The risks, management and adaptation to sea level rise and coastal erosion along the Southern and Eastern African Coastline.
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Date
2012
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Abstract
Sea level rise and coastal erosion are two processes which may result in
major problems for coastal cities around the world. This is particularly
true for Southern and Eastern African cities as they struggle to meet
their developmental challenges in addition to sea level rise and coastal
erosion. This thesis focuses on three main areas, the analysis of the rates
of sea level from tide gauges in the region, the extent of wave run-up on
the beach and the development of a simple technical and management
framework that managers can apply to assess coastal hazards.
The rates of sea level rise in the region vary, Zanzibar, Tanzania reflects a falling sea level at -3:64 plus minus 1:62 mm per year while the highest
rate of sea level rise at Diego Garcia, British Indian Ocean Territories
is +4:35 plus minus 7:61 mm per year. The rate of sea level rise are dependent
on the complex interactions of vertical crustal movements, barometric
pressure changes, and the warm Agulhas and cooler Benguela currents.
Wave run-up is an indicator of the hazard zone. A number of international
wave run-up models were assessed for use in this region and were
found to be unsuitable. A new wave run-up model was developed which
uses the bathymetric profile as opposed to the beach slope in predicting
wave run-up. This model uses the equation Rx H0 = C S2=3, where Rx is the
wave run-up height above Still Water Level, H0 is the significant wave
height at the closure depth, C is dimensionless coefficient where median
values are described by C ' 7:5, S is a representative nearshore slope
(S = (hc=xh)). hc is the closure depth and xh the horizontal distance
from the waters edge to the closure depth.
An assessment of the impacts of sea level rise and wave run-up was undertaken
based on a detailed case study of the Durban coastline. The
results were incorporated into a standalone freeware viewer tool enabling
this information to be accessible to planners, decision makers and the
general public. The research has identifed several types of shoreline that
are vulnerable to coastal erosion, sea level rise and extreme wave events.
Recommendations as to what adaptation measures could be undertaken
for the different beach types are proposed. With this information coastal
managers and decision makers charged with managing shorelines can
take the first step in understanding and adapting into the future.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.
Keywords
Sea levels., Coast changes., Theses--Environmental science.