Little research has been conducted with respect to water requirements for wildfire suppression. An exploratory and robust regression analysis was conducted on statistical material extracted from a Swedish database, focusing on data related to the fire suppression. The variables included are the amount of water applied, application rate of water, extinguishing time, flame height, and the total fire area. The results of the analysis with potential relationships are described, discussed, and compared with results from earlier research. After initial outlier detection, a robust regression analysis was performed and relationships developed. It was found that the developed relationships could predict the dependent variable very well; this was especially the case with the extinguishing time as a function of the total fire area. The relationship with the lowest ability to predict the dependent variable was the application rate of water as a function of the total fire area. The large number of parameters and their included uncertainties could be an explanation to the increased inability to predict the dependent variable. When comparing the control times of earlier conducted building fire studies with the extinguishing times of developed relationships, it was found that the control times were much longer than the corresponding extinguishing times. The reason behind was most likely due to the difference in the fire area applied in the equations. The resulting relationships for the grass fuel type were found to have lower ability to predict the dependent variable. The reason behind this is unclear and needs to be investigated further.
Extinguishing time, robust regression analysis, water application, wildfire suppression
 Stechishen E., Measurement of the Effectiveness of Water as a Fire Suppressant, Forest Fire Research Institute Information report FF-X-23, Ottawa, 1970.
 Stechishen E. & Little E.C., Water Application Depths Required For Extinguishment of Low Intensity Fires in Forest Fuels, Forest Fire Research Institute Information report FF-X-29, Ottawa, 1971.
 Loane I.T. & Gould J.S., Project Aquarius, Aerial Suppression of Bushfires, National Bushfire Research Unit, CSIRO Division of Forest Research, Canberra, 1986.
 Douglas D.R., Initial Attack Standards, Research working group no 6, Newsletter no 4, July 1973.
 Andrews P.L. & Rothermel R.C., Charts for Interpreting Wildland Fire Behaviour Characteristics, USDA Forest Service, Intermountain Forest and Range Experiment Station General Technical Report INT-131, Ogden, 1982.
 Alexander M.E., Fire Behaviour as a Factor in Forest and Rural Fire Suppression, New Zealand Fire Service Commission & The National Rural Fire Authority Forest research bulletin no 197 Forest and rural fire scientific and technical series report no 5, Wellington, 2000.
 Hansen R, Estimating the amount of water required to extinguish wildfires under different conditions and in various fuel types. International Journal of Wildland Fire, 21, 525–536, 2012. doi: http://dx.doi.org/10.1071/wf11022
 Thomas P.H., A Note on the Extinguishment of Very Large Fires, Fire Research Note 245, Borehamwood, England, 1957.
 Baldwin R., The Use of water in the Extinguishment of Fires by Brigades, Fire Research Note 803, Borehamwood, England, 1970.
 Lundqvist M., Electronic correspondence with Marie Lundqvist, MSB, Sweden 2011-12-21, 2011.
 Malmqvist M., Electronic correspondence with Mikael Malmqvist, MSB, Sweden 2012-06-29, 2012.
 Mosteller F. & Tukey J., Data Analysis and Regression, a Second Course in Statistics, Pearson, 1977.
 Elliott A.C. & Woodward W.A., Statistical Analysis Quick Reference Guidebook, Sage Publications Inc.: Thousand Oaks, 2007.