Strong bergwind conditions coupled with very dry vegetation most probably resulted in the flare-up of a lightning-induced smouldering fire on the morning of 7 June 2017 in the Elandskraal region, northwest of Knysna, resulting in one of the worst fire disasters in South Africa’s history.

This is according to a scientific report which the Council for Scientific and Industrial Research (CSIR) recently concluded. The report provides a scientific assessment of the most likely sequence of events that led to the Elandskraal fire in the Western Cape in June 2017.

Although there were two distinct fires in the Knysna area – in Elandskraal and Kruisfontein - which both started on 7 June 2017, the CSIR report only focuses on the Elandskraal fire, as the cause of the Kruisfontein fire was well-documented.

“The cause, location and timing of the ignition of the Elandskraal fire was a contentious issue from the outset as limited data were available at the time. However, due to the activation of the International Charter on Space and Major Disasters, space agencies (e.g. NASA and ESA) and commercial satellite image providers directed the acquisition of satellite imagery to the disaster zone and more satellite data became available. This presented a gold mine of data to the CSIR researchers who could piece together a probable sequence of events. The analyses provide valuable insight into the conditions that led to this disastrous fire and thus may assist in mitigating fire risks and inform responses in future,” says Philip Frost, CSIR research group leader.

Following reviews by local and international experts, the scientific report was submitted to fire managers, relevant stakeholders, such as the Southern Cape Fire Protection Association, the Western Cape’s Provincial Disaster Management Centre, Knysna municipality, International Charter on Space and Major Disasters and is now available to the general public.

The CSIR used all available geospatial data to better understand how, where and when this fire started and analysed its spread during the first 45 minutes. This includes the use of images from various satellite, drone video footage, lightning and weather data.

The report’s findings can be summarised as follows: 

• Extensive corroborating scientific evidence points to the existence and spread of a smouldering fire (probably underground) that was most likely caused by a lightning strike that occurred on 22 March 2017 in the area of Elandskraal.

• The first sign of evidence of the existence of a patch of brown, dying vegetation was detected by the Sentinel 2 satellite on 29 March 2017. Satellite imagery indicates that the area of smouldering vegetation had grown to 3 033 square metres by 18 May 2017, prior to the Elandskraal fire. The patch of dying vegetation is now also visible in satellite images on Google Earth. 
• Lightning strike data from the South African Weather Service’s South African Lightning Detection Network suggests that a positive lightning strike that occurred on 22 March 2017, in the Elandskraal area, was the most likely cause of the smouldering patch of vegetation (referred to as a “holdover” fire), but this cannot be established for certain.
• On the morning of 7 June 2017, north-westerly winds had reached maximum speeds of up to 50 km/h by 03:30 and 55 km/h at 05:23. This could have provided sufficient oxygen for a smouldering, underground fire to flare up.
• Based on active fire detection by satellites, it is estimated that the smouldering patch of vegetation most likely flared up between 05:00 and 05:30 on 7 June 2017.

CSIR researchers compiled the report with the assistance of the Advanced Fire Information System (AFIS), a technology developed by the CSIR over the past 13 years to assist in the prediction, detection and assessment of wildfires globally.

Frost says that the AFIS technology is critical to various stakeholders in the fire and disaster management sector.

Fire risk along the wildland-urban interface (WUI) of the fynbos biome can be calculated and mapped using a geospatial assessment procedure previously demonstrated by the CSIR.

The report further recommends that the risk assessment procedure be expanded to the entire fynbos biome and augmented by including data of vegetation/fuel type, fuel load (biomass), fuel moisture and burn history (time since last burn), all of which can already be derived from satellite imagery on an ongoing basis. Such a system will assist government and land owners to understand fire risks along the WUI and help avoid or mitigate fire disasters in future. 

The full report can be found on https://www.csir.co.za/documents/csir-knysna-report-2018pdf

Ends

Issued by David Mandaha, CSIR Media Manager, 012 841 3654.

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