globals [ initial-grass ;; how many grass (green patches) we started with burned-grass ;; how many have burned so far wind-deg ;; wind heading in degrees wind-x ;; x location of next patch based on wind wind-y ;; y location of next patch based on wind humidity-numb ;; percent humidity that corresponds to user choice burn-time ;; length of time fire has been burning ] breed [fires fire] ;; bright red turtles -- the leading edge of the fire breed [embers ember] ;; turtles gradually fading from red to near black breed [winds wind] ;; wind indicator arrow ;; ;; Set all variables, wind, arrows, and fire ignition area ;; to setup clear-all set-default-shape turtles "square" ;; find which direction wind is blowing from user Wind-Blow ;; set arrow to indicate wind create-winds 1 [ setxy (min-pxcor + 25) (min-pycor + 25) set shape "arrow" set size 15 set color yellow set heading wind-deg ] ;; assign value to user-chosen humidity level Humidity-Level ;; make some grass ask patches with [(random-float 100) < Density] [ set pcolor green ] ;; ignition point for wildfire, need spec. of lightning strike ask patches with [pxcor ^ 2 + pycor ^ 2 < 5] ;; thank you Dale. "The last number is the radius" [ ignite ] ;; set grass counts set initial-grass count patches with [pcolor = green] set burned-grass 0.0 ;; reset fire burn time set burn-time 0.00 end ;; ;; Based on the user's choice of wind direction, set the wind-deg, wind-x, and wind-y to the correct numbers ;; to Wind-Blow if Wind-heading = "N" [ set wind-deg 0 set wind-x 0.0 set wind-y 1.4 ] if Wind-heading = "NE" [ set wind-deg 45 set wind-x 1.0 set wind-y 1.0 ] if Wind-heading = "E" [ set wind-deg 90 set wind-x 1.4 set wind-y 0.0 ] if Wind-heading = "SE" [ set wind-deg 135 set wind-x 1.0 set wind-y -1.0 ] if Wind-heading = "S" [ set wind-deg 180 set wind-x 0.0 set wind-y -1.4 ] if Wind-heading = "SW" [ set wind-deg 225 set wind-x -1.0 set wind-y -1.0 ] if Wind-heading = "W" [ set wind-deg 270 set wind-x -1.4 set wind-y 0.0 ] if Wind-heading = "NW" [ set wind-deg 315 set wind-x -1.0 set wind-y 1.0 ] end ;; ;; Based on the user's choice of humidity level, set the humidity-numb to the percent humidity ;; to Humidity-Level if Humidity = "Low" [ set humidity-numb 20 ] if Humidity = "Medium" [ set humidity-numb 40 ] if Humidity = "High" [ set humidity-numb 60 ] end ;; ;; Main procedure ;; to go ;; if no fires or embers, stop the spread of fires if not any? turtles [ stop ] ;; adjust how often the fire spreads, based on the humidity if ((Ticks mod (humidity-numb ^ 2 / 100)) = 0) [ ask fires [ ;; every 3rd tick, spread in 4 directions instead of along the wind direction ifelse ((Ticks mod 3) = 0) [ ask neighbors4 with [pcolor = green] [ ignite ] ] ;; move along the wind direction for ticks 1 and 2 [ let target patch-at wind-x wind-y if target != nobody [ ask target [ if pcolor = green [ ignite ] ] ] ] ;; every 3rd tick, fires become embers if ((Ticks mod 3) = 0) [ set breed embers ] ] fade-embers ] ;; track how long the fire has been burning, two ticks is 1 second set burn-time burn-time + (1.00 / 120) if ((Ticks mod 2) = 0) [ ;; update the graph UpdateGraph ] tick end ;; ;; creates the fire turtles by sprouting new fire, setting patch color, and adding 1 to burned-grass ;; patch procedure ;; to ignite sprout-fires 1 [ set color red ] set pcolor black set burned-grass burned-grass + 1.0 end ;; ;; achieve fading color effect for the fire as it burns, rate of fading is relative to humidity ;; to fade-embers ask embers [ ;; make red darker until we are almost at black set color color - ((100 - humidity-numb) / 100) if color < red - 3.5 [ set pcolor color die ] ] end ;; ;; Update the graph ;; to UpdateGraph set-current-plot "Rate of Burn" set-current-plot-pen "Veg. Area" plot count patches with [pcolor = green] set-current-plot-pen "Burn Area" plot burned-grass end ;; ;;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ;; ;; Modified 7/28/2009, Rachel Robinson, Jocelyn Comstock, Kenny ;; ;;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ; *** NetLogo 4.0.4 Model Copyright Notice *** ; ; This model was created as part of the project: CONNECTED MATHEMATICS: ; MAKING SENSE OF COMPLEX PHENOMENA THROUGH BUILDING OBJECT-BASED PARALLEL ; MODELS (OBPML). The project gratefully acknowledges the support of the ; National Science Foundation (Applications of Advanced Technologies ; Program) -- grant numbers RED #9552950 and REC #9632612. ; ; Copyright 1997 by Uri Wilensky. All rights reserved. ; ; Permission to use, modify or redistribute this model is hereby granted, ; provided that both of the following requirements are followed: ; a) this copyright notice is included. ; b) this model will not be redistributed for profit without permission ; from Uri Wilensky. ; Contact Uri Wilensky for appropriate licenses for redistribution for ; profit. ; ; This model was converted to NetLogo as part of the projects: ; PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING ; IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. ; The project gratefully acknowledges the support of the ; National Science Foundation (REPP & ROLE programs) -- ; grant numbers REC #9814682 and REC-0126227. ; Converted from StarLogoT to NetLogo, 2001. ; ; To refer to this model in academic publications, please use: ; Wilensky, U. (1997). NetLogo Fire model. ; http://ccl.northwestern.edu/netlogo/models/Fire. ; Center for Connected Learning and Computer-Based Modeling, ; Northwestern University, Evanston, IL. ; ; In other publications, please use: ; Copyright 1997 Uri Wilensky. All rights reserved. ; See http://ccl.northwestern.edu/netlogo/models/Fire ; for terms of use. ; ; *** End of NetLogo 4.0.4 Model Copyright Notice *** @#$#@#$#@ GRAPHICS-WINDOW 199 10 631 463 105 105 2.0 1 10 1 1 1 0 0 0 1 -105 105 -105 105 1 1 1 ticks CC-WINDOW 5 711 750 806 Command Center 0 BUTTON 656 81 725 117 go go T 1 T OBSERVER NIL NIL NIL NIL BUTTON 59 139 129 175 setup setup NIL 1 T OBSERVER NIL NIL NIL NIL CHOOSER 25 41 163 86 Wind-Heading Wind-Heading "N" "NE" "E" "SE" "S" "SW" "W" "NW" 6 SLIDER 4 4 176 37 Density Density 0 100 80 1 1 NIL HORIZONTAL MONITOR 643 127 741 172 Percent Burned ( burned-grass / initial-grass ) * 100 1 1 11 CHOOSER 26 90 164 135 Humidity Humidity "Low" "Medium" "High" 2 MONITOR 643 176 740 221 Time in Minutes burn-time 2 1 11 PLOT 199 469 632 697 Rate of Burn NIL NIL 0.0 10.0 0.0 10.0 true true PENS "Veg. Area" 1.0 0 -10899396 true "Burn Area" 1.0 0 -16777216 true @#$#@#$#@ WHAT IS IT? ----------- This project simulates the spread of a fire running through a field that has been started by a lightning strike at a particular location. It shows that the time it takes and the percent of land burned by the fire are a function of the density of grasses present (in this case - Lovegrasses), humidity at the time of the strike and wind direction but not it's magnitude. HOW IT WORKS ------------ The fire starts at the center of the field and spreads in the direction of prevailing wind selected (standard cardinal and intermediate directions). Our model assumes that the wind is constant in the direction chosen and that the fire spreads in this direction. It also assumes that there is grass present that can be burned and that if they have already been burned they cannot be burned again. Our model also makes generalized assumptions regarding humidity level. We have programed it to represent three levels of humidity: high, medium and low. It allows for various rates of spreading based on the amount of humidity present at time of strike. HOW TO USE IT ------------- Select your desired density (% of grass coverage) slider, Wind direction (standrad cardinal and intermediate directions) and Humidity level (high, medium or low). (Note: Changes in the Density slider, Wind direction pulldown and Humidity level pulldown do not take effect until the next SETUP.) Click the SETUP button to set up the grass (green), fire (red at the center of view) and an arrow to indicate wind direction. Click the GO button to start the simulation. The DENSITY slider controls the density of grass in the field. The HUMIDITY chooser controls whether the humidity is high (low burn response), medium (higher burn response) or low (high burn response). THINGS TO NOTICE ---------------- When you run the model, how much of the grass burns? If you run it again with the same settings, does the same amount of grass burn? How similar is the burn from run to run? The density of the grass during the runs should also have an effect on the way the wildfire progresses or not, how does that density therefore effect the time it takes to burn the field. Some other things to consider is how does the amount of humidity effect the burning process, slower or faster? Does the cardinal direction chosen effect how fast the field is burned within the various humidity settings? Each turtle that represents a piece of the fire is born and then dies without ever moving. What each turtle does is looks at its neighbor, determines whether or not it is "ready" to be burned, if it is ready to be burned then a new turtle is born and runs through the same process. (We have called this "generational transfer" and it explains why if the fire is made of turtles but no turtles are moving that the fire appears to move). THINGS TO TRY ------------- Set the density of grass at various levels to determine how much is needed to have a complete burn. If the grass is not a consistant cover will the fire spread or die out? Set the humidity at various levels to determine what effect it has on the grassland itself but ultimately the start of fires due to lightning, fry or otherwise. Set the wind direction to one of the standard cardinal and intermediate directions to see if this effects how longs it takes to burn the entire field. Try setting up and running a BehaviorSpace experiment (see Tools menu) to analyze the percent burned at different grass density levels and different humidity livels. EXTENDING THE MODEL ------------------- Change the wind to include magnitude (speed at which it travels)from the various directions to increase the rate at which the field is burned through. The addition of topography to illustrate how land variances effects the overall change in burning would also be of interest. NETLOGO FEATURES ----------------- Unburned grass is represented by green patches; burning grass and wind direction are represented by turtles. Three breeds of turtles are used, "fires", "embers" and "winds". When the grass catches fire, a new fire turtle is created; a fire turns into an ember every three ticks (turns). Notice how the program gradually darkens the color of embers to achieve the visual effect of burning out. The wind drives the fire in the direction selected. Humidity levels effect the number of ticks between each new fire generation starting to "die" and inversely effect the rate at which embers darken. The wind direction sets a related degrees within a unit circle and is used to determine the general direction of fire spread. The "neighbors4" primitive is used to spread the fire in a more natural configuration every third generation. You could also write the model without turtles by just having the patches spread the fire, and doing it that way makes the code a little simpler. Written that way, the model would run much slower, since all of the patches would always be active. By using turtles, it's much easier to restrict the model's activity to just the area around the leading edge of the fire. RELATED MODELS -------------- Fire, Percolation, Rumor Mill CREDITS AND REFERENCES ---------------------- Portions of the code for this model were taken from the Fires model in the Netlogo Models Library under Earth Science copyrighted: Wilensky, U. (1997). Netlogo Fire Model. http://ccl.northwest.edu/netlogo/models/Fire. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL. **bibliography info: To refer to this model in academic publications, please use: Wilensky, U. (1997). NetLogo Fire model. http://ccl.northwestern.edu/netlogo/models/Fire. 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