Reaction to flood warning.

Symposium Dates 26-29 May 1976

A moderate flood occurred in the lower Logan River in south-east Queensland in February 1976. Flood forecasts were prepared by one of the authors and disseminated to residents likely to be affected by Beaudesert Shire Council. Deficiencies in the forecasting method resulted in an overprediction of the flood peak by 2.5m, and also a prediction that the peak would occur 11 - 17 hours before the actual peak. Warnings and evacuations were based on the flood forecasts. Interviews were conducted by the second author immediately after the flood to determine the response to the flood warnings and preferences for method of and agency responsible for flood warnings to the public. The effect of the forecasting errors on likely attitudes to future flood forecasts was also explored. It was noted during the progress of the investigation that, following a flood, persons affected by the flood rationalise their behaviour prior to and during the flood. This process occurs quite soon after the flood, and an important implication is that post-flood surveys of social factors should be carried out before the clean-up is completed. Similar behaviour has been noted following other floods in the Brisbane area