Part C | 25.1
554 Part C Coastal Design
Table 25.1 Observed sea-level rise rates at selected locations (adapted from [25.42])
Location
Time
period
Sea-level rise
rate [mm=yr]
Dublin, Ireland
19382001
0.21
Aberdeen, Great Britain
19322010
1.01
Helsinki, Finland
19002010
2:08
Oslo, Norway
19162010
3:75
Stockhold, Sweden
19002010
3:80
Kiel, Germany
19562010
1.45
Marseille, France
19002009
1.19
Venice, Italy
19092000
2.40
Karachi, Pakistan
19371986
0.41
Mumbai, India
19002006
0.83
Gangra, India
19742006
1.19
Quinhon, Vietnam
19772006
1:27
Hong Kong, China
19632010
2.71
Shanghai, China
19612010
5.01
Pusaon, Korea
19612009
2.03
Tokyo, Japan
19302010
3.60
Nagasaki, Japan
19652010
2.19
Singapore
19542010
0:91
Brisbane, Australia
19662010
0.21
Sydney, Australia
19152010
0.90
Auckland, New Zealand
19041998
1.26
Victoria, Canada
19102010
0.61
Quebec, Canada
19112010
0:38
Los Angeles, USA
19242010
0.86
San Francisco, USA
19002010
1.91
New York, USA
19002010
3.03
Washington DC, USA
19312010
2.99
Juneau, USA
19362010
13:05
Houston, TX
19582010
6.73
Buenos Aires, Argentina
19051987
1.54
Montevideo, Uruguay
19542009
0.92
La Libertad, Ecuador
19502002
1:31
Balbao, Panama
19082006
1.64
the next century [25.48]. The impact of SST on future
tropical cyclone rate-of-occurrence is not as well understood. Various analyses of the historical record reached
conclusions ranging from no significant change [25.47]
to an increase [25.49, 50] in tropical-cyclone activity
with the SST rise. Bender et al. [25.51] summarized
that for a mid-range carbon emissions scenario, climate
models showed a decrease in Atlantic tropical cyclone
activity, of 4 to 49%, by the 2100s, while most models showed an change for the most intense cyclones,
between 53 and C110%.
A future increase in storm intensity means that,
when storms do occur, storm wave and surge heights
will likely be larger [25.41, 52–58]. Thus, we can expect future coastal storm impacts, including inundation
elevation, and extent, wave and wind loading, erosion,
and damages to be more severe [25.59–63].
25.1.4 Anthropogenic Activities
Coastal urbanization can lead to unintended, unmitigated increases in coastal hazard risk, exacerbating the
need for improved coastal planning to mitigate such
hazard impacts. Consider, for example, the low-lying
and flood-prone New Orleans region in the United
States. To stabilize the Mississippi River mouth, an
important navigation waterway connecting the port of
New Orleans with much of the United States, and to
manage coastal flooding, a complex system of levees
and polders was designed and constructed throughout
the region over the last century. Recent studies show
that under certain storm conditions, levees used to control the river may enhance and trap storm surge, thereby
increasing flood-related damages [25.64]. As another
example of unintended consequences in this area, the
population of New Orleans grew more than 60% during
the 20th century [25.65], with many residents now settling in areas behind levees, at elevations below the sea
level. During Hurricane Katrina (2005), several levees
breached, leading to widespread flooding of these populated, low-lying areas. While the devastating impacts of
levee failure during Hurricane Katrina can be attributed
to a combination of factors, including design load exceedance, this event made clear the need to better plan
urban development to avoid urban growth in vulnerable
locations.
Another example of the impact of development at
the coast is the unintended consequences of construction of inland dams, mining of sediments from inland
rivers and waterways, and urbanization that hardens the
landscape. All of these processes impede the natural
movement of sediments to the coast [25.66], resulting in a depletion of the natural sediment supply and
contributing to widespread shoreline recession. Similarly, coastal erosion and navigation measures put in
place without considering that the downdrift impacts
often lead to unnecessary shoreline erosion. Recently,
regional sediment management techniques have been
used to manage coastal and inland sediment zones
holistically [25.67].
There is also the danger of a major industrial accident, which leads to adverse environmental impacts
at the coast. Recently, the Deepwater Horizon offshore
platform explosion in 2010 released a 35 km-long
plume of oil into the Gulf of Mexico [25.68]. Oil made
its way to the coast, damaging the coastal ecosystem.
This event directly impacted both tourism and commercial fishing in the region. The proliferation of oil refineries, nuclear power plants, chemical manufacturing
plants, and other such major industrial developments in
coastal areas must be carefully considered within this
fragile and dynamic environment.
554 Part C Coastal Design
Table 25.1 Observed sea-level rise rates at selected locations (adapted from [25.42])
Location
Time
period
Sea-level rise
rate [mm=yr]
Dublin, Ireland
19382001
0.21
Aberdeen, Great Britain
19322010
1.01
Helsinki, Finland
19002010
2:08
Oslo, Norway
19162010
3:75
Stockhold, Sweden
19002010
3:80
Kiel, Germany
19562010
1.45
Marseille, France
19002009
1.19
Venice, Italy
19092000
2.40
Karachi, Pakistan
19371986
0.41
Mumbai, India
19002006
0.83
Gangra, India
19742006
1.19
Quinhon, Vietnam
19772006
1:27
Hong Kong, China
19632010
2.71
Shanghai, China
19612010
5.01
Pusaon, Korea
19612009
2.03
Tokyo, Japan
19302010
3.60
Nagasaki, Japan
19652010
2.19
Singapore
19542010
0:91
Brisbane, Australia
19662010
0.21
Sydney, Australia
19152010
0.90
Auckland, New Zealand
19041998
1.26
Victoria, Canada
19102010
0.61
Quebec, Canada
19112010
0:38
Los Angeles, USA
19242010
0.86
San Francisco, USA
19002010
1.91
New York, USA
19002010
3.03
Washington DC, USA
19312010
2.99
Juneau, USA
19362010
13:05
Houston, TX
19582010
6.73
Buenos Aires, Argentina
19051987
1.54
Montevideo, Uruguay
19542009
0.92
La Libertad, Ecuador
19502002
1:31
Balbao, Panama
19082006
1.64
the next century [25.48]. The impact of SST on future
tropical cyclone rate-of-occurrence is not as well understood. Various analyses of the historical record reached
conclusions ranging from no significant change [25.47]
to an increase [25.49, 50] in tropical-cyclone activity
with the SST rise. Bender et al. [25.51] summarized
that for a mid-range carbon emissions scenario, climate
models showed a decrease in Atlantic tropical cyclone
activity, of 4 to 49%, by the 2100s, while most models showed an change for the most intense cyclones,
between 53 and C110%.
A future increase in storm intensity means that,
when storms do occur, storm wave and surge heights
will likely be larger [25.41, 52–58]. Thus, we can expect future coastal storm impacts, including inundation
elevation, and extent, wave and wind loading, erosion,
and damages to be more severe [25.59–63].
25.1.4 Anthropogenic Activities
Coastal urbanization can lead to unintended, unmitigated increases in coastal hazard risk, exacerbating the
need for improved coastal planning to mitigate such
hazard impacts. Consider, for example, the low-lying
and flood-prone New Orleans region in the United
States. To stabilize the Mississippi River mouth, an
important navigation waterway connecting the port of
New Orleans with much of the United States, and to
manage coastal flooding, a complex system of levees
and polders was designed and constructed throughout
the region over the last century. Recent studies show
that under certain storm conditions, levees used to control the river may enhance and trap storm surge, thereby
increasing flood-related damages [25.64]. As another
example of unintended consequences in this area, the
population of New Orleans grew more than 60% during
the 20th century [25.65], with many residents now settling in areas behind levees, at elevations below the sea
level. During Hurricane Katrina (2005), several levees
breached, leading to widespread flooding of these populated, low-lying areas. While the devastating impacts of
levee failure during Hurricane Katrina can be attributed
to a combination of factors, including design load exceedance, this event made clear the need to better plan
urban development to avoid urban growth in vulnerable
locations.
Another example of the impact of development at
the coast is the unintended consequences of construction of inland dams, mining of sediments from inland
rivers and waterways, and urbanization that hardens the
landscape. All of these processes impede the natural
movement of sediments to the coast [25.66], resulting in a depletion of the natural sediment supply and
contributing to widespread shoreline recession. Similarly, coastal erosion and navigation measures put in
place without considering that the downdrift impacts
often lead to unnecessary shoreline erosion. Recently,
regional sediment management techniques have been
used to manage coastal and inland sediment zones
holistically [25.67].
There is also the danger of a major industrial accident, which leads to adverse environmental impacts
at the coast. Recently, the Deepwater Horizon offshore
platform explosion in 2010 released a 35 km-long
plume of oil into the Gulf of Mexico [25.68]. Oil made
its way to the coast, damaging the coastal ecosystem.
This event directly impacted both tourism and commercial fishing in the region. The proliferation of oil refineries, nuclear power plants, chemical manufacturing
plants, and other such major industrial developments in
coastal areas must be carefully considered within this
fragile and dynamic environment.