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A project I am currently involved with looks at the impacts of climate change on public health in southeast Florida.  The initial grant focused on looking at socially vulnerable populations and the impact on chronic diseases these groups from climate change.  The question was whether climate change, which in southeast Florida is basically sea level rise, would have an impact on health issues.  On the face of it, the correlation between chronic health conditions and climate seems tenuous although the statistics support the link between chronic health impacts and socially vulnerable populations.  But what is interesting is that in general, the climate vulnerable topography and the socially vulnerable people do not correlate.  This may be a southeast Florida issue, but it is the less socially vulnerable who live in the climate vulnerable topography.

Those familiar with the history of southeast Florida know that makes sense because of the beaches.  The beaches are topographically vulnerable but eh wealthy want to live there anyway. But the problem is more pervasive.  The data actually can be mined further to reveal that the older homes (1940s-1960s), generally smaller and of lower value, were traditionally built on the high ground.  Turns out our ancestors were a little smarter than we thought – they actually thought this out.  Aside from Henry Flagler building the railroad on the high ground, most of the cities were located similarly – on the coastal ridge.  Drainage of the Everglades permitted the western migration of residences – newer and larger, but at lower elevation and mostly reliant on drainage across the ridge to the ocean via canals.  But as sea level rises, the water moves more slowly.

The question that must be asked then is what happens as this housing stock ages?  We already see some newer communities, primarily built for retirees, moving to relieve themselves of the 55+ designations to allow the housing stock to be sold – the children of the retirees don’t want the property and desire to sell it – often quickly.  To increase speed of sales (and ultimately retaining some value), eliminating the 55+ opens younger families to move in.  However the lower value of the properties makes them conducive to migration of people who are social vulnerability, so migration may be toward social vulnerable people moving to topographically challenged property.  That portends poorly for the link between climate and health in the future.

Two issues arise from the research.  First future health vulnerability from climate may be more related to vectors and waterborne disease than chronic health effects.  That expands the health vulnerability to all populations.  The second issue is that storm water, sewer roadway and water infrastructure may relieve some pressure on these topographically vulnerable properties, but the people who are moving to then will have significantly less ability to pay for those improvements, creating a political conundrum that will that a significant amount  of leadership to overcome.  That means that resiliency must be built into infrastructure and redevelopment projects now, to address future conditions.  Building in resiliency is not currently being considered by local planners and engineers because the situation is not well understood and a 50 year planning horizon is not the norm.  Also, it would likely create a firestorm of fuss from developers who would pay the costs, which discourages good planning.

Finally, if things accelerate, wealthier parties may begin to see a retreat from vulnerable eastern beaches to higher ground as being a reasonable concept.  However the high ground is currently occupied by socially vulnerable people, creating a potential area of conflict over the fate of displaced residents who’s social status may force them toward the vacant, topographically vulnerable properties.  This is a future problem for planners, developers and officials approving new development with an eye to displacement a concept not in the current thought process.  Thinking about vulnerability means a lot of infrastructure must not only be constructed, but maintained meaning local public works and utility budgets will need to increase in kind.  That means higher rates and charges to populations that may have limits to their ability to pay   Stay tuned…..


In the last blog we discussed 10 planning steps for sea level rises.  When planning 50-100 years other factors can come into play as well.  As a result, to allow flexibility in the analysis due to the range of increases within the different time periods, an approach that uses incremental increases of 1, 2, and 3 feet of SLR is suggested.  Hence infrastructure is built to meet milestones, not arbitrary dates lessening the potential for stranded assets.. The increments can work as threshold values in planning considerations in terms of allowing planners the ability to know ahead of time where the next set of vulnerable areas will be to allow a for proactive response approach that can be matched to the observed future sea levels.

But prior to developing infrastructure plans, the local community needs to define an acceptable level of service (LOS) for the community. A level service would indicate how often it is acceptable for flooding to occur in a community on an annual basis.  1% is 4 days per years and for a place like Miami Beach, this is nearly 2 ft NAVD88, well above the mean high tide.  The failure to establish an acceptable LOS is often the cause of failure or loss of confidence in a plan at a later point in time.  The effects of SLR of the level of service should be used to update the mapping to demonstrate how the level of service changes, so that a long-term LOS can be defined and used for near-term planning.

With the LOS known, the vulnerability assessment is developed using a GIS based map of topography and the groundwater levels associated with wet and dry season water levels.  LiDAR is a useful tool that may be available at very high resolution in coastal areas.  Topographic maps must be “ground-truthed” by tying it to local benchmarks and transportation plans.  USGS groundwater and NOAA tidal data from local monitoring stations to correlate with the groundwater information. Based on the results of these efforts, the GIS-based mapping will provide areas of likely flooding.

GIS map should be updated with layers of information for water mains, sewer mains, canals, catch basins, weirs and stormwater facilities.  Updating with critical infrastructure will provide a view of vulnerability of critical infrastructure that will be funded by the public sector. Ultimately policy makers will need more information to prioritize the needed improvements.  For example, a major goal may be to reduce Economic Vulnerability.  This means identifying where economic activity occurs and potential jobs.  At-risk populations, valuable property (tax base) and emergency response may be drivers, which means data from other sources should be added.

The next step is to analyze vulnerability spatially, by overlaying development priorities with expected climate change on GIS maps to identify hotspots where adaptation activities should be focused. This effort includes identification of the critical data gaps which, when filled, will enable more precise identification of at risk infrastructure and predictions of impacts on physical infrastructure and on communities. The final deliverable will include descriptions of the recommended concepts including schematics, cost estimates, and implementation plan.

So why go through all this.  Let’s go back to the beginning.  It has to do with community confidence in its leaders.  Resident look at whether their property will be protected.  Businesses look at long-term viability when making decisions about relocating enterprises.  The insurance industry, which has traditionally been focused on a one year vision of risk, is beginning to discuss long-term risks and not insuring property rebuild is risk-prone areas.  That will affect how bankers look at lending practices, which likely will decrease property values.  Hence it is in the community’s interests to develop a planning framework to adapt to sea level rise and protect vulnerable infrastructure through a long-term plan.  Plan or….


If you live on an island, and your groundwater table is tidal, what should your datum be for storm water planning purposes?  Average tide?  High tide?  Seasonal high tide?  If you are the local official with this problem, what do you do, realizing that the difference from mean tide and seasonal high tide (when most flooding occurs) is 1.5 feet?  Realizing that property and infrastructure is at much higher risk for periodic inundation, does the failure to address the problem indicate a lack of willingness, understanding, hope or leadership?  We see all four responses among local officials, but the “head in the sand” mode is the most curious.  It’s tough challenges that often define leaders.  With sea level rise, there is time to plan, construct infrastructure in stages, arrange funding, and lengthen the life of infrastructure and property.  Meanwhile, those insurers, banks and the public we talked about in a prior blog wait and watch.

One of the major issues involved with climate changes is sea level rise. Florida has experienced 9 inches of sea level rise since 1900. Projections are 2-3 feet by 2100, perhaps more. Modeling done by my students and I at FAU has demonstrated that in low lying areas, sea level rise will also impact groundwater levels, and accelerate inland flooding. The graphs above compare the traditional bathtub model used by most investigators and our adjusted for groundwater level model. You wee added inland areas of flooding which complicated storm water flooding issues much faster than sea level rise might indicate.

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