Many managed realignment projects have re-creation
of intertidal habitats as a primary objective. This approach
is partially driven by the need to address statutory duties
(e.g., the EU Habitats Directive) to take all necessary measures to avoid detrimental impact to designated conservation areas and provide compensation for loss of these
habitats. However, recent studies have indicated that
marshes created by managed realignment are “significantly impaired” in their ability to deliver ecosystem services when compared with natural systems (Spencer and
Harvey, 2012) and do not meet the requirements of the
EU Habitats Directive (Mossman et al., 2012). Ecosystem
services valuation (Luisetti et al., 2011) concluded that
managed realignment can be economically efficient at
time frames longer than 25 years. However, results are
site-specific and should not be generalized, especially
when “complex social decisions” are involved (Luisetti
et al., 2011), such as in areas where people and assets are
at risk.
Managed realignment versus managed retreat
The focus of managed realignment projects oscillates
between improved flood risk management and environmental objectives, often with a bias toward habitat creation. Usually, medium- to long-term effects on flood risk
to inland areas are not clearly assessed, probably due to
uncertainties on the type of intertidal habitat that will
develop and how they will evolve through time. Where
saltmarshes fail to develop, coastal squeeze resumes as
sea level rises, posing a higher risk of flooding to people
and property. Conceptually, managed realignment has
great potential to (1) provide space for the creation of
intertidal habitats, (2) provide natural defense against
storms and rising sea levels, and (3) contribute to the
achievement of EU directives (i.e., floods, habitats, and
water framework). Esteves (2013) states that for this
potential to be realized, it is necessary that managed
realignment implementation (1) follows a long-term strategic plan that effectively integrates its multiple objectives
(e.g., habitat creation, flood protection, and amenity),
(2) has clearly defined local and national targets at known
time frames, (3) benefits from systematic monitoring so
performance can be adequately measured against targets,
and (4) is evaluated based on evidence so adjustments to
the strategy can be put in place where necessary.
In contrast with managed realignment, the main objective of managed retreat is the relocation of people and
assets at risk. Implementation of managed retreat might
include relocation of single structures at risk (e.g., the historic Cape Hatteras Lighthouse, USA) or a series of measures to reduce the number of people and property at risk
(e.g., the compulsory purchasing of property at high risk
adopted in France after the aftermath of the Xynthia storm
of 2010). Implementation of such schemes is complex due
to the range of public perception conflicts (e.g., Roca and
Villares, 2012), in addition to institutional capacity and
economic constraints. Managed retreat usually requires
strong integration between long-term planning and the
sustainability of risk reduction measures, which is often
deficient in public administrations. However, challenging
times require drastic changes and the only safe climateproof response at all temporal and spatial scales is to
reduce the number of people and assets at risk. As it is
an effective mechanism to reduce risk from both climatic
variability and extreme events, managed retreat has
increasingly been implemented (or planned) in many locations worldwide.
It is important to note that, so far, managed realignment
has been implemented only in rural areas. However, as
flood defenses are moved further inland, a long-term strategy is required to prevent risk to inland areas becoming
unacceptable. Managed retreat deals with development
in hazard-prone areas and, combined with long-term planning, may be applicable to a range of urban and industrial
areas. A more effective strategy to reduce the risk of
flooding to people and property would involve long-term
planning objectives with both managed realignment and
managed retreat implemented in predefined time frames.
Summary
Managed realignment is a soft engineering approach that
aims to create intertidal habitat (especially saltmarshes)
through the artificial breaching or removal of flood
defenses. The creation of intertidal habitats has two main
aims: (1) to offset the loss of designated intertidal habitat
(due to coastal squeeze and developmental pressures)
and (2) to dissipate wave energy to offer sustainable
coastal protection. Managed realignment is becoming
a popular coastal management approach in northern
Europe. As managed realignment is a relatively new
approach, there is a need to better understand the shortto long-term effects on (1) local sedimentary processes,
(2) inland flood risk and development of intertidal habitats
(and associated biota), (3) and wider socioeconomic and
environmental implications.
Bibliography
Beauchard, O., Jacobs, S., Cox, T. J. S., Maris, T., Vrebos, D.,
Van Braeckel, A., and Meire, P., 2011. A new technique for tidal
habitat restoration: evaluation of its hydrological potentials.
Ecological Engineering, 37, 1849–1858.
Esteves, L. S., 2013. Is managed realignment a sustainable longterm coastal management approach? Journal of Coastal
Research Special Issue, 65, 933–938.
Esteves, L. S., 2014. Managed realignment: a viable long-term
coastal management strategy? Ebrief in Environmental Sciences,
New York: Springer, 139p.
French, F. W., 1997. Coastal and Estuarine Management. London:
Routledge.
French, F. W., 2001. Coastal Defences: Processes, Problems and
Solutions. London: Routledge.
Friess, D. A., Spencer, T., Smith, G. M., Möller, I., Brooks, S. M.,
and Thomson, A. G., 2012. Remote sensing of geomorphological and ecological change in response to saltmarsh managed
392
MANAGED REALIGNMENT
of intertidal habitats as a primary objective. This approach
is partially driven by the need to address statutory duties
(e.g., the EU Habitats Directive) to take all necessary measures to avoid detrimental impact to designated conservation areas and provide compensation for loss of these
habitats. However, recent studies have indicated that
marshes created by managed realignment are “significantly impaired” in their ability to deliver ecosystem services when compared with natural systems (Spencer and
Harvey, 2012) and do not meet the requirements of the
EU Habitats Directive (Mossman et al., 2012). Ecosystem
services valuation (Luisetti et al., 2011) concluded that
managed realignment can be economically efficient at
time frames longer than 25 years. However, results are
site-specific and should not be generalized, especially
when “complex social decisions” are involved (Luisetti
et al., 2011), such as in areas where people and assets are
at risk.
Managed realignment versus managed retreat
The focus of managed realignment projects oscillates
between improved flood risk management and environmental objectives, often with a bias toward habitat creation. Usually, medium- to long-term effects on flood risk
to inland areas are not clearly assessed, probably due to
uncertainties on the type of intertidal habitat that will
develop and how they will evolve through time. Where
saltmarshes fail to develop, coastal squeeze resumes as
sea level rises, posing a higher risk of flooding to people
and property. Conceptually, managed realignment has
great potential to (1) provide space for the creation of
intertidal habitats, (2) provide natural defense against
storms and rising sea levels, and (3) contribute to the
achievement of EU directives (i.e., floods, habitats, and
water framework). Esteves (2013) states that for this
potential to be realized, it is necessary that managed
realignment implementation (1) follows a long-term strategic plan that effectively integrates its multiple objectives
(e.g., habitat creation, flood protection, and amenity),
(2) has clearly defined local and national targets at known
time frames, (3) benefits from systematic monitoring so
performance can be adequately measured against targets,
and (4) is evaluated based on evidence so adjustments to
the strategy can be put in place where necessary.
In contrast with managed realignment, the main objective of managed retreat is the relocation of people and
assets at risk. Implementation of managed retreat might
include relocation of single structures at risk (e.g., the historic Cape Hatteras Lighthouse, USA) or a series of measures to reduce the number of people and property at risk
(e.g., the compulsory purchasing of property at high risk
adopted in France after the aftermath of the Xynthia storm
of 2010). Implementation of such schemes is complex due
to the range of public perception conflicts (e.g., Roca and
Villares, 2012), in addition to institutional capacity and
economic constraints. Managed retreat usually requires
strong integration between long-term planning and the
sustainability of risk reduction measures, which is often
deficient in public administrations. However, challenging
times require drastic changes and the only safe climateproof response at all temporal and spatial scales is to
reduce the number of people and assets at risk. As it is
an effective mechanism to reduce risk from both climatic
variability and extreme events, managed retreat has
increasingly been implemented (or planned) in many locations worldwide.
It is important to note that, so far, managed realignment
has been implemented only in rural areas. However, as
flood defenses are moved further inland, a long-term strategy is required to prevent risk to inland areas becoming
unacceptable. Managed retreat deals with development
in hazard-prone areas and, combined with long-term planning, may be applicable to a range of urban and industrial
areas. A more effective strategy to reduce the risk of
flooding to people and property would involve long-term
planning objectives with both managed realignment and
managed retreat implemented in predefined time frames.
Summary
Managed realignment is a soft engineering approach that
aims to create intertidal habitat (especially saltmarshes)
through the artificial breaching or removal of flood
defenses. The creation of intertidal habitats has two main
aims: (1) to offset the loss of designated intertidal habitat
(due to coastal squeeze and developmental pressures)
and (2) to dissipate wave energy to offer sustainable
coastal protection. Managed realignment is becoming
a popular coastal management approach in northern
Europe. As managed realignment is a relatively new
approach, there is a need to better understand the shortto long-term effects on (1) local sedimentary processes,
(2) inland flood risk and development of intertidal habitats
(and associated biota), (3) and wider socioeconomic and
environmental implications.
Bibliography
Beauchard, O., Jacobs, S., Cox, T. J. S., Maris, T., Vrebos, D.,
Van Braeckel, A., and Meire, P., 2011. A new technique for tidal
habitat restoration: evaluation of its hydrological potentials.
Ecological Engineering, 37, 1849–1858.
Esteves, L. S., 2013. Is managed realignment a sustainable longterm coastal management approach? Journal of Coastal
Research Special Issue, 65, 933–938.
Esteves, L. S., 2014. Managed realignment: a viable long-term
coastal management strategy? Ebrief in Environmental Sciences,
New York: Springer, 139p.
French, F. W., 1997. Coastal and Estuarine Management. London:
Routledge.
French, F. W., 2001. Coastal Defences: Processes, Problems and
Solutions. London: Routledge.
Friess, D. A., Spencer, T., Smith, G. M., Möller, I., Brooks, S. M.,
and Thomson, A. G., 2012. Remote sensing of geomorphological and ecological change in response to saltmarsh managed
392
MANAGED REALIGNMENT