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Climate Change Vulnerability
Assessment and Adaptation Plan
TECHNI CAL M E M O
EŽǀĞŵďĞƌ 2016
City of Sarasota
Climate Change Vulnerability
Assessment and Adaptation Plan
Step 1
Technical Memorandum
Sarasota, Florida
November 2016
Contents
Executive Summary .................................................................................................................................................. ES-1
1
Introduction ........................................................................................................................................................ 1
2
Regional Landscape and Geology........................................................................................................................ 3
3
Climate Trends – An Overview ............................................................................................................................ 4
3.1
3.2
3.3
4
3.1.1
Observational Sea Level Rise - Global ........................................................................................ 6
3.1.2
Observational Sea Level Rise – Local and Regional ................................................................... 7
Temperature ............................................................................................................................................ 9
3.2.1
Observational Temperature Change – Global ........................................................................... 9
3.2.2
Observational Temperature Change – Local and Regional ........................................................ 9
3.2.3
Observational Changes in Urban Heat Islands ......................................................................... 10
Precipitation and Extreme Storms ......................................................................................................... 11
3.3.1
Observational Changes in Precipitation and Storm Intensities ............................................... 12
3.3.2
Observational Changes in Extreme Storm Events.................................................................... 13
Vulnerability Assessment Overview .................................................................................................................. 14
4.1
5
Sea Level Rise and Storm Surge ............................................................................................................... 5
Climate Projections and Vulnerability Assessment Tools ...................................................................... 14
4.1.1
Sea Level Rise ........................................................................................................................... 15
4.1.2
Storm Surge ............................................................................................................................. 16
4.1.3
Temperature ............................................................................................................................ 17
4.1.4
Precipitation and Extreme Storms ........................................................................................... 18
Assessment of Vulnerable Infrastructure ......................................................................................................... 20
5.1
Water Supply.......................................................................................................................................... 21
5.2
Wastewater and Reclaimed Water ........................................................................................................ 21
5.3
Stormwater ............................................................................................................................................ 22
5.4
Transportation ....................................................................................................................................... 23
5.5
Coastal Protection .................................................................................................................................. 24
6
Summary and Next Steps .................................................................................................................................. 24
7
References ........................................................................................................................................................ 26
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Figures
Figure 1: Reconstruction from Ice Cores (from Proxy Measurements) ......................................................................... 1
Figure 2: Location Map .................................................................................................................................................. 4
Figure 3: Global Distribution of CO2 Concentration in ppm from 1000-2000 A.D. ........................................................ 5
Figure 4: Post-Glacial SLR Changes during the last 24,000 years of the Earth’s History................................................ 6
Figure 5: Global Average Absolute Sea Level during the POR 1870-2008 ..................................................................... 7
Figure 6: Monthly Mean Sea Level Trend for Fort Myers, FL Tide Gauge - 1900 to present ......................................... 8
Figure 7: Monthly Mean Sea Level Trend for St. Petersburg, FL Tide Gauge - 1900 to present .................................... 8
Figure 8: Global Temperature Change (1880 to 2000) ................................................................................................. 9
Figure 9: Average Annual Temperature for POR 1965-2014 (station 5 miles ESE of Bradenton, FL) .......................... 10
Figure 10: Trend in the number of days (length) in the Hot Season in Florida ........................................................... 11
Figure 11: Percentage of Extreme 1-day (24-hour) Rainfall Events Annually in the Contiguous U.S. ........................ 12
Figure 12: Percentage of Extreme 1-day (24-hour) Rainfall Events Annually in the SE U.S. ....................................... 13
Figure 13: Yearly Dollar-cost of Specific Disasters from 1980 to 2016 ....................................................................... 14
Figure 14: NOAA Relative Sea Level Change (rise) Projection (2050) ......................................................................... 16
Figure 15: Inter-connectivity and Complexity of Identifying and Quantifying the Impact of Air Temperature
Increases/Extremes on a Community ........................................................................................................ 18
Figure 16: City of Sarasota Baysheds ........................................................................................................................... 24
Figure 17: Summary of Global and Regional Climate Scenarios .................................................................................. 24
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Executive Summary
The climate has changed, is changing now, and will continue to change into the future. The rate of change is
influenced by both natural processes and human activities. Understanding a community’s vulnerabilities to climate
change is essential for reducing exposures to risk and informing decisions to adapt. A community’s resilience to
climate change begins with the discovery and assessment of infrastructure vulnerabilities to natural and man-made
hazards. Adapting to climate change, particularly with regard to public health, safety and infrastructure services for
coastal communities, like the City of Sarasota, will become an increasingly important focus during the 21st Century.
As a modern coastal community with miles of tidally-influenced shorelines, the City has the essential responsibility to
protect public health and safety by ensuring resiliency of municipal infrastructure. The purpose of the City of
Sarasota Climate Change Vulnerability Assessment and Adaptation Plan is to conduct a comprehensive assessment of
critical infrastructure to identify system vulnerabilities to future climate change and inform decisions to adapt
strategies for near- and long-term threats associated with those changes.
Global climate modeling has shown that changes have already occurred with regard to sea level rise (SLR), extreme
temperature, and precipitation intensity and that these changes are expected to be exacerbated over time, which will
lead to greater impacts to the City. Global Climate Models to project future infrastructure vulnerabilities are valuable
tools that are being perfected as new methodologies are applied to greater computing power. We will use the most
recent and relevant climate modeling and assessment tools to better understand how each of four defined climate
variables (i.e. SLR, storm surge, extreme heat, and extreme precipitation) might impact the City of Sarasota. The City
recognizes the implications of climate change and the potential impact to public assets, including transportation, water
supply, waste water, and stormwater management systems, as well as overall coastal resiliency.
Globally, sea level increased about eight inches during the 20th century. SLR has already changed Florida’s coastal
biogeography and has presented new challenges for protecting public infrastructure and coastlines around the state.
The current SLR baseline for the Sarasota region, which represents observable, present-day conditions occurring
without regard to any change in the SLR trend, suggests an increase of 3.6 to 3.8 inches by 2050 and 8.8 to 9.4 inches
by 2100 (assuming no acceleration or deceleration). However, climate forecasts suggest SLR acceleration will occur in
this area, which will further challenge coastal resiliency and public infrastructure, as well as stress City shorelines and
Sarasota Bay.
Sea level rise combines with other climate stressors such as storm surge, temperature and extreme precipitation to
exacerbate threats to coastal infrastructure. Storm surge associated with extreme storms and seasonally high tides
poses an immediate and credible threat to our community as surges extend increasingly higher and further inland.
Atmospheric CO2 concentrations have increased from around 280 parts per million (ppm) to over 400 ppm over past
150 years, which have generally correlated to increases in temperature. Global average sea surface temperatures
(SST) are on average 2.6⁰F warmer and are expected to continue to rise with warming air temperatures. By 2050, the
Gulf of Mexico SST is expected to be at the least 1.3⁰F warmer, but could be as much as 4⁰F or 5⁰F warmer. Air
temperatures, particularly at night, are increasing around the globe and average annual temperatures have increased
in the Sarasota region over the past 50 years by 2.2⁰F. Notably, a warmer atmosphere holds and releases more
moisture than a colder one, which is why rainfall intensities have and will continue to increase as the atmosphere
warms. Extreme precipitation events, including changing weather patterns, will challenge management of municipal
water systems as well.
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ES-1
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1
Introduction
Understanding a community’s vulnerabilities to climate change is essential for informing decisions to adapt and
reducing exposure to risk. A community should develop effective adaptation strategies based on locally-informed
perspectives in order to embrace opportunities and confront risks associated with climate change. The target goal is
for a municipality to provide continuity of public service and safety during periods of infrastructure stress and system
shock. A community that provides infrastructure with a certainty of ability and protection for public services and
safety will give it a competitive advantage across economic, human and natural environments as climate change has a
progressively greater impact on the region.
According to the National Climate Assessment, Southeastern U.S. study, this region is, and will continue to be,
particularly susceptible to sea level rise, extreme heat, extreme precipitation, and decreased water availability.
Municipalities around Florida are experiencing the effects of climate change as subtle changes in sea level, storm
surge, heat, and precipitation patterns are producing far reaching impacts and consequences in coastal communities.
Sea level rise (SLR) is already causing changes to Florida’s coastal biogeographic regions and presenting challenges
with protecting public infrastructure and coastlines around the state. The problems experienced in many coastal
cities during seasonally-high tides (i.e. King Tides) are a testament to this issue. As a Gulf Coast community, the City
of Sarasota recognizes the implications of climate change and is acutely aware of how SLR, storm surge, extreme heat,
and extreme precipitation can impact public assets, including transportation, water supply, waste water, and
stormwater management systems, as well as coastal resiliency and public safety. In 2007, the City pledged to
minimize its impact on climate change by signing the U.S. Mayor’s Climate Protection Agreement.
The climate has changed throughout time, is changing now, and will continue to change into the future. Climate is
defined as long-term averages and variations in weather measured over a period of several decades (at least 30-years
of period of record), which includes observations of land, atmosphere, ocean and ice. The rate of change is
influenced by both natural process and human activities, such as increases in atmospheric CO2 (Figure 1). How a
community responds and adapts to climate change is critical to public well-being. Local adaptions to climate change,
particularly in coastal communities like the City of Sarasota, will be increasingly important during the 21st Century.
Figure 1: Reconstruction from Ice Cores (from Proxy Measurements)
Source: NOAA http://climate.nasa.gov/vital-signs/carbon-dioxide/
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Climate forecasts for sea-level change suggest SLR acceleration in our area, which will further challenge coastal
resiliency and management of public infrastructure, as well as stress natural shorelines and Sarasota Bay. Storm surge
associated with extreme storms and seasonally-high “King Tides” poses an immediate and credible threat to our
community as tides surge increasingly higher and extend further inland. Modern infrastructure in coastal
communities such as the City of Sarasota has not typically been designed to accommodate SLR and storm surge and
now considerations regarding vulnerability, replacement or armament must be addressed. Extreme heat also
threatens our region. Average annual air temperatures have increased in the Sarasota region over the past 50 years,
which not only impacts, but also threatens human health. Protection of our regional water supply must also be
considered to better understand the threats posed by saltwater intrusion, which will be exacerbated by sea-level rise,
as well as variability in precipitation. Extreme precipitation events, including changing weather patterns, will also
challenge management of water treatment systems.
2012 King Tide at Bayou Louise at Siesta Key (June 2012)
Photos by Larry Stults
Community resilience to climate change begins with the discovery and assessment of vulnerabilities to natural and
man-made hazards. As a modern coastal community with miles of tidally-influenced shorelines, the City has an
essential responsibility to protect public health and safety by ensuring resiliency of municipal infrastructure. A Six
Step Systematic Process was recommended by the City to evaluate infrastructure vulnerabilities and develop climate
adaption strategies including:
1.
2.
3.
4.
5.
6.
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Research, Analyze, and Present Relevant Climate Issues
Inventory Infrastructure & Identify At-Risk Municipal Systems
Conduct a Vulnerability Assessment of Affected Systems
Prioritize Vulnerabilities
Develop Adaptation Strategies to Reduce Vulnerability
Create and Present the Adaptation Plan
2
2
Regional Landscape and Geology
Florida is 500 miles long and 160 miles wide and is comprised predominantly of low lying plains with the exception of
low hills around 200-300 feet above sea level in central and northern Florida. It is divided into four geographical
landforms including the Atlantic Coastal Plain, the south Atlantic Coastal Plan, the East Gulf Coastal Plain, and the
Florida Uplands. The City of Sarasota lies within the East Gulf Coastal Plain and is geographically defined by low
elevations and flat rolling topography with small tidal creeks and barrier islands.
Florida has over 1,200 miles of coastline of which 770 miles are along the Gulf of Mexico. Florida’s intricate tidal
shoreline, which includes inlets, bays, tidal creeks, and rivers, is significantly longer at 5,095 miles (NOAA Office for
Coastal Management). Many of these shorelines are at risk due to climate-related change including ecosystems such
as beaches, bays, estuaries, salt marshes, mangroves, bayous, shellfish bars, seagrasses, and reefs, all of which
provide various ecological and economic benefits in terms fisheries, local products, recreation, and aesthetics.
Most of Florida’s approximately 20 million residents live within 60 miles of a coast and three-fourths of Florida’s
population resides in a coastal county, which provides built environments and modern infrastructure services (FOCC,
2010). Some estimates suggest about 40-inch rise in sea level by 2100, which means impacts will occur to
approximately nine percent of Florida’s land area (more than 4,700 square miles) and impact 1/10 of the state’s
population (FOCC, 2010). Estimates presented in the 2010 report by the Florida Oceans and Coastal Council (FOCC)
suggest an infrastructure replacement value from this level of impact of $2.0 trillion, which is estimated to increase to
$3.0 trillion by 2030 due in part to increases in property value.
The City of Sarasota is a coastally-dependent city located along the Gulf of Mexico in Sarasota County (Figure 2).
Typical temperatures range from an average of around 72°F during the winter months to about 90°F in the summer.
An average of 53.6 inches of rain falls each year with the majority falling during the summer months. This westcentral coastal City includes Sarasota Bay and the barrier islands of Lido Key and a portion of Siesta Key. The City
mainland sits 16 feet above sea level while the barrier islands average around 3 feet above sea level, making threats
of storm surge and moderate sea level rise an important consideration. Increases in sea level in combination with
extreme storms threaten the City’s barrier islands with erosion and over wash deposition. The City encompasses
nearly 24 square miles including approximately 10 square miles of water (City of Sarasota FMP 2015-2020).
Approximately 40 miles of coastline surround the City, including 32 miles of man-made structures and eight miles of
natural land (City of Sarasota FMP 2015-2020).
Public services and critical infrastructure managed
and maintained by the City of Sarasota are at
increased risk due to climate-related changes such as
rising sea levels, storm surge, extreme heat and
flooding from extreme precipitation. The City includes
more than 500 miles of roads (many near the coast),
water treatment and wastewater facilities less that 1mile from the coast, stormwater management
systems discharging to the bay and is underlain by
porous aquifers vulnerable to saltwater intrusion.
Public infrastructure assets need to be adapted to
weather the forecasted climate-related changes.
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City of Sarasota – Photo by Visit Sarasota County
3
Figure 2: Location Map
3
Climate Trends – An Overview
The term “climate change” is used to explain variations in global or regional climate over a defined period of time.
Climate changes can be influenced by natural processes such as changes in solar activity or increased particulates in
the atmosphere from forest fires or volcanoes, or human activities such as emission of greenhouse gases including
carbon dioxide (CO2), methane (CH⁴), and nitrous oxides (NOX), which in turn influence other climate changes.
Growing evidence complied from scientists, researchers and engineers around the world support that the climate is
changing and that the primary cause is linked to increasing levels of CO2 in the atmosphere. According to the
Intergovernmental Panel on Climate Change (IPCC), 97% of climate scientists worldwide believe this statement to be
true. It is becoming increasingly difficult to dispute evidence that the climate is warming. Atmospheric CO2
concentrations have increased from around 280 parts per million (ppm) to over 400 ppm over past 150 years, which
have generally correlated to increases in temperature (http://climatecenter.fsu.edu/topics/climate-change). Figure 3
shows the distribution of global atmospheric CO2 for the last 100 years of earth’s history. Data prior to the 20th
century was derived from Greenland ice cores.
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Figure 3: Global Distribution of CO2 Concentration in ppm from 1000-2000 A.D.
Source: Intergovernmental Panel on Climate Change
Global climate change is a reality. Impacts from changes in global climate are occurring on local and regional levels to
a degree that should warrant concern and proactive response. Although future climate projections using Global
Climate Models are important tools for assessing future risk, observational data shows us that the climate has already
changed within the period of record beyond the design criteria used for much of our community’s infrastructure.
The following three sections address these observed global, regional and local trends in climate to serve as a baseline
for projected changes to be described in the context of the vulnerability assessment (Section 4) for this project.
3.1
Sea Level Rise and Storm Surge
Globally, sea level increased by about eight inches during the 20th century (http://www.globalchange.gov/). Changes
in global sea levels are driven by various factors including thermal expansion of ocean water caused by increasing
water temperature, melting polar land ice, glacial rebound, and discharge of aquifer withdrawals. Researchers have
been able to reconstruct sea level and global temperature changes for the past several thousand years using
instrumental records and proxy data from climate archives to develop a better understanding of observed and future
changes (Kemp et al. 2011). This research suggests that current climate warming is unprecedented in the past two
millennia; however, the understanding of sea-level variability and climate deviations during this period is limited
(Kemp et al. 2011). Sea level rise combines with other climate stressors such as storm surge and extreme
precipitation to exacerbate threats and cause damage to coastal infrastructure.
In order to give perspective to future vulnerabilities from
climate-related sea level rise for this assessment, it is necessary
to understand that the sea level has undergone a steady rise
during the available period of record (POR) that should be used
as a baseline for future change. The following two sections will
provide the information necessary to establish this baseline for
the climate change considerations to be made for the
vulnerability assessment as described in Section 4.
Glacier (i.e. land ice) – Canadian Arctic
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3.1.1
Observational Sea Level Rise - Global
An understanding of global sea level rise begins with a historic perspective of how the oceans of the world got to
where they are today. The momumental changes in global sea level that have occurred through the millennia as a
result of changes in global temperatures can be put into context by the analysis provided in Figure 4. At the peak of
the last glacial period (ice-age) roughly 22,000 years ago, global sea levels were about 426 feet (130 meters) lower
than they are today. Since that time, the melting of the glacial ice, glacial rebound, and other factors have
contributed to a dramatic rise in sea level that leveled off to near current levels about 7000 years ago.
Figure 4: Post-Glacial SLR Changes during the last 24,000 years of the Earth’s History
Source:
Open Source Systems, Science, Solutions
Global trends in sea level have continued at a much slower rise during the last 100+ years. Figure 5 shows the rate of
global sea level rise during the POR 1870-2008. This observed trend indicates about a nine inch rise in global sea
levels during an approximate 140 year POR.
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Figure 5: Global Average Absolute Sea Level during the POR 1870-2008
Source: Commonwealth Scientific Industrial Research Organization in collaboration with the University of Colorado, Boulder
3.1.2
Observational Sea Level Rise – Local and Regional
The same factors that have been contributing to sea level rise throughout the millennia are still in play today along
the western coast of Florida. These factors are expected to be complicated and accentuated by climate change with
the biggest change coming as the result melting land ice and thermal ocean expansion. To better understand the
implications of climate change in relation to currently observable trends, we consider the baseline, or historic
reference, which is the state against which change is measured.
For this vulnerability assessment, in order to derive a baseline of potential future changes in sea level rise, it is
necessary to obtain a clear understanding of historic change of sea level in this region. In Figure 6 and Figure 7 we
delineate the current baseline, which represents our observable, present-day conditions, in order to understand
changes that are occurring without regard to any projected acceleration or deceleration in the trend. These figures
show the historic fluctuations and average annual sea level rise at two long-term tide reporting stations (Fort Myers
and St. Petersburg) in the closest proximity to the City of Sarasota along the western coast of Florida from the dates
of recorded measurements at each gauge, which are 1965 and 1947, respectively.
To create the baseline, scientists often use the year 1990 as the “baseline year” since it represents an important point
of reference that industrialized nations measure against to evaluate reductions in GHG emissions (see U.N. Kyoto
Protocol). The year 1990 was the year when the scientists began looking at these data in terms of climate change and
it serves as a dividing line between historic data and future data projections. For the tables and calculations below,
SLR was measured from sea levels observed in 1990 (i.e. set at zero) to give a sea level rise of 2.55 inches, which was
observed in our region in 2015.
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Figure 6: Monthly Mean Sea Level Trend for Fort Myers, FL Tide Gauge - 1900 to present
8725520 Ft. Myers, FL
0.11 +/- 0.019 in/yr
Inches
12
Monthly mean sea level with the average season cycle removed
10
Linear (Linear Mean Sea Level Trend)
8
Linear (Upper 95% Confidence Interval)
6
Linear (Lower 95% Confidence Interval)
4
Baseline year 1990
2
0
-2
-4
-6
-8
-10
-12
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
Year
Figure 7: Monthly Mean Sea Level Trend for St. Petersburg, FL Tide Gauge - 1900 to present
8726520 St. Petersburg, FL
0.105 +/- 0.01 in/yr
10
8
6
4
Inches
2
Monthly mean sea level with the average season cycle removed
Linear (Linear Mean Sea Level Trend)
Linear (Upper 95% Confidence Interval)
Linear (Lower 95% Confidence Interval)
Baseline year 1990
0
-2
-4
-6
-8
-10
-12
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
Year
Analysis of the data presented in Figure 6 and Figure 7 indicates that average annual rise in sea level is on the order of
between 0.10 in/year and 0.11 in/year at the City of Sarasota. A closer look at these data reveals that from 1990 to
present, rise in sea level has been on the order of 0.11 in/year at Ft. Myers and 0.105 in/year at St. Petersburg. We
referenced the two nearest tide gauges as a means to validate the data; however, given the similarities in output
from both gauges, and the fact that the St. Petersburg gauge has 18 more years of measured data, we expect to
reference the St. Petersburg gauge for the City of Sarasota vulnerability assessment. A linear extrapolation of the
mean sea level trend of these historic data for the entire POR reveals that by the year 2050, St. Petersburg will see a
baseline SLR of 3.6 inches and by the year 2100, this historic trend would yield a rise of 8.8 inches.
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3.2
Temperature
Air temperatures, particularly night air temperatures, are already showing an upward trend in many portions of the
globe and are of direct concern and consequence to the City of Sarasota and the State of Florida. As identified above,
observed changes in air temperature over time will be used as a baseline to which climate projections will be applied
so that existing trends will be accounted for throughout the assessment of vulnerability.
3.2.1
Observational Temperature Change – Global
Record-setting heat waves are a result of weather variations and can be tracked back into the last century,
worldwide. However, as global average temperature’s warm overall, heat waves can be expected to increase in
frequency and intensity and cold spells are forecast to become less frequent (EPA - https://www.epa.gov/climateindicators/climate-change-indicators-high-and-low-temperatures). In order to obtain a better understanding of this
phenomenon, a review of these changes on a global scale can be seen in Figure 8, which shows the changes in mean
global temperatures since the late 1800s.
Figure 8. Global Temperature Change (1880 to 2000)
Source: NOAA: U.S. National Climatic Data Center, 2001
3.2.2
Observational Temperature Change – Local and Regional
Average annual temperatures have increased in the Sarasota region over the past 50 years by 2.2⁰F as observed at
the meteorological reporting station located 5 miles ESE of Bradenton, FL. Figure 9 provides a look at average annual
temperature changes for the POR 1965-2014 for this meteorological reporting station as compiled by the Office of the
Florida State Climatologist. The trendline (green line) on Figure 9 shows this temperature increase during the POR.
These findings indicate that the changes in air temperature over the last 50 years within the vicinity of the City of
Sarasota are almost exactly on par with the global temperatures changes observed by NASA.
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Temperature (F°)
Figure 9: Average Annual Temperature for POR 1965-2014 (station 5 miles ESE of Bradenton, FL)
Source: Florida Climate Center – Office of the State Climatologist
Trendline in green (↑ 2.2°F)
3.2.3
Observational Changes in Urban Heat Islands
One of the consequences of urbanization, population growth and the infrastructure that accompanies those
parameters is an increase in impervious surfaces and non-vegetated areas. This increase in pavement for roads, roofs
of houses, and concrete for buildings and other man-made components of civilization is called the Urban Heat Island
(UHI). UHIs happen when heat is trapped, created, discharged and/or reflected from these hardened surfaces
thereby increasing temperatures within a city compared with surrounding rural areas. This “effect” can lead to an
inescapable loop. It has been linked to increased energy consumption (to cool interior buildings), which in turn leads
to increases in CO2 emissions, an increase in air pollutants from greenhouse gas (GHG) emissions such as ozone, and
thermal pollution in water leading to greater evaporation - all of which can further exacerbate climate change.
While there have been no available studies specific to the City of Sarasota, information on the impact of the UHI
effect on the State of Florida can be obtained through analysis of geographic changes in the length of the hot season,
which typically starts around the beginning of May and ends in the middle of November in Sarasota. Figure 10 shows
these changes during the 58-year POR from 1950-2007 in the state. The Gold Coast in south Florida has seen a
tremendous increase in the length of the hot season, which is primarily attributable to the UHI effect; however, much
smaller increases have occurred in areas like Sarasota that have not experienced similar periods of urbanization in the
last 58 years. In fact, the increase in the number of days in the hot season in Sarasota is primarily due to a changing
climate, as per Section 3.2.1.
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Figure 10: Trend in the number of days (length) in the Hot Season in Florida
Source: Florida Climate Center (http://climatecenter.fsu.edu/topics/specials/floridas-hot-season)
3.3
Precipitation and Extreme Storms
As discussed in Section 3.2, the global and local annual air temperatures have been rising over the past decades.
While this rise in air temperatures is of great consequence to the City of Sarasota, an ancillary impact of the increase
in air temperature is its effect on precipitation intensity. A stalwart equation utilized in hydro-meteorology explains
this phenomenon. The Clausius-Clapeyron equation and/or relation tell us that the equilibrium between water and
water vapor depends upon the temperature of the system. If the temperature increases the saturation pressure of
the water vapor increases. In other words, warmer air can hold more moisture than colder air. Thus, a warmer
atmosphere can hold and release more moisture than a colder one. This relation explains why rainfall intensities
have and will continue to increase as the atmosphere warms.
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3.3.1
Observational Changes in Precipitation and Storm Intensities
While global precipitation intensities have been observed to be changing, changes in the U.S. and particularly in the
southeast U.S. have been profound during the last 100 years of POR. Figure 11 shows the increase in the yearly
percentage of 24-hour precipitation extremes that occurred in the U.S. between 1910 and 2015. The binomial trend
line (red line) shows that nearly every year since 1990 has been above the mean percentage with a significant
upward, yet cyclical trend during the period 1990 to 2015. The linear trendline (yellow line) shows the year-over-year
increase in the number of intense rainfall events. Figure 12 provides a look at this same statistic as it applies to the
southeastern U.S. during the POR 1910 to 2015. This pattern of increasing changes in precipitation intensity is
expected to continue well in the next century. The trend identified in Figure 12 will be utilized for the baseline for the
understanding of climate change guidance to be applied for the vulnerability assessment for the City of Sarasota
infrastructure.
Figure 11: Percentage of Extreme 1-day (24-hour) Rainfall Events Annually in the Contiguous U.S.
Source: NOAA National Center for Environmental Information
Linear trendline in yellow
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Figure 12: Percentage of Extreme 1-day (24-hour) Rainfall Events Annually in the SE U.S.
Source: NOAA National Center for Environmental Information
Linear trendline in yellow
3.3.2
Observational Changes in Extreme Storm Events
Figure 13 shows an interesting perspective of the increase in the frequency, intensity and impact of extreme storms
over the years. Severe storms are depicted in green. While this graphic indicates other hazards, the amount of dollarcost damage wrought by extreme storms has jumped exponentially in recent years. This is partially due to a
significant increase in structures begin built in more susceptible locations, but the overall consequence of this analysis
is the fact that there have been a greater number of extreme storm events. The flooding identified in this graphic is a
consequence of extreme storms as well.
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Figure 13: Yearly Dollar-cost of Specific Disasters from 1980 to 2016
Source: NOAA – National Center for Environmental Information
4
Vulnerability Assessment Overview
Global climate modeling has shown, through the use of a variety of future emissions scenarios, that the changes that
have already occurred in air temperature, SLR and precipitation intensity are expected to be exacerbated over time,
which will lead to greater impacts to the City of Sarasota. The purpose of the City of Sarasota Climate Change
Vulnerability Assessment and Adaptation Plan is to conduct a comprehensive assessment of existing infrastructure to
identify anticipated system vulnerabilities to future climate change and to inform decisions to adapt strategies for
near- and long-term threats associated with those changes. We will look at system resiliency, maintenance and
operation, and opportunities and benefits for adaptation to protect existing systems. To facilitate this we will
interview professionals to gather institutional knowledge to understand the City’s regional concerns, needs and goals,
as well as utilize existing climate models, as described below.
4.1
Climate Projections and Vulnerability Assessment Tools
The use of Global Climate Models (GCM) to project future climate variables is slowly being perfected as new
methodologies are applied to greater computing power. In addition, the IPCC developed a standard approach to
modeling climate scenarios, which enables incorporation of multiple factors to predict how future warming will
contribute to climate change. This standard set of scenarios, or Representative Concentration Pathways (RCP), help
ensure that research is complementary and comparable by defining consistent starting conditions, historical data and
projections to be used across the various branches of climate science. The IPCC defines four RCPs (i.e. RCP8.5, RCP6,
RCP4.5 and RCP2.6 - also referred to as RCP3-PD) to describe four possible rates and magnitudes of climate change
depending on how much greenhouse gases are emitted. A short synopsis to better understand RCPs is available here:
http://www.nature.com/nclimate/journal/v1/n1/box/nclimate1058_BX1.html
We anticipate using the following climate change modeling and assessment tools for each of the four defined climate
variables discussed below.
November 2016
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4.1.1
Sea Level Rise
Recommended Assessment Tool(s):
NOAA Digital Coast Sea Level Rise Mapper (https://coast.noaa.gov/digitalcoast/tools/slr)
Increases in sea level will stress the City of Sarasota’s infrastructure. Coastal flooding can be expected to inundate
stormwater systems and salinity can be expected to affect the structural integrity of building materials, increase
infrastructure fatigue and maintenance costs, and decrease the functional life of assets. Shorelines along barrier
islands and Sarasota Bay will retreat and coastal erosion will become increasingly common. High tide events will
undermine seawalls and other hardened shorelines leading to increased risk of structural damage, particularly during
storms and coastal flooding events.
This vulnerability assessment will use NOAA future sea level projections and current climate data specific to the
Sarasota Region and layer the information onto the physical landscape of the City. The NOAA Digital Coast Sea Level
Rise web mapping tool allows the visualization of community-level impacts from coastal flooding or sea level rise (up
to 6 feet above average high tides). Photo simulations of how future flooding might impact local landmarks are also
provided, as well as data related to water depth, connectivity, flood frequency, socio-economic vulnerability, wetland
loss and migration, and mapping confidence. Features that will greatly aid the impact analysis of future sea level rise
for the City of Sarasota include the ability to:
•
Visualize potential impacts from sea level rise through maps and photos
•
Learn about data and methods through documentation
•
Share maps and links via email and social media
•
Download inundation layers and digital elevation models, and access web map services for custom GIS
applications, which will be extremely important to better understand inundation elevations and their
impact on infrastructure in the C
The NOAA Digital Coast Sea Level Rise Mapper allows the user to select a given height for SLR. Our team will utilize a
range of future sea level scenarios developed by NOAA that identify the level of risk associated with the four RCPs
used to model SLR. These RCP represent everything from a world of significant greenhouse gas mitigation (RCP2.6) to
a world with no mitigation and expanding growth (RCP8.5). This analysis is site-specific and downscaled to the closest
tide gauge to the City of Sarasota, which is located at St. Petersburg.
Although utilizing the same data shown in Figure 7 above, Figure 14 depicts SLR for our region relative to conditions
in 2015 (as opposed to the 1990 baseline year). Figure 14 depicts SLR projections for NOAA Low (RCP2.6), NOAA
Intermediate Low (RCP4.5), NOAA Intermediate High (RCP6.0), and NOAA High (RCP8.5) out to the year 2100. As
discussed in Section 3.1.2, NOAA Low represents our baseline, which extends the historical rate of change without
considering the already observable acceleration of this rate. The NOAA Intermediate Low and NOAA Intermediate
High incorporate ocean warming without ice sheet loss and with some ice sheet loss, respectively, the latter of which
scientists have actually been observing. NOAA High represents ocean warming with a maximum loss of ice sheets,
which some scientists believe may be possible by end of the century.
November 2016
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Figure 14: NOAA Relative Sea Level Change (rise) Projections (2100)
Gauge: 8726520, St. Petersburg, FL
7.00
RSLC in feet (LMSL)
6.00
NOAA Low (Historic)
NOAA Int Low
NOAA Int High
NOAA High
5.00
Paris
Agreement
Target
4.00
3.00
2.00
1.00
0.00
2015
Baseline
2025
2035
2045
2055 2065
Year
2075
2085
2095
Source: NOAA tide gauge 8726520, St. Petersburg, FL
Paris Agreement (2015): Global action agreement to avoid dangerous climate change by limiting global warming to well below 2°C.
4.1.2
Storm Surge
Recommended Assessment Tool:
NOAA’s Coastal Flood Exposure Mapper (https://coast.noaa.gov/digitalcoast/tools/flood-exposure)
Storm surge poses an immediate and credible threat to the City of Sarasota and surges are expected to worsen in
terms of frequency and intensity as sea levels rise. Vulnerability to storm surge will increase in our region as surges
associated with extreme storms (e.g. tropical storms and hurricanes), astronomical tides, wind, and waves become
more frequent. Factors affecting storm surge include the direction of the storm approach, the speed of the storm
approach, the point of landfall, and the storm intensity (Weisberg, et al. 2006).
For a complete understanding of the coastal flood risk for the City, wave conditions must be estimated concurrent
with storm tides. NOAA’s Coastal Flood Exposure Mapper (CFEM) tool, which is very similar in configuration and
application to the sea level rise tool, is a visualization tool for assessing coastal hazard risks and vulnerabilities for
communities. The interface can be customized with user-defined maps that show the people, places, and natural
resources exposed to coastal flooding. The maps can be saved, downloaded, or shared to communicate flood
exposure and potential impacts. This tool allows the user to define the scale of the event so that future storm surge
and coastal flooding scenarios can be rendered within the tool’s framework and projected on the City to define
impacts and develop “What if?” scenarios that represent future climatic events.
November 2016
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Although future increases in the magnitude of storm surges are expected to be a consequence of increased storm
intensity anticipated as a result of climate change, there are no models that project and quantify what these future
storm surges could be. Quantitative analyses of the likelihood of fewer, but more intense storms are as numerous as
those siting paleo data that indicates there will be fewer, less intense extreme storms (i.e. hurricanes). Thus, to
accurately address storm surge vulnerabilities for the City of Sarasota, our team will investigate a range of possible
storm surge scenarios using this NOAA tool that take into account historic storms, peak coincidence of storm surge,
astronomical tides, wind and waves, and water elevations that will be categorized through the measure of tropical
cyclone strength called the Saffir-Simpson scale (http://www.nhc.noaa.gov/aboutsshws.php).
As of May 12, 2010, storm surge potential for each category on the Saffir-Simpson scale was removed by the NOAA/
National Hurricane Center (NHC) due to NHC’s need to better convey information on a storm-by-storm basis. The
storm surge values associated with that scale, which were derived from climatological values for storms in each of the
categories, will still be useful as a guide for storm surge vulnerability modeling within the CFEM tool. Storms surges
associated with Category 1, 2, 3, 4, and 5 tropical cyclones will be used as input into this tool for geospatial
referencing of potential hazards to infrastructure.
4.1.3
Temperature
Recommended Assessment Tool:
NOAA National Climatic Data Center/Cooperative Institute for Climate and Satellites (http://www.ncdc.noaa.gov/)
Global climate change is expected to result in increased average temperatures thereby causing an increase in the
number of unusually hot days and a decrease in unusually cold days for our region. Temperature is often evaluated
from the perspective of heating and cooling needs for buildings and impacts on vulnerable populations such as the
young, the elderly and the homeless. Excessive heat can lead to increases in extreme rainfall events and increases in
atmospheric gases, such as water vapor, which can increase the atmosphere’s ability to retain heat causing further
discomfort. Extreme heat will result in public health concerns, urban heat islands, and temperature increases in
coastal waters such as Sarasota Bay, tidal creeks, estuaries, and gulf waters. Excessive heat and higher heat index
values (i.e. “feels like temperature”) can affect day-to-day life by increasing outdoor discomfort and increasing the
demand for temperature controls to cool buildings, which can lead to power outages. Extreme heat can also stress
infrastructure including an increase in costs for operation and maintenance of assets.
Current projections for the City of Sarasota suggest temperature maximums and minimums will increase by 3.6⁰F –
5.4⁰F by 2050. Based on this range of temperature changes from downscaled GCM projections, the Sarasota region is
expected to see the number of hot days (95°F or higher) increase by 50-60 days each year by 2050
(http://www.ncdc.noaa.gov/). This is expected to lead to an increase in air pollution and allergens, a reduction in
agricultural productivity, an increase in harmful algal blooms and diseases, biogeographic changes, impacts on
vulnerable populations, and an increase in the severity of rainfall events. We will use dynamically downscaled global
climate model output supplied by the NOAA National Climatic Data Center/Cooperative Institute for Climate and
Satellites (NOAA-NCDC/CICS) to quantify projections of future air temperatures in the region for use in this analysis.
November 2016
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The vulnerability assessment of changes in air temperatures due to climate change is far more complex than the
application of climate change projections for sea level rise, storm surge, and precipitation intensities. The impact to
infrastructure from changes in air temperatures can be significant and will be included in this analysis, but this threat
is far outweighed by the impact of these changes on human health and the human condition (Figure 15). Thus, the
identification of vulnerabilities within the City to future periods of extreme heat, due to the emphasis on health and
safety that this threat requires, will need to be discussed on a case-by-case basis based on input from City staff.
Figure 15: Inter-connectivity and Complexity of Identifying and Quantifying the Impact of Air
Temperature Increases/Extremes on a Community
Source: Center for Disease Control and Prevention/National Center for Environmental Health
4.1.4
Precipitation and Extreme Storms
Weather is as much a contributor to the success of our water management as it is a hazard to infrastructure
resilience. Effectively analyzing weather data greatly decreases the vulnerabilities natural hazards present and
increases operational efficiency of municipal infrastructure. To better grasp the vulnerability of the City’s stormwater
infrastructure, we will look at extreme events, as well as more frequent intense storm event periods, both having
unique impacts to the City’s infrastructure and accessibility. A critical step in identifying the potential for climaterelated risk is the identification of existing concerns that may or may not have been addressed.
PRECIPITATION
Recommended Assessment Tool:
NOAA Atlas 14 Point Precipitation Frequency Estimator (http://hdsc.nws.noaa.gov/hdsc/pfds/index.html)
According to NASA, average precipitation across the U.S. has increased by about five percent since 1900 however,
variations have been regional. The southeast has experienced a mix of increases and decreases. Projections suggest
continuation of the recent U.S. trend towards increased precipitation, including heavy extreme precipitation, but
overall distribution of rain will be variable with some regions expected to decrease (NASA, 2016).
November 2016
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GCM projections for yearly rainfall and for the likelihood for more intense rainfall events vary considerably for our
region and current models are not very skilled at predicting rainfall (current R2 of 0.42 when back calculated using
historic data from 1950-2000). In other words, while changes in rainfall intensity and rainfall accumulation is
occurring and is expected to increase, quantifying exactly what the increase will be for a given region is nebulous at
best. In lieu of taking GCM output verbatim from the four available RCPs, we propose to utilize the aforementioned
Clausius-Clapeyron equation with projected air temperature changes (much higher skill level) to determine what
factor to multiply current rainfall intensities/recurrence intervals by to develop a projection for the year 2050.
Most design criteria for infrastructure (i.e. roads, bridges, stormwater, etc.) in the U.S. is based on the rainfall return
frequencies from NOAA Atlas 14. These analyses are site-specific to any point on the GIS interface available online
through the NOAA Point Precipitation Frequency Estimator and can be generated for any point in the City of Sarasota.
Our team will identify representative rainfall values for the 5, 10, 25, and 100-year rainfall events over the city, and
then multiply these by the increase in anticipated rainfall intensities (factor) derived through the actions in the
previous paragraph, thereby developing a physics-based projection for increases in future rainfall intensities.
EXTREME STORMS
Recommended Assessment Tool(s):
NOAA’s Coastal Flood Exposure Mapper (https://coast.noaa.gov/digitalcoast/tools/flood-exposure)
NOAA Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model (http://www.nhc.noaa.gov/surge/slosh.php)
Sarasota County Stormwater Model (ftp://ftp.scgov.net/PUB/StormWater/Baysheds/SarasotaBay/)
Changes in storm frequency and intensity are areas of scientific study of particular interest to the southeast U.S. and
Florida since tropical cyclones gain energy from warm waters (>80⁰F ). According to the EPA, global average sea
surface temperatures (SST) have increased from a low in 1910 to 2015 levels, which are 2.625⁰F warmer. This steady
rise in SST is not only expected to continue, but is expected to be further exacerbated by projected warming air
temperatures. Thus, by 2050, Atlantic and Gulf of Mexico SST are expected to be at the least 1.3⁰F warmer, but could
be as much as 4⁰F or 5⁰F warmer. However, current studies and climate models leave uncertainty as to how climate
change will affect hurricane formation. Some studies suggest the Atlantic Multi-decadal Oscillation will drive natural
cyclical variations in hurricane formation, while others suggest climate warming will cause an increase in hurricane
formation and intensities (U.S. Global Change, 2014). Although a warmer atmosphere will lead to warmer ocean
temperatures and presumably an increase in formation of stronger storms, there is no consensus on how much or
whether there will be any impact on these extreme events.
What is certain? Hurricanes will continue to threaten the Florida Gulf Coast and the City of Sarasota into the
foreseeable future and damage from future tropical storms will be exacerbated not only by storm intensity, but also
by higher sea levels and storm surge. A recent example of a Category 1 storm is Hurricane Matthew that made
landfall in North Carolina in October 2016 causing deaths and extreme flooding 18 miles inland of the coast
emphasizing that factors other than storm intensity (e.g. direction of storm approach, speed of storm approach, the
point of landfall) come in to play when evaluating impacts to coastal shorelines. Notably, fewer storms typically curve
east to directly impact west-central Florida. Although many have come close and some have brushed the shorelines
of the City of Sarasota, the closest direct hit our region has had was from a Category 3 hurricane, known as the 1921
Tarpon Springs Hurricane, which made landfall near Tampa before heading east across the state. The most recent
storms to pass near the City included Tropical Storm Colin and Hurricane Hermine, both of which produced storm
surge, high winds and flooding.
November 2016
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Bayfront Park City of Sarasota - Hurricane Hermine
Hart’s Landing, City of Sarasota - Tropical Storm Colin
Our team plans on investigating the impacts of future extreme storm events by evaluating the impacts of hurricanes
based on the current levels of intensity identified in the Saffir-Simpson scale. Through these means, winds, storm
surge/inundation, heavy rainfall, and storm duration will all be accounted for in the vulnerability assessment. Since
there is little quantitative guidance on what future storms will look like other than a qualitative admission that they
may be more intense, the methodology should cover all bases by using categories of hurricanes 1 through 5 on this
scale. Analysis of the potential impacts to the city from extreme storm events will be viewed through NOAA’s Coastal
Flood Exposure Mapper for storm surge and the NOAA Sea, Lake, and Overland Surges from Hurricanes (SLOSH)
model for inundation. We will reference Sarasota County’s Stormwater Model as a tool to better understand flooding
and rainfall events throughout the City. The reporting of wind damage potential will require integration and the
sharing of institutional knowledge from city managers and local power companies.
5
Assessment of Vulnerable Infrastructure
In order to conduct the vulnerability assessment we will utilize existing infrastructure data and Global Information
System (GIS) ArcMap 10.4 to geo-spatially map the City’s critical infrastructure assets. We will use map
representations to conduct the vulnerability assessment and develop adaptation strategies. These maps will help
inventory assets to identify critical infrastructure and high-risk areas in the City and will provide the foundation to
model future flood hazards associated with three of the four climate variables including 1) sea level rise, 2) storm
surge (with sea level rise and waves), and 3) extreme storms/precipitation. The impact to infrastructure from
changes in air temperatures will also be included in this analysis. The identification of vulnerabilities to future periods
of extreme heat, due to the emphasis on health and safety that this threat requires, will need to be discussed on a
case-by-case basis and considered using institutional knowledge and reporting of previous episodes of extreme heat
in the region (i.e. July and August of 2016).
We will identify and quantify threats and stressors using scientific analysis, existing stormwater model outputs, and
resilience models (e.g. CREAT 3.0 https://www.epa.gov/crwu/build-climate-resilience-your-utility) to analyze risks and
vulnerabilities and determine failure modes and consequences to aid and inform climate-based impact decisions.
November 2016
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We will identify critical infrastructure assets throughout the City including:
5.1
•
Water Supply Facilities
•
Wastewater / Reclaimed Water Facilities
•
Stormwater Management Facilities
•
Transportation Infrastructure & Facilities
•
Coastal Protection (e.g. beaches, hardened and living shorelines, bay and estuaries)
Water Supply
We will assess the vulnerability of the City’s raw water sources to extreme drought and salt water intrusion by
reviewing the City’s historical raw water quality data in combination with climate predictions. The City’s water supply
originates from the Verna Well-Field located in northeastern Sarasota County about 17 miles east of the City. Landsurface topography at the wellfield ranges from 60 to 95 feet NGVD 1929 (USGS publication). The City also operates
downtown production wells, which may be impacted by the climate variables discussed above.
We expect to analyze the following water supply assets as part of this vulnerability assessment:
•
Water Treatment Facility (Lime Softening & Reverse Osmosis)
•
Water Storage Facilities
•
Raw Water Sources
o
Verna Wellfield
o
Downtown Raw Water Production Wells

Flood contamination

Electrical equipment
•
Deep Injection Wells
•
Sarasota Bay - Ionic Exchange Recharge Water
o
5.2
Salt Water Contamination / water quality
•
Major Transmission Mains critical to maintain service
•
Critical Power Sources/Backup Power
•
Hydraulic backpressure on coastal aquifers
o
Saltwater intrusion into water-supply wells
o
Groundwater levels
Wastewater and Reclaimed Water
The City of Sarasota Utilities Facility, including water and wastewater infrastructure, is located upstream of Hog Creek
less than 1-mile from the Sarasota Bay shoreline. We will inventory the city’s wastewater and reclaimed water assets
to determine critical vulnerabilities.
November 2016
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We expect to analyze the following wastewater and reclaimed water assets as part of this vulnerability assessment:
5.3
•
Wastewater Treatment Facility
•
Major Collection System Infrastructure (89 lift stations and associated force mains)
•
Reclaimed water system
•
Wet-weather deep injection wells
•
Pumps and motors
•
Inflow and infiltration (I&I) - Rainwater in collection system
•
Critical Power Sources/Backup Power
Stormwater
Stormwater management is critical for protecting built environments. This study will evaluate existing stormwater
management systems to understand the water quantity linkages with downstream systems, as well as frequency of
flooding in low-lying coastal developments. We expect to analyze the following stormwater assets as part of this
vulnerability assessment:
•
•
Spring and fall high tides in coincidence with storm events
Future extreme storms - strong onshore winds
•
Future storm surge and wave heights during hurricanes
•
Stormwater drainage systems relying on gravity will experience reduced effectiveness
•
Saint Armand’s Stormwater Pump Stations
•
Green Infrastructure
For this study, we will utilize the rainfall intensities that are
appropriate climate projections specific to our region. We
will reference Sarasota County’s Stormwater Model as a
tool to better understand flooding and rainfall events in the
City. Sarasota County developed a series of hydraulic
computer simulation models using the Streamline
Technologies Interconnected Channel and Pond Routing
(ICPR) software. This computer simulation was specifically
developed to evaluate the relatively unique rainfall events
in Florida. The model was developed for all of Sarasota
County’s baysheds, five of which fall within the City of
Sarasota limits: Hudson Bayou, Whitaker Bayou, Phillippi
Creek, Sarasota Bay Coastal, and Roberts Bay North.
Figure 16: City of Sarasota Baysheds
November 2016
22
For the County’s hydraulic model, the existing infrastructure was mapped and brought into the digital environment,
including surveyed measurements for stormwater pipes, structures, weirs, culverts, ponds, channels, and other
infrastructure designed to convey the stormwater. The model also included LiDAR (Light Detection and Ranging) data
to identify the topography within each bayshed. While this hydraulic model is an approximation or simulation, the
results have been verified by field measurements and provide a remarkably close estimation for post-storm drainage
conditions. The County ICPR models have proven to be the best available industry standard to predict flood stages
within the City of Sarasota and was recently adopted by the Federal Emergency Management Agency (FEMA) to
identify the insurance floodplain delineations.
We will use digital data from the County’s stormwater model to better understand the hydrological dynamics within
the five baysheds intercepting the City limits. We will use the data from the model to geo-spatially map the City’s
stormwater infrastructure and topography upon which we will simulate future climate change projections to identify
critical stormwater infrastructure in high risk zones throughout the City with vulnerabilities due to climate change.
5.4
Transportation
The City includes more than 500 miles of roads all within 5-miles from the coast including major arterials and
interstate connectors under State or County jurisdiction. These roads provide a critical link for the public during
evacuations and need to be evaluated with regard to flooding and long-term viability. A comprehensive
transportation infrastructure assessment must consider public access, emergency evacuation, road and bridge
integrity, safety, and alternative transportation such as pedestrian and bicyclist routes and water transportation. We
expect to analyze the following transportation assets as part of this vulnerability assessment:
November 2016
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Roads susceptible to washout and erosion
•
Bridges connecting coastal communities to each
other and barrier islands to mainland
•
Alternative Transportation
•
Railroads
•
Evacuation routes (Public and emergency
services)
•
Traffic control electrical boxes
•
Pedestrian Facilities
•
U.S. Coast Guard
•
Public Marinas, Anchorages, Boat Ramps
23
5.5
Coastal Protection
An infrastructure inventory must also consider coastal protection, which requires an understanding of the resiliency
of hardened shorelines, beaches, natural shorelines (e.g. mangroves), and ecosystem services (e.g. recreational
fisheries). As sea levels increase in elevation along the Gulf Coast, barrier islands and bays will change, which will
alter the dynamics between the Gulf beaches and tidal inlets. Shoreline infrastructure such as seawalls are expected
to become increasingly susceptible to flood damage, storm surge, and wave impacts as these conditions are
compounded by rising seas. Factors to consider during the infrastructure vulnerability assessment include options to
harden shorelines, expand living shorelines, elevate land, and retrofit, relocate or abandon infrastructure.
6
Summary and Next Steps
The purpose of this Technical Memorandum was to summarize scientific information and resources addressing
climate change vulnerabilities for our region and identify the latest climate science and industry models available for
conducting the City of Sarasota Climate Change Vulnerability Assessment and Adaptation Plan. This Step 1 deliverable
has endeavored to set the foundation on which to build for modeling the City’s infrastructure vulnerabilities to SLR,
surge, heat and extreme precipitation. A synopsis of potential changes in global and local climate is provided in
Figure 17.
Figure 17: Summary of Global and Regional Climate Scenarios
November 2016
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Following completion of Step 1, we will begin the infrastructure mapping associated with Step 2, which will involve an
inventory of the City’s water, waste water, stormwater and transportation assets and a review of infrastructure
reports, maintenance logs, and record drawings to enable us to identify (in collaboration with the City’s infrastructure
managers) at-risk municipal systems. We will map and inventory the City’s infrastructure assets using existing
georeferenced GIS data. Step 3 will involve a vulnerability assessment of affected infrastructure and the application
of climate projections to identify risks to critical City infrastructure. Step 4 will include an evaluation of the risks and
vulnerabilities to critical municipal systems to determine failure modes and consequences and prioritization of
vulnerabilities in cooperation with City. This will lead to Step 5 where we will develop and strategize adaptation
strategies to reduce infrastructure vulnerabilities and determine adaptation strategies to incorporate into the City’s
Climate Change Adaptation Plan. After reaching consensus with the City and presenting the infrastructure
vulnerability assessment to the public, a Climate Adaptation Plan will be provided to the City to conclude Step 6.
The City of Sarasota understands that developing resilience to climate change is necessary to mitigate infrastructure
vulnerabilities to natural and man-made hazards and recognizes it has a responsibility to protect public health and
safety by ensuring resiliency of municipal infrastructure. The Climate Change Vulnerability Assessment and
Adaptation Plan will result in a comprehensive assessment of critical infrastructure vulnerabilities and development of
adaptation measures to inform decisions that address near and long-term threats associated with those changes to
enhance community resilience.
Sunny Day at Bayfront Park, City of Sarasota
November 2016
Bayfront Park following Hurricane Hermine
25
7
References
Carter, L. M., J. W. Jones, L. Berry, V. Burkett, J. F. Murley, J. Obeysekera, P. J. Schramm, and D. Wear, 2014: Ch. 17:
Southeast and the Caribbean. Climate Change Impacts in the United States: The Third National Climate Assessment, J.
M. Melillo, Terese (T.C.) Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 396-417.
doi:10.7930/J0N-P22CB.
Center for Disease Control. Climate Change and Extreme Heat Events.
http://www.cdc.gov/climateandhealth/pubs/ClimateChangeandExtremeHeatEvents.pdf
City of Sarasota Flood Management Plan 2015-2020. http://sarasotagov.org/PDF/NDS/FloodplainMgmtPlan2015-2020.pdf
EPA. https://www.epa.gov/sites/production/files/2016-08/documents/print_heating-cooling-2016.pdf
EPA. https://www.epa.gov/climate-indicators/climate-change-indicators-high-and-low-temperatures
Florida Climate Center. An Analysis of the Beginning, End, Length, and Strength of Florida’s Hot Season.
https://climatecenter.fsu.edu/topics/specials/floridas-hot-season
Florida Oceans and Coastal Council (FOCC). 2009. Climate Change and Sea-Level Rise in Florida: An Update of “The Effects of
Climate Change on Florida’s Ocean and Coastal Resources.” Tallahassee, FL vi+26 p. www.floridaoceanscouncil.org.
Kemp, A.C., Horton, B.P., Donnelly, J.P., Mann, M.E., Vermeer, M., Rahmstorf, S. 2011. Climate related sea-level variations
over the past two millennia. PNAS vol. 108:27. p. 11017–11022. www.pnas.org/cgi/doi/10.1073/pnas.1015619108
NASA's Jet Propulsion Laboratory | California Institute of Technology. 2016. http://climate.nasa.gov/effects/.
National Climate Assessment. http://nca2014.globalchange.gov/report/regions/southeast.
NOAA National Climatic Data Center/Cooperative Institute for Climate and Satellites. http://www.ncdc.noaa.gov/
NOAA Office for Coastal Management. https://coast.noaa.gov/data/docs/states/shorelines.pdf
NOAA Office for Coastal Management.
https://www.st.nmfs.noaa.gov/st5/publication/communities/Gulf_Summary_Communities.pdf
Sarasota County Stormwater Model (ftp://ftp.scgov.net/PUB/StormWater/Baysheds/SarasotaBay/)
U.S. Environmental Protection Agency. Climate Change Indicators: Sea Surface Temperature.
https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature
U.S. Global Change Research Program. 2014. http://www.globalchange.gov/about/site-credits
Weisberg, R.H., L. Zheng. 2006. Hurricane Storm Simulations for Tampa Bay. Estuaries and Coasts vol. 29:6. p. 899-913.
U.S. Geological Survey Water Resources Division. Hydrologic Records, Verna Well-Field Area, City of Sarasota, Florida, 196276 A Data Report. Accessed from http://pubs.usgs.gov/of/1979/1259/report.pdf.
Recommended Assessment Tools
NOAA Digital Coast Sea Level Rise Mapper (https://coast.noaa.gov/digitalcoast/tools/slr)
NOAA’s Coastal Flood Exposure Mapper (https://coast.noaa.gov/digitalcoast/tools/flood-exposure)
NOAA National Climatic Data Center/Cooperative Institute for Climate and Satellites (http://www.ncdc.noaa.gov/)
NOAA Atlas 14 Point Precipitation Frequency Estimator (http://hdsc.nws.noaa.gov/hdsc/pfds/index.html)
NOAA Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model (http://www.nhc.noaa.gov/surge/slosh.php)
EPA CREAT 3.0 https://www.epa.gov/crwu/build-climate-resilience-your-utility
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