PROJECT-AQUARIUS .4. EXPERIMENTAL BUSHFIRES, SUPPRESSION PROCEDURES, AND MEASUREMENTS

Experimental bushfires were lit over three summers in Australian eucal ypt forests with fuel loads (mean and range) of 11.3 (8-14) tonnes per hectare, in air temperature 25 (17-33)degrees C, relative humidity 47 (14-81)%, and wind speed 4.4 (2-9) m s(-1). The McArthur Forest Fire Danger Index (FFDI) ranged from 2 to 18 and was evenly distributed bet ween 'low', 'moderate', and 'high' fire dangers. Fires were lit on a c rosswind ignition line of 50-200 metres, and were allowed to develop f or 10-50 minutes before a seven-man hand-tool crew commenced its attac k. Airborne infra-red imagery showed that head-fire intensity (average d over 6 minutes) of most fires exceeded 1000 kW per metre of fire fro nt (kW m(-1)) at some stage and ranged as high as 3280 kW m(-1), chall enging the crew in much the same way as summer wildfires and evoking s imilar uncertainty and apprehension. Firefighters were generally unabl e to suppress headfires with an intensity of more than 1000 kW m(-1). Comprehensive measurements were made of the stresses the firefighters and scientific observers experienced, their physiological and subjecti ve responses, and the firefighters' productivity and efficiency. In al l, 23 km of fireline were constructed and 238 man-days of measurements were obtained - 179 on the firefighters, 59 on the scientists.