Coastal Vulnerability Index

Vulnerability relates to one’s predisposition to be affected, or to be susceptible to damage. The CVI assesses the relative physical coastal vulnerability based on a set of coastal parameters which serve as indicators of vulnerability.

This assessment also tries to address social, economic and ecological factors by identifying indicators and assessing them in relation to the findings of the CVI to determine which populations and associated infrastructure are potentially at risk.

Need for this Coastal Vulnerability Assessment

Coastal regions around the world are increasingly becoming vulnerable to the effects of coastal erosion, extreme coastal storms and sea-level rise.

The March 2007 storm event in KZN resulted in significant damage to properties and infrastructure costing millions of rands.
Climate change predictions are that the east coast of South Africa will be subjected to increased frequency and intensity of storms.

Aim of this Assessment

Which sections of coast are at the highest physical vulnerability to future events of this nature?

What social, economic and ecological features are potentially vulnerable?

Interpretation of the CVI

RISK

Lowest risk category – likelihood of impact or damage is lower. Physical parameters are in good condition. If developments in these areas are approved they may increase the vulnerability of these areas. New developments should be set-back appropriately so as to maintain the natural functioning of the coast.

MODERATE RISK

Sites are at higher risk than areas of Risk, but lower than areas of High Risk. Likelihood of sites being damaged is higher. Retreat and defence should be explored for existing infrastructure. New developments should be set-back sufficiently or alternative sites should be considered.

HIGH RISK

These sites are considered to be the most susceptible to the effects of erosion, sea-level rise or extreme events. Existing developments have a High likelihood of being damaged. It is recommended that the options of retreat and defence be explored. New developments should be set-back sufficiently to ensure that they are not damaged. Alternatively, new sites for the development should be considered.

Physical CVI

Physical Parameter	Extremely Low (1)	Low (2)	Moderate (3)	High (4)
Beach width	> 150m	100 – 150m	50 – 100m	< 50m
Dune width	> 150m	50 – 150m	25 – 50m	< 25m
Distance to the 20m isobath	> 4km	2 – 4km	1 – 2km	< 1km
Distance of veg behind back beach	> 600m	200 – 600m	100 – 200m	< 100m
Percentage outcrop	> 50%	20 – 50%	10 – 20%	< 10%

Social, Economic and Ecological Components

The primary concern relates to the 23% of coast classified as High Risk.
The CVI identified indicator features of social, economic & ecological importance.
It assessed where features are in relation to cells of High Risk.
Features located in or across the littoral active zone are at relatively higher risk if all, or a proportion, fall directly within a cell of High Risk.

Social, Economic and Ecological Components

Economic & commercial activities	Strategic infrastructure	Recreational areas	Subsistence sites	Ecological important areas	Residential properties
Dune Mining	Piers	Boat launch sites	Subsistence fishing site	Marine protected areas	Residential erven
Forest plantation	Roads	Fishing hot spots	Subsistence harvesting sites	Bird Sanctuary sites
Sugar cane	Railway lines	Swimming beaches	Subsistence farming areas	Turtle nesting sites
Commercial & industrial buildings	Lighthouses	Sports facilities		Estuary mouth
Commercial farms		Coastal public property		Protected areas (terrestrial)