Risk classification of veldfires as a basis for

prioritising the establishment of FPAs

What does the Act require?

The Act requires a consistent basis for the setting of priorities for veldfire management interventions.

Setting priorities requires an assessment of the risk of veldfire in various localities.

Rationale (1)

Veldfire risk is the chance of a veldfire igniting, spreading and causing damage to one or more assets, measured in terms of likelihood and consequence.

The risk classification used is therefore based on:– the likelihood of the natural vegetation

burning– the consequence should a fire occur.

Rationale (2)

The risk classification so derived is then assigned to each municipality.

But first, the fire types occurring within each municipality have to be determined.

Determining the fire type (1)

Start at the biome level. Vegetation within the biomes come from

the work of Low and Rebelo (1996) (see next slide).

For example, vegetation types in the Fynbos Biome are:(West Coast Renosterveld, North-Western Mountain Renosterveld, Central Mountain Renosterveld, Grassy Fynbos, South & South-Eastern Coast Renosterveld, Escarpment Mountain Renosterveld, Laterite Fynbos, Sand Plain Fynbos, Limestone Fynbos and Mountain Fynbos)

Vegetation of South Africa, Lesotho and Swaziland:

Low and Rebelo (1996)Department of Environmental Affairs and Tourism,

Pretoria

Determining fire types (2) For all vegetation types a fire type

is assigned. A fire type is a set of vegetation

types having a similar frequency and nature of veldfire. (This is determined from available literature)

– e.g. Fynbos Fire Types: (Laterite Fynbos, Sand Plain Fynbos, Limestone Fynbos and Mountain Fynbos)

Veldfire risk is accessed for each fire type using standard risk assessment techniques

Likelihood of a veldfire occurring

(adapted from Standards Australia, 1999). Likelihood

rating:Likelihood: indicative frequency

Description

Almost certain 1 in 2 years Is expected to occur

Likely 1 in 5 years Will probably occur

Possible 1 in 10 years Might occur at some time

Unlikely 1 in 20 years Could occur at some time

Rare 1 in 100 years May only occur in exceptional circumstances

Level Social Economic Environmental Catastrophic Death. Negative impact for large

part of the community or region. Long-term outside resources needed for recovery.

Permanent loss of species or habitats.

Major Extensive injury and evacuation.

Serious financial loss. Outside assistance needed.

Temporary loss of species and habitat destruction needed several years to recover.

Moderate Medical treatment needed.

Localised damage to property. Short-term external assistance needed.

Serious impacts needing a few years to recover.

Minor First aid at scene. Slight damage to assets. No external help needed.

Environmental assets recover rapidly.

Insignificant No injuries. No damage to property. Minor temporary impact

Consequences in terms of social, economic and

environmental impacts

Likelihood Rating

Consequence Rating

Insignificant Minor Moderate Major Catastrophic Extreme (almost certain)

Moderate Moderate High Extreme Extreme

High (likely) Low Moderate High Extreme Extreme Moderate (possible) Low Moderate High High Extreme Low (unlikely) Low Low Moderate High High

Risk levels in terms of likelihood and consequences

Risk level Action needed Extreme Priority areas for risk reduction measures High Risk reduction measures by all relevant

agencies Moderate Routine precautions to be undertaken by

landowners Low No action required as veldfire is unlikely and

consequences are negligible

Actions to take depending on the level of risk

Risk assessment and assessed risk levels in each fire type in South Africa.

Fire type Likelihood of critical veldfire scenario

Consequence of critical veldfire scenario

Veldfire risk level

Forest Rare Moderate Low

Thicket Rare Moderate Low

Arid Woodland Possible Major High

Moist Woodland Likely Catastrophic Extreme

Sparse Arid Woodland Rare Minor Low

Succulent Karoo Rare Minor Low

Nama Karoo Unlikely Minor Low

Grassy Nama Karoo Possible Minor Medium

Coastal Grassland Likely Minor Medium

Sour Grassland Almost Certain Catastrophic Extreme

Sweet Grassland Likely Moderate High

Fynbos Possible Moderate High

Renosterveld Unlikely Moderate Medium

Risk classification method (at municipal level)

Assume a critical fire scenario for each fire type.

Judge consequences of the scenario.

Assess the likelihood of the scenario.

(Above from existing reports)

Classify risk accordingly.

Assign fire risk to each municipality

Determine extent of fire type within municipality (Overlay municipality boundaries with Low and Rebelo map which is based on untransformed vegetation)

>30% of area with highest fire risk determines fire type for that area

The risk level is determined by the dominant fire type

Risk level is downgraded if higher risk types are found in areas where they are not a hazard to assets (e.g. Fynbos in isolated mountains)

Qualitative explanation of risk classifications

Moist woodland and sour grassland both rated as extreme

Fynbos rated as high

Assessed veldfire risk levels in some of the municipalities of the Western Cape, in each fire danger region.

Fire danger regionMunicipality

codeName of

municipalityMajor town

Veldfire risk level

Critical fire type

Bokkeveld WC022 Witzenberg Ceres H Fynbos

WCDMA01 WCDMA01 (Cedarberg)

Citrusdal H Fynbos

Breede River WC025 Breede Valley Worcester M Fynbos (patchy)

WC026 Breede River/Winelands

Montagu M Renosterveld

Cape Agulhas to Mossel Bay

WC042 Langeberg Riversdale H Fynbos

WCDMA03 WCDMA03 (De Hoop Nature

Reserve)

Bredasdorp H Fynbos

Cape Hangklip to Cape Agulhas

WC031 Theewaterskloof Caledon M Renosterveld

WC032 Overstrand Hermanus H Fynbos

WC033 Cape Agulhas Bredasdorp M Renosterveld

WC034 Swellendam Swellendam M Renosterveld

SA Municipalities classified by veldfire risk

Conclusion:

This veldfire risk assessment provides a basis for prioritising FPAs, and assigning resources accordingly.

Those areas with the highest fire risk get the first FPAs.

An example at a finer scale

This approach can be used at finer scales e.g. Cape Peninsula National Park

However, a comprehensive spatial database of the hazards and the social, environmental and economic assets is needed

Veldfire likelihood map(Courtesy of the Cape Peninsula National Park)

Veldfire consequence map (Courtesy of the Cape Peninsula National Park)

Veldfire risk map (Courtesy of the Cape Peninsula National Park)