Farm Irrigation

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WHAT IS IT?

This model simulates a farm during the life cycle of a crop. The user acts like a farmer who chooses how to grow the crop. The user selects the type of crop, soil and irrigation method. The frequency and amount of crop irrigation is chosen so as to maximize the crop yield and make the most efficient use of water. The model runs for the life cycle of the crop. Each plant absorbs and uses the water from the soil. Water is also lost through evaporation and drains into the earth. Crops can die from an excess or lack of water. This model lets the user adjust the parameters in order to see what optimizes their objective.

HOW IT WORKS

Plants absorb water from the soil. The user irrigates the farm periodically. Soil patches diffuse 10% of their water content to their neighbors at every tick. Soil loses some amount of water directly to the atmosphere via evaporation. More water is lost down to the earth due to drainage. This depends on the type of soil chosen: sand, clay or loam. If the soil has too much or too little water then the plant on that patch of soil dies. Individual plants are not identical. Plants of the same crop have slightly differing optimium water content values that very by about 10% between each other. This adds a level of heterogeneity in the crop. This is more realistic as no two peppers are exactly the same. Based on the parameter values irrigation water is applied to the field every period number of ticks. The color of the patches indicates how much water is present. Dark brown means lots of water, light brown means less water. When the crop starts dying one by one plants die and disappear from the model.

HOW TO USE IT

Using the respective sliders set the number of plants, evaporation rate, period and irrigation-amount-per-patch. Period is the number of ticks in between two successive irrigation actions. If periodic is turned on then irrigaion will continue automatically once every period. If not on then irrigation will be one time. Using the respective choosers choose the crop to be grown, the irrigation method to be used, the kind of soil and the arrangement of the crops on the field. Then hit setup to initialize the model and then hit go. The model will stop once all turtles are dead or the lifecycle of the crop is over.

The irrigation efficiency is shown in a plot. The number of plants killed from an excess and lack of water are monitored too. The average water content of the plants and the average patch water content is monitored in the top two plots. The crop yield, which is the percentage of initial crops that are still alive, is shown in a monitor window as well. The number of plants is also plotted as a function of time.

THINGS TO NOTICE

There are 5 output plots. Notice how the average patch water content zig-zags up and down, but usually have a net rise or fall over the lifespan of the model. The efficiency plot measurs the percentage of water irrigated that is used by the plants. The plot usually tends to follow a shifted logarithmic curve. When running the model sometimes you will see that initially a lot of plants die but then the model reaches a somewhat steady number and the population tends to plateau till the end. However in some cases the population suddenly dies out if the conditions are not suitable.

THINGS TO TRY

Try growing rice with sand, clay and loam soils with a 80% yield rate. Which of the three is the most water efficient?

By changing the number of plants in the slider, you can notice the spacing between the plants changes as well. The more plants there are the closer together they will be. Try drip irrigation on peppers but change the spacing everytime you try. You will see that the efficiency of irrigation is affected by the proximity of neighbouring plants.

EXTENDING THE MODEL

A button could be added for rain, to introduce a new factor into the model. As of now the model assumes that all water is from artificial irrigation.

Another feature to add would be fertilizers which containt nutrients and chemicals. This could effect the soil content aiding or harming the growth rate of the crops.

This model is a 1 crop farm model. If maybe 2 or 3 types of crops were grown together on the farm that might have interesting effects on the water usage. Alernate croppping is practiced in the real world so to have an extension on that would be useful.

NETLOGO FEATURES

The model has 3 BehaviorSpace experiments. They vary the period and irrigation per patch parameters for the three different crops - rice, maize and peppers - to find the optimal combination that maximizes yield and efficiency. Behavior Space allows the developer to test the model with a very wide range of parameters automatically. This feature is very useful because you can get insights and findings from combinations that you might not have tried manually.

Another feature that is really interesting is the the colors. The patches change shades of brown based on their water content. Netlogo's brown shades range from 30 to 39. I was able to use this window to vary the colors gradually. I find this feature particularly useful as it is different from the hex rbg color code systems.

RELATED MODELS

Percolation Model fromt the Netlogo Model Library

CREDITS AND REFERENCES

Brouwer, C. J. Irrigation Water Management: Irrigation Methods. Rome: Food and Agriculture Organization of the United Nations, 1985. www.fao.org. Food and Agricultural Organization of the United Nations. Web. 2 June 2016.

This model would have not been possible without the guidance of Uri Wilensky, Artur Hjorth, Bryan Head and Elhem Beheshti.

Comments and Questions

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turtles-own
[
 pmin-water-content ; min water content of patch its on in order to live
 pmax-water-content ; max water content of patch its on in order to live
 cur-water-content ; current water content of turtle
]

patches-own
[
 pwater-content ; patche's water content
]

globals
[
  avg-cur-water-content ;avg water content of patches
  total-water-used-in-irrgn ;total water used in irrigation
  total-killed-from-excess-water ;number of plants killed from excess water
  total-killed-from-less-water ;number of plants killed from less water
  total-water-used-by-crops ; total water used by crop
  total-water-on-farm ; total water content of farm
  time ; time in the simulation. = number of ticks
  abs-rate
  abs-success
  efficiency ; outout measure
  crop-lifespan ; lifespan of current crop
]

to setup
  clear-all
  ;;maize
  if crop-type = "maize" [ ; if maize crop set maize properties
    create-turtles num-plants [
      set shape "plant"
      setxy random-xcor random-ycor
      set crop-lifespan 1300
      set pmin-water-content 100 + random 10
      set pmax-water-content 700 + random 100
      set cur-water-content 300 + random 50
      set color green
    ]
  ]

  ;;peppers
  if crop-type = "peppers" [ ; if pepper crop set pepper properties
    create-turtles num-plants [
      set shape "plant"
      setxy random-xcor random-ycor
      set crop-lifespan 1500
      set pmin-water-content 100 + random 10
      set pmax-water-content 600 + random 100
      set cur-water-content 300 + random 100
      set color blue
    ]
  ]

  ;; rice
  if crop-type = "rice" [ ;set rice properties
    create-turtles num-plants [
      set shape "plant"
      setxy random-xcor random-ycor
      set crop-lifespan 1200
      set pmin-water-content 150 + random 15
      set pmax-water-content 800 + random 100
      set cur-water-content 400 + random 100
      set color red
    ]
  ]
  set total-water-on-farm 0
  ask patches [ ;get total water on farm
    set pwater-content 180 + random 40
    set total-water-on-farm total-water-on-farm + pwater-content
    set pcolor (39.9 - pwater-content / 100 )
  ]
  get-avg-cur-water-content
  set abs-rate 3
  set abs-success 0
  set total-water-used-in-irrgn (sum [pwater-content] of patches)
  set total-killed-from-excess-water 0
  set total-killed-from-less-water 0
  set total-water-used-by-crops 0
  set time 0
  set efficiency 0 ;getter defined below
  set-arrangement
  reset-ticks
end 


;; set arrangment or formation of crops based on input

to set-arrangement
  if arrangement = "rows" [setup-rows]
  if arrangement = "evenspread" [setup-es]
end 

;; setup equally spaced rows

to setup-rows
  let num-rows 9 ; number of rows to create
  let total-turtles count turtles
  let x-spacing (max-pxcor - min-pxcor) / num-rows ;space between the rows

  ask turtles [
    foreach [0 1 2 3 4 5 6 7]
    [
      if who >= (? * total-turtles / (num-rows - 1)) and who < ((? + 1) * total-turtles / (num-rows - 1))[
        set xcor min-pxcor + x-spacing * (? + 1)
      ]

    ]
    set ycor (min-pycor + ((who mod (total-turtles / (num-rows - 1))) / (total-turtles / (num-rows - 1))) * max-pycor * 2)
  ]
end 

;; set up turtles equally spead out equispread arrangment

to setup-es
  let num-rows 24
  let total-turtles count turtles
  let x-spacing (max-pxcor - min-pxcor) / num-rows

  ask turtles [

    foreach [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22]
    [

      if who >= (? * total-turtles / (num-rows - 1)) and who < ((? + 1) * total-turtles / (num-rows - 1))[
        set xcor min-pxcor + x-spacing * (? + 1)
      ]

    ]
    set ycor (min-pycor + ((who mod (total-turtles / (num-rows - 1))) / (total-turtles / (num-rows - 1))) * max-pycor * 2)
  ]
end 

to go

  if count turtles <= 1 [ stop ] ; if all plants dead
  if time >= crop-lifespan [ stop ] ;life cycle of crop finished

  diffuse pwater-content 0.1
  check-water
  irrigate
  absorb-water
  use-water
  patches-lose-water
  evaporation
  recolor-patches
  get-avg-cur-water-content
  get-eff
  get-total-water-on-farm
  set time time + 1
  tick
end 

; patches lose water to earth

to patches-lose-water ;; patch procedure
  if soil-type = "sand" [
    ask patches [
      set pwater-content pwater-content - 0.3
    ]
  ]
  if soil-type = "loam" [
    ask patches [
      set pwater-content pwater-content - 0.2
    ]
  ]
  if soil-type = "clay" [
    ask patches [
      set pwater-content pwater-content - 0.1
    ]
  ]
  recolor-patches
end 

; check water at turtles patch. die accordingly

to check-water ;; turtle procedure
  ;; check if there is too much water on the turtle's patch
  ask turtles [
    let flag 0
    let y pmax-water-content
    ask patch-here [
      if pwater-content > y [
        set flag 1
      ]
    ]
    if flag = 1[
      set total-killed-from-excess-water total-killed-from-excess-water + 1

      die
    ]

  ]

  ;; check if too little water for turtle
  ask turtles [
    let flag 0
    let x pmin-water-content
    ask patch-here [
      if pwater-content < x [
        set flag 1
      ]
    ]
    if flag = 1[
      set total-killed-from-less-water total-killed-from-less-water + 1
      die
    ]
  ]
end 

; turtles use the water they absorb

to use-water ;; turtle procedure
  ask turtles [
    set cur-water-content cur-water-content - abs-rate
  ]
end 


; absorb water from soil

to absorb-water ;; turtle procedure
  ask turtles[
    set abs-success 0
    let abss 0
    ask patch-here[
      if pwater-content > abs-rate [

        set pwater-content pwater-content - abs-rate

        set abss 1
        ]
      set abs-success 1
      ]
    if abss = 1 [

      set cur-water-content cur-water-content + abs-rate
      set total-water-used-by-crops total-water-used-by-crops + abs-rate
    ]
    set abs-success 0
    set abss 0

  ]
end 

to evaporation ;; patch procedure
  ask patches [
    ifelse pwater-content >= evaporation-rate [
      set pwater-content pwater-content - evaporation-rate
    ]
    [
      set pwater-content 0
    ]
  ]
end 

to irrigate
  if periodic [
    ;;; repeat the irrigation
    if ticks mod period = 0 [
      if irrigation-type = "drip" [drip-irrigation]
      if irrigation-type = "surface" [surf-irrigation]
      if irrigation-type = "channel" [channel-irrigation]
    ]
  ]
end 

;; surface irrigation. add water to every patch

to surf-irrigation ;; patch procedure
  ;;; add water to every patch
  ask patches [
    set pwater-content pwater-content + irrigation-per-patch
    set total-water-used-in-irrgn total-water-used-in-irrgn + irrigation-per-patch
  ]
  recolor-patches
end 

;; add water to those patches with turtles on them

to drip-irrigation ;; patch procedure
  ask patches [
    if count turtles-here > 0 [
      set pwater-content pwater-content + irrigation-per-patch
      set total-water-used-in-irrgn total-water-used-in-irrgn + irrigation-per-patch
    ]
  ]
   recolor-patches
end 

;; add water in vertical lines

to channel-irrigation ;; patch procedure

  ask patches [
    let x-spacing (max-pxcor - min-pxcor) / 7 ;;9 channels

    if member? pxcor [0 4 7 11 14 -4 -7 -11 -14]
    [
      set pwater-content pwater-content + irrigation-per-patch
      set total-water-used-in-irrgn total-water-used-in-irrgn + irrigation-per-patch
    ]
  ]
   recolor-patches
end 

; calcualtes the irrigation efficiency

to get-eff
  set efficiency (total-water-used-by-crops / total-water-used-in-irrgn) * 100
end 

;total water on farm is sum of pwaterc-content of patches

to get-total-water-on-farm
  set total-water-on-farm (sum [pwater-content] of patches)
end 

;; scale the patch colors from light to dark brown based on water content

to recolor-patches ;; patch procedure
  ask patches [
    set pcolor (39.9 - pwater-content / 100 )
  ]
end 

;getter function

to get-avg-cur-water-content
  if count turtles > 0 [
    set avg-cur-water-content (mean [cur-water-content] of turtles)
  ]
end

There are 6 versions of this model.

Uploaded by	When	Description	Download
Jaiveer Kothari	about 9 years ago	Final Project Latest Version	Download this version
Jaiveer Kothari	about 9 years ago	Final Project	Download this version
Jaiveer Kothari	about 9 years ago	version 4	Download this version
Jaiveer Kothari	over 9 years ago	version 3	Download this version
Jaiveer Kothari	over 9 years ago	Version 2	Download this version
Jaiveer Kothari	over 9 years ago	Initial upload	Download this version

Attached files

File	Type	Description	Last updated
JaiveerKothari-FinalProjectReport.pdf	pdf	Final Report	about 9 years ago, by Jaiveer Kothari	Download

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