The impact zone: a surge of fire comparable to the opening of floodgates11th Feb 2019
The forecast warned that an extreme cold front was to hit the Western Cape that night. Emergency services were preparing for storm waters, but the prefrontal wind conditions that pushed ahead of the storm fanned smouldering embers and unleashed a surge of fire comparable to the opening of floodgates. There was simply no stopping this conflagration once it had reached a certain level of intensity.
The fires in Knysna and Plettenberg Bay during June 2017 are set to become a landmark incident in the history of wildfires in South Africa. To avoid experiencing similar disasters in the future, we need this incident to be transformative, with a positive outcome of real change and collaboration in the approach of how we view and manage wildfire risk reduction. Wildfires will continue to occur, but how we collectively approach dealing with this risk is very important.
While some suggest the recent fire is a one-in-a-hundred-year fire, it is quite clear (especially for those on the front line fighting fire) that we are witnessing a globally changing climate and the impact this will have on wildfire occurrence and fire behaviour severity is set to increase. It is therefore imperative that communities understand how to co-exist with wildfires, especially those that inhabit the Wildland Urban Interface (WUI). The WUI is the transitional zone where structures, homes and other human development meets the undeveloped or rural environment, also known as the wildland. The wildland is mostly a fire-driven ecosystem, which means it wants to burn.
If you live in an estate, the chances are you border on or live within the WUI. The advantage here is the serenity one feels when coming home to nature on one’s doorstep. However, that very same natural environment so many choose to live in can also become a risk when a wildfire is raging close by. The natural beauty we see around the homes and structures is fuel for fire, and unless it is Afromontane, it will burn. It must be noted that under certain conditions Afromontane forest will burn, but there is little known about the Afromontane fire regime (Midgley et al. 1997)
There is a way to co-exist with wildfire and remain in the WUI. Just like when one needs a particular approach to building within a floodplain, a similar approach must be applied to the WUI. The ideal community in the WUI is one where a wildfire literally flows past, inflicting little damage and allowing the inhabitants to move to a community safe zone then head back out to their homes once the fire has passed. This allows the fire services to concentrate on managing the ongoing fire rather than having their vehicles guarding homes.
In this scenario, a holistic approach to Integrated Fire Management (IFM) and the use of a system such as Check Protect Survive™ become so important. The latter is a detailed zone-by-zone analysis of risk to property from wildfire which advises on the required mitigation measures.
Defendable space’, ‘fuel reduction zone’ and ‘community safe zones’ are terms that may seem alien now but will soon hopefully become part of the everyday language of those inhabiting the WUI. The effect of not having good defendable space and fuel reduction zones around structures was highlighted during the Knysna fires. While the fire front impacted the homes that existed on the edge of the WUI, it was the storm raining fiery embers down into the landscape that caused so much of the damage. Embers landed in gardens, igniting the vegetation, and radiant heat shattered glass windows, allowing embers to spread. Embers also landed in gutters, igniting organic debris, and hose flames entered the roof space, causing homes to burn. These homes ignited other homes close by and so the fire storm spread, bringing the fire and destruction to those who had thought themselves safely away from the flaming front.
This incident highlights the importance of defendable space, which is the creation of space around a home or property that will result in a fire losing momentum and dropping in intensity. This allows firefighters the opportunity to safely take on the fire, or the homeowners themselves, having sheltered from the ember storm, can come out at the safest opportunity and extinguish the spot fires that would have started in the surrounding areas.
fuel- or firebreak is not enough to stop a wildfire. In fact, a fuel break is not meant to stop a wildfire – it is designed to slow a wildfire down in the right conditions and give access to fire crews to attempt suppression tactics.
In order to create defendable space, one needs to clear fine fuels from around one’s home, keep grass areas trimmed and watered, rake up and reduce leaf litter, remove flammable organic litter from around the house (especially gutters and roofs), and trim shrubs. There should be no shrubs over one metre high next to or below windows. Trim tree branches that overhang the house, and think about the ease with which fire might be able to spread from the ground into tree tops. Removing lower branches of trees and pruning shrubs so that their tops are well away from the lower branches of trees is advisable.
When designing a garden, use suitable plants with low flammability potential, and retain soil moisture in garden beds. Use the layout of the property to create open spaces to protect the property; these can be driveways, pools, tennis courts, gravelled areas, mown lawns, grazed paddocks and natural water features.
The landscape that is created around the property may very well determine its future.