At Chimanimani, in Zimbabwe’s Eastern Highlands, we have just experienced the worst forest fire in this country’s history. On Sunday 20th September 1992 a fire started which burnt out, during four days, over 2,500 ha of land comprising 1300 ha of pine, wattle and eucalypts: add to this an area of Brachystegia (natural) woodland of ca. 800 ha and about half this area of natural/unimproved grazing land. Trees of all ages, mostly mature, were affected on two neighbouring properties.
The losses caused by the fires are estimated at Z$ 3 million with the cost of fire fighting put at Z$ 500,000. At one stage the fire front stretched for over 15 km and spotted up to 7 km from the primary fire. Prolonged dry conditions had generated a Keetch-Byram Drought Index figure of 735 which, incorporated into the locally computed Fire Danger Estimate of 71 produced a figure for that day of 79. Because of the extreme weather conditions, single digit humidity plus high winds and ambient temperatures, we think that this figure was low and should have been, maybe, 10 points higher: this variation suggests further refining of our forecast system may be needed. Fire fighters came in by air and road from as far away as Harare (400 km) and Mutare (150 km), adding to a ground fire-fighting force which peaked at 2000 people.
The behaviour of the fire puts into question the whole current concept of our fire protection measures; we may have to discard presently held theories for a few years until conditions become more manageable. The sacrificial back-burn was often the only effective way of containing the fire which was finally extinguished after two weeks, but only after the advent of more moderate, and moister weather. Many lessons were learnt which we hope will never need to be put into practice.
From: Frank Elias Chairman, Chimanimani Fire Protection Committee Address: P.O.Box 19 Chimanimani ZIMBABWE