Rouge, LA USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA USA
| | - Ayat Al Assi
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA USA
- Bert S. Turner Department of Construction Management, Louisiana State University, Baton Rouge, LA USA
| | - Rubayet Bin Mostafiz
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA USA
| | - Carol J. Friedland
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA USA
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Al Assi A, Mostafiz RB, Friedland CJ, Rohli RV. Theoretical Boundaries of Annual Flood Risk for Single-Family Homes Within the 100-Year Floodplain. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH 2024; 18:29. [PMID: 38495553 PMCID: PMC10943154 DOI: 10.1007/s41742-024-00577-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 03/19/2024]
Abstract
Special flood hazard areas (SFHAs), defined as having an annual probability of occurrence of 1 percent or above, are used by U.S. Federal Emergency Management Agency (FEMA) to demarcate areas within which flood insurance purchase is required to secure a mortgage. However, quantifying flood risk within SFHAs can be challenging due to the lack of modeled flood depth data for all return periods. To address this issue, this research quantifies flood risk indicated by average annual loss (AAL) within the A Zone-the subset of the SFHA where wave heights can potentially range from 0 to 3 feet. The methodology resolves the Gumbel quantile function for four distinct flooding cases (i.e., locations flooded at return periods exceeding 1.58-, 10-, 25-, and 50-year return period events) and generates synthetic flood hazard parameters for these cases within the 100-year floodplain, as well as with additional elevation above the base flood elevation (BFE), known as freeboard, for single-family homes with different attributes. The results indicate that for single-family homes in the A Zone, with the lowest floor elevated to the BFE, the AAL ranges from 0.3 to 1 percent of the building replacement cost value. Adding one foot of freeboard reduces flood risk by over 90% if the annual flood risk is between the minimum and 25th percentiles and the 100-year flood depth is less than two feet. The demonstrated approach helps enhance flood resilience in the A Zone, demonstrating the feasibility of proactive measures to protect communities. Supplementary Information The online version contains supplementary material available at 10.1007/s41742-024-00577-7.
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Affiliation(s)
- Ayat Al Assi
- Department of Biological and Agricultural Engineering, LaHouse Research and Education Center, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 USA
- Bert S. Turner Department of Construction Management, Louisiana State University, Baton Rouge, LA 70803 USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA
| | - Rubayet Bin Mostafiz
- Department of Biological and Agricultural Engineering, LaHouse Research and Education Center, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA
- Department of Oceanography & Coastal Sciences, College of the Coast & Environment, Louisiana State University, Baton Rouge, LA 70803 USA
| | - Carol J. Friedland
- Department of Biological and Agricultural Engineering, LaHouse Research and Education Center, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 USA
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA
| | - Robert V. Rohli
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA
- Department of Oceanography & Coastal Sciences, College of the Coast & Environment, Louisiana State University, Baton Rouge, LA 70803 USA
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Al Assi A, Mostafiz RB, Friedland CJ, Rahim MA, Rohli RV. Flood risk assessment for residences at the neighborhood scale by owner/occupant type and first-floor height. Front Big Data 2023; 5:997447. [PMID: 36700139 PMCID: PMC9868865 DOI: 10.3389/fdata.2022.997447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 12/12/2022] [Indexed: 01/11/2023] Open
Abstract
Evaluating flood risk is an essential component of understanding and increasing community resilience. A robust approach for quantifying flood risk in terms of average annual loss (AAL) in dollars across multiple homes is needed to provide valuable information for stakeholder decision-making. This research develops a computational framework to evaluate AAL at the neighborhood level by owner/occupant type (i.e., homeowner, landlord, and tenant) for increasing first-floor height (FFH). The AAL values were calculated here by numerically integrating loss-exceedance probability distributions to represent economic annual flood risk to the building, contents, and use. A simple case study for a census block in Jefferson Parish, Louisiana, revealed that homeowners bear a mean AAL of $4,390 at the 100-year flood elevation (E 100), compared with $2,960, and $1,590 for landlords and tenants, respectively, because the homeowner incurs losses to building, contents, and use, rather than only two of the three, as for the landlord and tenant. The results of this case study showed that increasing FFH reduces AAL proportionately for each owner/occupant type, and that two feet of additional elevation above E 100 may provide the most economically advantageous benefit. The modeled results suggested that Hazus Multi-Hazard (Hazus-MH) output underestimates the AAL by 11% for building and 15% for contents. Application of this technique while partitioning the owner/occupant types will improve planning for improved resilience and assessment of impacts attributable to the costly flood hazard.
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Affiliation(s)
- Ayat Al Assi
- Bert S. Turner Department of Construction Management, Louisiana State University, Baton Rouge, LA, United States,LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA, United States,Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States,*Correspondence: Ayat Al Assi ✉
| | - Rubayet Bin Mostafiz
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA, United States,Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States,Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA, United States
| | - Carol J. Friedland
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA, United States,Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States
| | - Md Adilur Rahim
- LaHouse Resource Center, Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA, United States,Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States,Engineering Science Program, Louisiana State University, Baton Rouge, LA, United States
| | - Robert V. Rohli
- Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, United States,Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA, United States
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