Effects of Tropical Storms on Coastal Groundwater Contamination: a Research Agenda

The 2005 hurricane season must be taken as warning of the potential increase in hurricane intensity due to climate change, which has serious implications for the sustainability of coastal communities vulnerable to tropical storms.  These communities must develop physical infrastructure that is resilient to the disastrous consequences of a tropical storm landfall in order to sustainably meet people’s basic needs.  Drinking water systems in particular are vulnerable to hurricane incidence due to the multiplicity of contaminant mixing mechanisms that hurricanes exacerbate in conjunction with the direct storm damage that may take systems offline.  The resultant potable water scarcity necessitates fast response in order to meet public health needs.  Studies following Hurricanes Rita and Katrina in 2005 indicate that boil orders and other institutional response is not sufficient; rapid infrastructural restoration is necessary to ensure access to clean drinking water.

Hurricane-induced water quality degradation of surface water systems has been well documented in many locations, but contamination of groundwater resources has rarely been addressed.  Coastal storm surge, severe winds, and high precipitation drive surface water mixing and contamination with flooding as an additional consequence.  This flooding has the potential to inundate wells, allowing contaminants to enter groundwater resources as is evidenced by saltwater intrusion studies following coastal floods. 

Literature indicates that salinity does quickly return to pre-hurricane levels, but little research has been performed to trace highly concentrated biological contaminant intrusion following a strong tropical storm.  These contaminants could have significantly longer residence  times than salinity, and also have more significant public health effects.  In addition, the surface water contaminant mixing that occurs following a hurricane normally includes significant human waste matter, and many post-hurricane well tests have indicated presence of E.coli and other bacteria.  In flood-prone areas public health threat has typically been addressed by spot treatment of formerly inundated wells with a chlorine dosing, yet some research indicates that the recommended spot treatment is ineffective for restoring water quality in  wells.

Communities historically have not had the capacity to reliably meet their own needs following a hurricane, whether in the or developing countries, and have instead required national and international response efforts to resolve the associated public health problems.  The development of truly place-based water infrastructure within these communities, as has been performed for drought- or flood-prone areas, has the potential for more reliable drinking water delivery in hurricane-prone regions of the world. 

Since groundwater resources are one step removed from the surface water contamination processes, they are more easily protected from contamination and have the potential to serve as an immediate, secure source of drinking water following hurricane incidence.  However, ethical advocacy for groundwater as a better source of water requires that research be performed in three key areas.  Post-hurricane monitoring is necessary to determine the timescale of bacterial contamination in representative groundwater systems.  An effective well requalification procedure must be rigorously developed to meet current hurricane-related drinking water needs.  Finally, improvements must be put in place to prevent contaminant infiltration and protect groundwater resources.