Tom's Blog

Sunday, March 1, 2009

Computer modeling fire behavior with BehavePlus

One of the best talks I heard at the recent Wisconsin Prescribed Fire Council conference was by Ralph Sheffer, Fire Operations Specialist for the Wisconsin DNR. This was on BehavePlus, a versatile computer program that permits you to model fire behavior under numerous different scenarios. You can download this public domain software program free from

BehavePlus is a PC-based program that is a collection of models that describe fire behavior, fire effects, and the fire environment. It is a flexible system that produces tables, graphs, and simple diagrams and can be used for a multitude of fire management applications. You plug in your fuel type (grass, litter, etc.--there are dozens of options), your fuel moisture content, windspeeed, slope, relative humidity, etc. If you are interested in how windspeed affects the burn, you can plug in a series of different speeds. Once you have all the variables inserted, you Run the program and instantly the data are shown. You get both tabular and graphic results.You can then quickly change a parameter and rerun.

All the results can be exported and converted into an Excel file. The data below show the effect of windspeed on flame height and rate of flame movement. The flame speed data are given in chains/hour (this is a U.S. Forest Service program!), which I have converted (1 chain is 66 feet). The data in the table are for a relative humidity of 29%, and a slope of 0 (flat land).

One of the uses of BehavePlus is to develop burn plans for a particular burn unit. You can play with the variables and then decide when it would be advisable to burn. Great stuff, and very useful!

Wind speed Flame ht Flame speed
mi/h ft ft/min
0 1.6 2
1 3.1 9
2 4.4 18
3 5.5 29
4 6.5 42
5 7.3 55
6 8.2 69
7 8.9 84
8 9.7 100
9 10.4 117
10 11 134


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