HomeMy WebLinkAboutExhibit G - MCNP - Appendix CM-1Exhibit G
APPENDIX CM-1
The following map series indicate the adopted coastal features not depicted on the 2424 2035 Future Land Use
Map. The following maps include "CM-1: Flood Zones Federal Emergency Management Administration", "CM-2:
Coastal High Hazard Area, "CM-3: 2040 Inundation Risk", and "CM-4: 2060 Inundation Risk".
This space was intentionally left blank.
Miami Comprehensive Neighborhood Plan
Goals Objectives Policies
October 2022 XXXX
Map CM-1: Flood Zones
Federal Emergency Management Administration
CI OWEl
0 AE 0
0 VE 0
0 AH
X
X-500
PCT
City Boundary
0
N
1
2 Miles
1
Created by the City of Miami Planning Department
December 15, 2019
N:\Planning\GI S\Resilience_Mapping\MXD
Sources: Miami Dade County aerial and LiDAR
Map CM-2: Coastal High Hazard Area
® Coastal High Hazard Area*
0 City Boundary
*As defined in Coastal Management
Element Policy CM-4.1.2
0
N
2 Miles
Created by the City of Miami Planning Department
October 2022
N:\Planning\GI S\Resi lience_Mappi ng\MXD
Sources: Miami Dade County LiDAR; SLOSH
Map CM-3: 2040 Inundation Risk
The Coastal High Hazard Area (CHHA), as defined in Section
163.3178(2)(h)9, Florida Statutes, covers the area that is below
the elevation of the category 1 storm surge line. The CHHA is the
area particularly vulnerable to the effects of tropical storm events.
This map analyzes the extent of the CHHA, accounting for sea
level rise, using the Unified Sea Level Rise projection from the
Southeast Florida Regional Climate Change Compact.
PCC 2040
NOAA 2040
0
2 Miles
Created by the City of Miami Planning Department
September 2022
N:\Planning\GI S\Resilience_Mapping\MXD
Sources: Miami Dade County aerial and LiDAR
The Unified Sea Level Rise projection uses multiple sources
in order to create a range of outlooks, from conservative to
aggressive. The Intergovernmental Panel on Climate
Change (IPCC), through its Fifth Assessment Report, predicts a
more conservative amount of sea level rise. On the aggressive
end of the projection, the National Oceanic and Atmospheric
Administration (NOAA) predicts a greater rate of sea level rise.
The description of these data can be found in this appendix.
SW 8TH ST
S F44.1.2
NW-1.1•THST'
SWI6TH ST
SW 22ND ST
BIRD AVE
SW 7TH AT
z
NW 54TH ST
NW 46TH ST
NW-29TH.SjT
z 1
NE 62ND.ST
5_
a
2
_ RIGKENBAGKERWGSW
VENETIAN
CSWY
11
Map CM-4: 2060 Inundation Risk
The Coastal High Hazard Area (CHHA), as defined in Section
163.3178(2)(h)9, Florida Statutes, covers the area that is below
the elevation of the category 1 storm surge line. The CHHA is the
area particularly vulnerable to the effects of tropical storm events.
This map analyzes the extent of the CHHA, accounting for sea
level rise, using the Unified Sea Level Rise projection from the
Southeast Florida Regional Climate Change Compact.
I PCC 2060
NOAA 2060
0
1 2 Miles
Created by the City of Miami Planning Department
September 2022
N:\Planning\GI S\Resilience_Mapping\MXD
Sources: Miami Dade County aerial and LiDAR
The Unified Sea Level Rise projection uses multiple sources
in order to create a range of outlooks, from conservative to
aggressive. The Intergovernmental Panel on Climate
Change (IPCC), through its Fifth Assessment Report, predicts a
more conservative amount of sea level rise. On the aggressive
end of the projection, the National Oceanic and Atmospheric
Administration (NOAA) predicts a greater rate of sea level rise.
The description of these data can be found in this appendix.
NW 7TH ST
W FLAGLER ST
SW 22ND ST
GRAND
NW 87TH ST
o•.
>
NW 36TH ST 00.I'195
w =
z
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a n ,
X 7
w
rn
NE`20TH`ST y
-3g 5
5 RICKENBACKERCSWY
KENNED.Y,CSWY
VENETIAN
CSWY
Appendix CM-1 Coastal Management Element
Updating the Coastal High Hazard Area and Projecting Sea Level Rise
in the Miami Comprehensive Neighborhood Plan
1. Modeling the Coastal High Hazard Area
Florida Statutes require the designation of the Coastal High Hazard Area (CHHA) within every
city with a Coastal Management Element in its comprehensive Plan, pursuant to Section
163.3178(2)(h), F.S. This section defines the CHHA thus:
[T]he area below the elevation of the category 1 storm surge line as established by a
Sea, Lake, and Overland Surges from Hurricanes (SLOSH) computerized storm surge
model.
It is important to note here that this designation is entirely different and unassociated with the
Federal Emergency Management Administration's own "Coastal High Hazard Area" designation,
which is related to the specific flood zones applied to the Flood Insurance Rate Maps. The
CHHA as designated here and defined by State statute is meant to be a planning tool for growth
management in coastal areas.
The City of Miami's Coastal High Hazard Area (CHHA): Methodology
As required by the referenced statute, the CHHA is created using an inundation model (a
SLOSH model from the National Weather Service), combined with high -resolution elevation
data. A Geographic Information System was used to process the data and produce the maps by
which the data are analyzed.
Data Sources
The main data are described below:
1. SLOSH Model — The Sea, Lake and Overland Surges from Hurricanes (SLOSH) Model
from the National Weather Service estimates surge heights and the extent of storm
surge at various points along coastal areas with chosen atmospheric conditions. The
SLOSH model is a polygon feature comprised of grid cells with a numerical value
representing storm surge heights. For this reason, SLOSH models alone are not
sufficient to create the CHHA. Nevertheless, statue requires an examination of these
data, assuming a Category 1 hurricane making landfall. This model is a generalized
model and it does not take elevation or local hydrology into account. For more
information about the SLOSH Model, please refer to the National Oceanic and
Atmospheric Administration: https://www.nhc.noaa.gov/surge/slosh.php.
2. Elevation Data — For the creation of the CHHA, the City of Miami used high -resolution
Light Detecting and Ranging (LIDAR) data. LIDAR is created using high -frequency
lasers to measure elevation over an area. These data are accessible to the public
through Miami -Dade County's Open Data portal:
https://mdc.maps.arcgis.com/home/item.html?id=32f1 de78447c4c958782b1 b2b5d47369
1 October 2022
Appendix CM-1 Coastal Management Element
3. Local Hydrology — The City of Miami and Miami -Dade County maintain local hydrology
data, which maps local waterways and waterbodies. These data are accessible to the
public through Miami -Dade County's Open Data portal: https://gis-
mdc.opendata.arcgis.com/datasets/water-g?geometry=-80.237%2C25.768%2C-
80.183%2C25.775
The process of creating the CHHA combines these three data to model the area that is likely to
be inundated in a Category 1 hurricane making local landfall. The steps are as follows:
1. A SLOSH model is obtained for a direct landfall on the City of Miami by a Category 1
hurricane. Once retrieved, the SLOSH model must be converted into a point feature to
interpolate the data. This allows the GIS to stitch together the storm surge heights that
more accurately reflects the flow of water.
2. Using Spatial Analyst tools in ArcGIS, this model is then layered onto the LIDAR data to
determine the extent of inundation over land. More specifically, the elevation data were
"subtracted" from the interpolated SLOSH model, revealing those areas where the level
of storm surge was above the ground elevation.
3. Once the extent of the inundation was produced from the combination of these two data,
the resulting polygon was analyzed against the local hydrology. This was an important
step in storm surge modeling, as it helped to differentiate low-lying areas that may
experience some localized pooling of water from the low-lying areas that are directly
exposed to open water, and thus, at risk from storm surge. At this point, areas that may
have been modeled to be within the projected extent of surge but with no possible
hydrological connection for the surge to follow were removed.
As updates to the data become available, the City will continue using this process to analyze the
CHHA. This will allow the City to continue long-range planning efforts with the most up-to-date
information.
2. Modeling Inundation Risk with Sea Level Rise
Future models for storm surge inundation are included here to account for sea level rise
projections through 2040 and 2060, for future land use planning within the comprehensive plan.
The method for the analysis is very similar to the method used to create the Coastal High
Hazard Area. Below is a description of the additional steps and data needed to create these
models, as well as a brief overview of the chosen projections for sea level rise.
2 October 2022
Appendix CM-1 Coastal Management Element
Using the Unified Sea Level Rise Projection from the Southeast Florida Regional Climate
Change Compact
The City of Miami is a member of the Southeast Florida Regional Climate Change Compact
("Compact"), a coalition of municipal agencies from Monroe, Miami -Dade, Broward, and Palm
Beach Counties devoted to advancing
policy to address the impacts of climate
change, including sea level rise. The
Compact adopts its Unified Sea Level
Rise Projection' (USLRP) as the
standard measure by which local
agencies and municipalities can plan for
their communities in the age of sea level
rise in a way that is coordinated
regionally. That projection uses models
from multiple international agencies. The
Intergovernmental Panel on Climate
Change's Fifth Assessment Report
contains a range of projections2. Of
these projections, the median projection
for sea level rise was chosen by the
Compact as the lower end of the
USLRP. The U.S. Army Corps of
Engineers, with an overall more
conservative projection, was chosen for
its high -end projection as the mid -point for the USLRP. For the high end of the USRLP, the
National Oceanic and Atmospheric Administration's own high -end projection was chosen.
Time
Sea Level Rise (inches) at Key West
IPCC AR5 Median USACE NOAA High
(0.73m) High (1.5m) (2m)
1992 0.0 0.0 0.0
2000 0.8 1.0 1.1
2010 2.2 3.0 3.6
2020 3.8 5.9 7.2
2030 6.0 9.7 12.1
2040 8.4 14.4 18.2
2050 11.3 19.9 25.7
2060 14.4 26.4 34.2
2070 18.0 33.8 44.0
2080 22.0 42.0 55.1
2090 26.2 51.1 67.3
2100 30.8 61.2 80.9
2110 35.9 72.1 95.6
2120 41.3 83.9 111.5
Accounting for Sea Level Rise in the Storm Surge Inundation Models
The principal difference between the codified Coastal High Hazard Area and the 2040 and 2060
storm surge inundation models with sea level rise is the adjustment of Mean Sea Level for the
data output from the SLOSH model:
Using the projections from the USLRP, in the table above, for the years 2040 and 2060, the
SLOSH model output was adjusted to account for sea level rise. That is Mean Sea Level is
adjusted for each of the projections, based on the chosen years. For the IPCC model, Mean
Sea Level is adjusted for 8.4 inches of sea level rise. This adjustment is made to the raw
SLOSH grid values for each of the models, based on the specific year. For this modeling, both
IPCC Median and NOAA High projections are used, with the 2040 and 2060 values added to
reflect the projected sea level rise.
1 Accessed at: https://southeastfloridaclimatecompact.org/wp-content/uploads/2015/10/2015-Compact-Unified-
Sea-Level-Rise-Proiection.pdf Southeast Florida Regional Climate Change Compact, Unified Sea Level Rise
Projection, October 2015
2 This report is accessible at: https://www.ipcc.ch/assessment-report/ar5/.
3 October 2022
Appendix CM-1 Coastal Management Element
3. Areas at risk in Miami
The maps included in Appendix CM-1, maps CM-2, CM-3 and CM-4, show areas at various
degrees of risk of storm surge inundation. Map CM-2 is the current Coastal High Hazard Area
and maps CM-3 and CM-4 use the same methods with the addition of projected sea level rise to
model areas at risk in 2040 and 2060. The three maps together compare the changes as sea
levels continue to rise, based on projections. On maps CM-3 and CM-4, the modeled storm
surges based on the two, chosen sea level rise projections are represented by different colors:
the International Panel on Climate Change in blue and the National Oceanic and Atmospheric
Administration in purple.
The analysis, accounting for those low-lying areas with connection to the local hydrology,
reveals the likeliest path of water from a storm surge. For example, a higher -elevation "ridge"
runs parallel to the Miami River, along the south bank. This is illustrated by pockets of land that
are not projected to be inundated by storm surge, despite sea level rise, up to 2060.
This analysis reveals the growing threat of sea level rise to neighborhoods across the City of
Miami. Within the City of Miami's boundaries, there are 23,086 acres of uplands around or
above sea level. Of that area, approximately 2,944 acres are contained within the 2040 at -risk
area and approximately 5,072 acres are contained within the 2060 at -risk area. The total
breakdown of area covered by the various projections are listed in the table below:
City of Miami Storm Surge Risk Analysis
with Sea Level Rise
Acres (2040) Percent (2040) Acres (2060) Percent (2060)
IPCC 1,760 8% 2,230 10%
NOAA 2,944 13% 5,072 22%
The table above shows the projected changes in sea level from the International Panel on Climate Change (IPCC), using its median
projection, and the National Oceanic and Atmospheric Administration (NOAA), using its high projection. The two projections were
chosen to show a range of potential impacts. The numbers are compared against the total acreage of upland areas in the city.
Within city boundaries, there are 23,086 acres that are upland from Biscayne Bay and the Miami River.
The largest increase in areas projected to be inundated between the 2040 and 2060 time
horizons are seen through the NOAA projection. While the IPCC Median only projects an
increase of two percent of lands being inundated, the NOAA High projects an additional nine
percent of land being inundated.
As illustrated on maps CM-3 and CM-4, areas along the Miami River will face these increasing
threats from storm surge due to sea level rise over time. While sea level rise will exacerbate
damage all along the City's coast, the Miami River and Blue Lagoon areas will see the greatest
increase in land threatened by storm surge. That is, of the total acreage of land that will face
threats of storm surge in the future due to sea level rise where there was no threat before, the
majority of that land lies along the Miami River and the Blue Lagoon.
The ridge running along coastal Miami, composed of oolite limestone, generally impedes any
major extension of sea level rise induced storm surge. This is a natural protective barrier for
areas behind that coastal ridge.
4 October 2022
Appendix CM-1 Coastal Management Element
The same type of protective ridge is absent for most of the Miami River and Little River basins.
There are a couple exceptions, like those mentioned above, where the limestone formation rises
high enough to keep some land above the Category 1 threshold but these areas are not
contiguous and do not provide a true barrier to storm surge, as the water may travel between
them and inundate areas further inland.
5 October 2022