Vulnerability of Ghana's coast to relative sea-level rise: A
scoping review Gulf of Guinea
S. Avornyo
Dept. of Marine and Fisheries Sciences, University of Ghana, Accra, Ghana
K. Appeaning Addo
Institute for Environment and Sanitation Studies, University of Ghana, Accra, Ghana
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering, University of Padova, Padova, Italy
P. Minderhoud
Gamma Remote Sensing, Gumligen, Switzerland
M. Woillez
Agence Française de Développement, France
ABSTRACT
Coastal areas are regions of
essential value that are home to
a myriad of services. However,
population growth and climate
change along with their
cascading impacts have had
profound impacts on their
topography and evolution.
Consequently, many coastal
regions, of which Ghana's coast
is no exception, are incessantly
plagued with hazards that are
increasing in both magnitude
and frequency. Predominantly
through the recurrence of floods
and erosion, Ghana's coast is
increasingly becoming
susceptible, with huge socio-economic implications
considering its environment-dependent economy. Several
previous attempts have been
made to assess Ghana's coastal
vulnerability to comprehend the
complexities underpinning the
occurrence of these hazards.
Most studies blame global sea-level rise, but coastal land
subsidence could also have
significant impacts. Indeed, land
subsidence is a major
component of relative sea-level
rise in many coastal cities
worldwide. Drawing on extant
literature in Ghana, this scoping
study provides an overview of
three crucial and interrelated
dimensions: sea-level rise,
subsidence and coastal
vulnerability. We also identify
crucial knowledge gaps which
impede comprehensive risk
assessment of Ghana's coast.
The survey findings indicate a
significant understudy of these
issues albeit posing potential
threats to Ghana’s coast. It
brought to light the absence of a
ground-validated subsidence
study; a non-identification of
potential local subsidence
drivers; a non-availability of a
subsidence-infused coastal
vulnerability assessment; non-existing studies on combined
effects of climate change and
subsidence; and huge deficits in
available data for numerical
modelling of coastal subsidence.
A case study of the Volta delta
using the PS-InSAR technique
and Global Positioning System
(GPS) surveys is also provided. It
establishes the occurrence of
subsidence. Interferograms of
Sentinel-1 data from 2016 to 2020
indicated deformation rates
ranging from -9.16 mm/yr to 1.77
mm/yr, with a majority of
persistent scatterers (99.81%)
showing land subsidence.
Guided by the identified
knowledge and data gaps and
the need to mitigate impacts,
the study recommends a
thorough assessment of relative
sea-level rise and coastal
vulnerability; a continuous and
long-term monitoring framework
for drivers of change; a review of
coastal management strategies;
and the establishment of
continuous GPS stations, tidal
stations, elevation benchmarks.
