(Table 2). Naturally, low-lying coastal areas are most sensitive, including deltas,
low-lying coastal plains, coral islands, beaches, barrier islands, coastal wetlands,
and estuaries. The actual impacts will depend on human management, For
instance, increased flooding and inundation of coastal lowlands will promote
wetland creation, while protection of coastal lowlands will exacerbate wetland
losses, as no replacement of losses will occur. Selected biogeophysical effects are
now considered in more detail.
Inundation, floods and storm damage. Inundation (i.e. permanent submergence)
of the Maldives and large parts of Bangladesh due to sea-level rise was one of the
first forecasts that alerted the world community to the threat of human-induced
climate change. More generally, deltas and coral islands were recognized as
being highly threatened by the effects of sea-level rise due to their low elevation.
However, before an area is inundated, it will first experience an increasing
frequency of flooding (i.e. temporary submergence) and storm damage as the
existing flood plain is flooded more frequently, and the flood plain expands in
size. This effect will occur for both surges and river floods of coastal
lowlands. Therefore, while most analyses distinguish inundation and increased
flooding as distinct processes, they are part of a continuum.
Deltas form near sea level where river-deposited sediment accumulates in the
coastal zone, and hence provide a good example of threatened coastal lowlands.
Deltaic areas can often keep pace with rising sea level by riverborne sedimentation.
However, delta management often excludes floods, while upstream dams reduce
sedimentary inputs. Hence this is an example of human management
increasing vulnerability of coastal areas to sea-level rise. Sustaining sediment
supply and developing flood management approaches that allow sedimentation
are two approaches that could assist delta survival under sea-level rise based on a
‘working with nature’ philosophy.
Wetland loss (and change). Coastal wetlands (saltmarsh, mangroves and
unvegetated intertidal mud) are sensitive to long-term sea-level change as their
location is intimately linked to sea level. In response to sea-level rise, coastal
wetlands experience faster vertical accretion due to increased sediment and
J. M. Broadus, J. D. Milliman, S. F. Edwards, D. C. Aubrey and F. Gable, Rising sea level and
damming of rivers: possible effects in Egypt and Bangladesh, in J. G. Titus (ed.), Effects of Changes
in Stratospheric Ozone and Global Change, Volume 4, US Environmental Protection Agency,
Washington DC, 1986, pp. 165—189.
Commonwealth Secretariat, Expert Group on Climate Change and Sea-Level Rise. Commonwealth
Secretariat, London, 1989, 230 pp.
R. J. Nicholls, An analysis of the flood implications of the IPCC Second Assessment global
sea-level rise scenarios, in D. J. Parker (ed.), Floods, Routledge, London, 2000, pp. 148—162.
D. F. Boesch, M. N. Josselyn, A. J. Mehta, J. T. Morris, W. K. Nuttle, C. A. Simenstad and D. J. P.
Swift, Scientific assessment of coastal wetland loss, restoration and management in Louisiana, J.
Coastal Res., 1994, Special Issue No. 20.
A. Sanchez-Arcilla, J. Jimenez and H. I. Valdemoro, The Ebro delta: morphodynamics and
vulnerability, J. Coastal Res., 1998, 14, 754—772.
R. J. Nicholls
94
low-lying coastal plains, coral islands, beaches, barrier islands, coastal wetlands,
and estuaries. The actual impacts will depend on human management, For
instance, increased flooding and inundation of coastal lowlands will promote
wetland creation, while protection of coastal lowlands will exacerbate wetland
losses, as no replacement of losses will occur. Selected biogeophysical effects are
now considered in more detail.
Inundation, floods and storm damage. Inundation (i.e. permanent submergence)
of the Maldives and large parts of Bangladesh due to sea-level rise was one of the
first forecasts that alerted the world community to the threat of human-induced
climate change. More generally, deltas and coral islands were recognized as
being highly threatened by the effects of sea-level rise due to their low elevation.
However, before an area is inundated, it will first experience an increasing
frequency of flooding (i.e. temporary submergence) and storm damage as the
existing flood plain is flooded more frequently, and the flood plain expands in
size. This effect will occur for both surges and river floods of coastal
lowlands. Therefore, while most analyses distinguish inundation and increased
flooding as distinct processes, they are part of a continuum.
Deltas form near sea level where river-deposited sediment accumulates in the
coastal zone, and hence provide a good example of threatened coastal lowlands.
Deltaic areas can often keep pace with rising sea level by riverborne sedimentation.
However, delta management often excludes floods, while upstream dams reduce
sedimentary inputs. Hence this is an example of human management
increasing vulnerability of coastal areas to sea-level rise. Sustaining sediment
supply and developing flood management approaches that allow sedimentation
are two approaches that could assist delta survival under sea-level rise based on a
‘working with nature’ philosophy.
Wetland loss (and change). Coastal wetlands (saltmarsh, mangroves and
unvegetated intertidal mud) are sensitive to long-term sea-level change as their
location is intimately linked to sea level. In response to sea-level rise, coastal
wetlands experience faster vertical accretion due to increased sediment and
J. M. Broadus, J. D. Milliman, S. F. Edwards, D. C. Aubrey and F. Gable, Rising sea level and
damming of rivers: possible effects in Egypt and Bangladesh, in J. G. Titus (ed.), Effects of Changes
in Stratospheric Ozone and Global Change, Volume 4, US Environmental Protection Agency,
Washington DC, 1986, pp. 165—189.
Commonwealth Secretariat, Expert Group on Climate Change and Sea-Level Rise. Commonwealth
Secretariat, London, 1989, 230 pp.
R. J. Nicholls, An analysis of the flood implications of the IPCC Second Assessment global
sea-level rise scenarios, in D. J. Parker (ed.), Floods, Routledge, London, 2000, pp. 148—162.
D. F. Boesch, M. N. Josselyn, A. J. Mehta, J. T. Morris, W. K. Nuttle, C. A. Simenstad and D. J. P.
Swift, Scientific assessment of coastal wetland loss, restoration and management in Louisiana, J.
Coastal Res., 1994, Special Issue No. 20.
A. Sanchez-Arcilla, J. Jimenez and H. I. Valdemoro, The Ebro delta: morphodynamics and
vulnerability, J. Coastal Res., 1998, 14, 754—772.
R. J. Nicholls
94