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Rising sea levels have increased flood risk in coastal communities on both the east and west coasts of the USA. The goal of this analysis is to approximate flood defense costs from cyclonic flooding as a partial means to evaluate the resilience of coastal communities. Storm surge models were previously constructed via an established approach to represent historical and future coastal Louisiana landscapes and associated flood patterns. Coastal flooding was also previously simulated via a suite of 14 hurricanes. Approximate levee heights surrounding Lafitte, Louisiana, are calculated from the surge and wave output of Hurricane Isaac, the predominated hurricane in the Lafitte area for all years examined (NAVD88, m): 1.68 (1930), 2.92 (1970), 3.30 (1990), 4.82 (2010), 5.93 (2030), 6.57 (2050), 7.16 (2070), 7.70 (2090), and 8.22 (2110). Approximate costs per person are also calculated (2010 USD): $49,500 (1930), $41,400 (1970), $37,500 (1990), $181,600 (2010), $223,600 (2030), $247,800 (2050), $269,900 (2070), $290,100 (2090), and $309,800 (2110). The Gulf of Mexico (GOM) migrated 7.4 km inland within the Louisiana Barataria coastal basin between 1973 and 2010. For each person in Lafitte, flood defense costs increased approximately (2010 USD) $19,000 per person per kilometer inland migration of the GOM from 1973 to 2010. The methodology developed in this case study effectively connects wetland loss with increased flood defense costs and can be applied to communities with similar challenges.
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Assessing Coastal Road Flood Risk in Arctic Alaska, a Case Study from Hooper Bay
Rising waters and land subsidence are increasing relative sea levels in western and northern Alaska, forcing communities to relocate or armor in place. To appropriately plan and make equitable decisions, there is a need to forecast the risk of flood exposure in coastal Alaskan communities and to evaluate methods to mitigate that risk. This paper conducts use-inspired science to evaluate the current and future flood exposure of roads in Hooper Bay, Alaska, proposes a unit cost of flood exposure to estimate the cost of flooding, and compares various mitigation efforts including elevating roads and building dikes. Nine historic storms and their associated flood depths were subject to return-period analysis and modeled for several sea level rise scenarios. Based on the simulated road flood exposure (km hours/storm), and the storm-return period, an annual flood exposure (km hours/year) was computed. Then, the unit cost of flood exposure (USD/km hours) was determined as the ratio of the cost of flood mitigation (USD/year) to the annual flood exposure mitigated by the project. The analysis found that the unit cost of flood exposure, in conjunction with flood exposure calculations, does provide an approximate flood risk calculation, though a unitized cost of flood exposure needs to be divided into lump sum costs and materials costs. The analysis also found that dikes may be a more cost-effective alternative than road elevation. The flood risk calculation, based on the unit cost of flood exposure, could be made for all of the communities in a given region to identify those communities that face a high flood risk. Furthermore, if one divides the unit cost of flood exposure by the population, one obtains a cost/benefit ratio that potentially could be used to prioritize flood mitigation work.
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- PAR ID:
- 10325992
- Date Published:
- Journal Name:
- Journal of Marine Science and Engineering
- Volume:
- 10
- Issue:
- 3
- ISSN:
- 2077-1312
- Page Range / eLocation ID:
- 406
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/jmse10030406
