DISCUSSION OF MITIGATION AND ADAPTATION PRACTICES IN RESPONSE TO GROUNDWATER INUNDATION AND THE IMPACTS OF CLIMATE CHANGE AND SEA-LEVEL RISE.

Ashley Holland

East Carolina University GEOL 3500

Background

As human activity continues to influence climate change and sea-level rise, those living in

coastal regions around the globe will be directly impacted. It has been projected that sea-levels

will rise 0.2 m to greater than 1 m in the next 100 years (Manda, 2015). An estimated 200

million people are vulnerable to flooding during temporary sea-level extremes (Rotzoll, 2012).

Furthermore, with sixty percent of the world’s population living within 150 km of the coastline,

this will be a significant problem (Nicholls, 1995). Ten percent of those coastlines comprise what

is known as Barrier Islands, which are the product of sea-level rise over the course of thousands

of years (Masterson, 2014). As a result, their form changes in response to wind, wave, and sea-

level fluctuations. While the impact of climate change and an increase in sea-level will be great,

a less apparent consequence of these events are marine and groundwater inundation. Marine

inundation occurs when sea-levels rise enough to occupy land that was previously dry (Figure

1). A significant increase in sea-levels will simultaneously raise the groundwater table to the

land surface, causing groundwater inundation and flooding (Figure 1).

Figure 1. Conceptual diagram depicting marine and groundwater inundation (Rotzoll, 2012).

Impact Assessment on Bogue Banks Groundwater Resources

For the 3,700 permanent residents and thousands of seasonal residents living on Bogue Banks,

a barrier island, a set of norms are relied on to carry out daily life (www.census.gov). However,

the negative effects of climate change and sea-level rise on groundwater inundation will cause

water management problems and threaten the infrastructure (Manda, 2015). One of the more

evident results of these changes, will be an increase in flooding. As stated before, barrier

islands change shape when major influences such as waves and tides hit the shores

(Masterson, 2014). So, for the residents who own property along the shoreline this can be a

significant problem, if the shoreline recedes into their property. Roads, buildings, and other

infrastructure will also could also compromised in this situation, impacting the daily life of Bogue

Banks residents (Rotzoll, 2012).

What might be more detrimental, in terms of flooding, will be when it coincides with rainfall

events because it raises the groundwater table. This will mean that existing drainage systems

will need to be fixed because they will no longer be able to efficiently drain storm water runoff

(Rotzoll, 2012). An elevated groundwater table can then lead to a salinization of the aquifers,

and a degradation of drinking water (Rotzoll, 2012). Additionally, water and sewer pipes will

corrode and infiltration and drainage will become more difficult due to groundwater inundation

(Rotzoll, 2012). It is for these reasons that adaptation and mitigation procedures must be

developed, as the process of implementation will be costly, time consuming, and dependent on

an educated population.

Discussion of Mitigation and Adaptation Procedures

The extent of the impact that groundwater inundation and its effects will have on Bogue Banks

will depend on how the practices they adopt now to mitigate and adapt to the imminent

changes. While many of these mitigation and adaptation steps will occur simultaneously, one of

the first priorities will be to prevent future developments from building in areas that have been

identified as groundwater inundation zones, as they could be subject to flooding and other

issues as the groundwater table elevates. To accomplish this, the local government will need to

be heavily involved in planning and regulating zones (IPCC, 2014). An investment from the local

government can prove to be invaluable, especially when the Bogue Banks community gets

involved (IPCC, 2014). Offering a series of information sessions to educate the citizens of

Bogue Banks, the stakeholders, will allow them to understand groundwater inundation and the

impact it will have on their home. Similarly, the local government will have the opportunity to

disseminate information about the implementation of mitigation strategies, and any adaptation

programs that stakeholders can take advantage of.

While it is the prerogative for a government entity to claim imminent domain to the areas

identified to be within the hazardous groundwater inundation zone, this will not go over well with

the citizens. For this reason, other options must be considered such as financial incentives

including taxes and subsidies (IPCC, 2014). Understanding that some people may not want to

relocate, even after learning of the potential dangers of the rising sea-levels and groundwater

table, is important. However, the primary goal is to reduce the number of people living near the

groundwater inundation zones. For homeowners, the government can offer to pay half of the

market price of homes in addition to a tax break on property taxes, if the homeowner purchases

a house in neighborhoods that previously had low attrition. By doing this, the government will

still be allowed to collect other taxes associated with homeownership. To further incentivize

homeowners, the money for this opportunity will be put in a guaranteed trust, so it can only be

used in alignment with the terms associated with this deal (IPCC, 2014). All of this will be

funded through an increase in taxes, for every citizen in North Carolina. As a trade-off, the

beaches will be open to the public to allow for revenue from visitors. Some homeowners and

business owners may not want to accept this deal, so another option for them will be to adapt to

the changes. To cope with the inevitable flooding, they can create a semi-permanent structure

by raising their property by way of using ‘stilts’ (Figure 2) (IPCC, 2014). This will mean that the

drainage system will also need to be changed to adapt to the new elevation. While the

government could offer a grant to help accommodate those who fall in this category, this will

depend entirely on how much revenue Bogue Banks can afford to spare.

Figure 2. Adaptation strategy using stilts and other materials to raise the house above the increased water level. (IPCC, 2014).

Perhaps a more unusual solution to address the impact of climate change and sea-level rise,

and its influence on groundwater and marine inundation will be to build an artificial island.

Building an artificial island off of the coast of Bogue Banks will take many years to complete,

because it will involve (for this situation) collection of dirt, sand, and other materials from

development projects throughout North Carolina, and other states if they choose to be involved.

This island will essentially take all of the impact that Bogue Banks would experience, and if built

close enough to Bogue Banks it could become a source of attraction and revenue since it will

not be inhabited.

Conclusion

Groundwater inundation is imminent as a result of climate change and rising sea levels. The

only course of action to protect public safety and reduce damage to infrastructure is to

implement mitigation and adaptation procedures while time is available. Incorporating improved

government practices with public education and investment will greatly reduce the impact from

climate change, sea-level rise, and groundwater inundation.

Works Cited

Intergovernmental Panel on Climate Change. Climate Change 2014: Impacts, Adaptation, and

Vulnerability

Manda, A. K., Sisco, M. S., Mallinson, D. J., & Griffin, M. T., 2015. Relative role and extent of marine and groundwater inundation on a dune-dominated barrier island under sea-level rise scenarios: Marine And Groundwater Inundation Under Sea-Level Rise. Hydrological Processes, 29(8), 1894-1904.

Masterson, J.P., Fienen, M.N., Thieler, E., Gesch, D.B., Gutierrez, B.T., Plant, N.G., 2014. Effects of sea-level rise on barrier island groundwater system dynamics - ecohydrological implications. Ecohydrology, vol. 7, No. 3, pp. 1064-1071.

Nicholls, R. J. 1995 Coastal megacities and climate change. Geo J. 37, 369-379.

Rotzoll, K., Fletcher, C.H., 2013 Assessment of groundwater inundation as a consequence of sea-level rise, Nature Climate, v 3, 477-481.

United States Census (www.census.gov)