Sustainability of US coastal development

Adam D. Griffith, UNC Charlotte (Charlotte, NC): Sustainability of US coastal development

Global rates of sea-level rise (SLR) have accelerated since 1900 (IPCC, 2013) posing a threat to the 3.7 million residents living within 1 mile of high tide in the USA (Strauss et al., 2012). Americans love living near the coast: over half of the US population lives in coastal watershed counties (NOAA, 2013). Between 1970 and 2010, coastal watershed counties increased their population density by 99 people per square mile while inland areas only increased by 23 people per square mile over the same time period (NOAA, 2013). US beaches, therefore, confront pressures from two fronts: erosion from SLR on the ocean side and urban development on the landward side resulting in a phenomenon called “coastal squeeze” (Cooper and McKenna, 2008).

Policy experts typically place SLR responses into one of three categories: (1) protection (shoreline armoring and beach nourishment), (2) adaptation (elevating houses, roadways, and infrastructure in their current place), and (3) retreat (physically moving coastal homes and infrastructure to locations further inland) (Kousky, 2014). Absent a dramatic and highly unlikely reversal of SLR, policy makers in coastal counties and states will continue to confront dilemmas related to the safety of their population and the value of land-based economic resources. Addressing such dilemmas will demand approaches informed by high quality and well-integrated research. This paper synthesizes the diverse scholarship related to these different responses to SLR and outlines a research agenda for future coastal land management research.

Beach nourishment and shoreline armoring have been the de facto policy of US states and towns for decades and now some 225 beaches on the East and Gulf Coasts rely on beach nourishments (Pilkey and Pilkey, 2007). This practice goes against principles of sustainability outlined by Beatley (1995) as maximizing equality, acknowledging ecological limits, and acknowledging environmental costs. Even more Byzantine are the complicated economics that mire decision-making processes at the local, state, and federal levels, which undermine the long-term sustainability of US coasts.

US beach nourishment projects are approved if they demonstrate a favorable cost-benefit ratio, but the results of alteration of the spatial scale of analysis suffer from the modifiable areal unit problem (Openshaw, 1983). If the benefit is assumed over longer periods of time or over larger geographic areas, then the value will be larger favoring protection and adaptation. According to Jennifer Armstrong of the Army Corps of Engineers (ACOE), the 50 beach nourishments of Virginia Beach have prevented $443 M in damage (Ludden, 2013). This math relies on economic models and assessed values of homes and properties. The problem in using assessed values for economic justification of coastal engineering projects is that public tax dollars are used to protect private property. If a $1 M private home were built in the 100-year flood plain, the logic of the ACOE would allow $999,999 of tax expenditures on protection measures and still defend the economic basis of the project. The value of the home to tax payers is the ad valorem tax value. Coburn (2011) finds that the average ad valorem benefit in NC coastal counties for a $1 M home is only 0.6% of the assessed value or $6,014. When ad valorem tax values are used instead of assessed values, the $443 M figure is significantly lower; perhaps only $44 M if a liberal 0.1% is applied. This math is pervasive in the economic justifications of engineered beaches (e.g. Fletcher et al (2013), Holleymann et al. (2007), Edwards and Gable (1991)). This math promotes protection and adaptation, which may be tenable over short timescales, but become unsustainable over longer periods of time.

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Edwards, S. F., & Gable, F. J. (1991). Estimating the value of beach recreation from property values: an exploration with comparisons to nourishment costs. Ocean and Shoreline Management, 15(1), 37-55.
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The current state of the coast in the United States truly fits the criteria of a wicked problem (Rittel and Webber, 1973). There is no clear answer and no definitive solution. Compounding the issues are the motives of the individual agents acting on their own accord – the homeowner prepared to defend what is theirs, the municipality prepared to defend their tax base, and the state to ask the federal government to pay for most of it. Most discouraging are recent plans states and towns have to develop most of the land below 1 m in elevation. Titus et al. (2009) reviewed the land use planning documents of 131 coastal jurisdictions between Massachusetts and Florida and evaluated undeveloped land as “most likely, likely, unlikely, or least likely to be protected as sea level rises.” Of the land below 1 m, 60% of it is likely to be developed and only 9% preserved to allow migration of wetlands inland. The results of this continued business-as-usual scenario will require extensive additional sea-level rise protection measures with which our country only has extensive experience in New Orleans, LA. If the research of Titus et al. (2009) is accurate, this also will require a substantial investment in infrastructure near future sea-level over the entire US east coast. At best, this is unsustainable. At worst, it is irresponsible, profit-minded, and myopic. Titus et al. (2009) also point out that if the cumulative effects of sea walls violate the Clean Water Act, then the actions could also be illegal.

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