Cannabis Cultivation in California
A dive into how remote sensing and cartography can be used to give an estimated perimeter of where cannabis farms are likely to be found.
Introduction
After the legalization of marijuana in California many of the black-market sellers did not quit. In fact, many of them took the opportunity and moved to hot dry deserts, such as the Mojave desert, where massive farms built.
The oils from the weed is used to make popular products such as edibles and vaping cartridges, which are shipped in trucks and cars to legal dispensaries in California and across the country.
This was said in a Los Angeles Times article , which also stated that even though many believed legalizing weed would reduce crime, it ended up leading to a growth in the black market. Not only do these farms harm the economy, but also lead to the death of individuals who approach or go near these farms.
Knowing that cannabis is still growing in the black-market, it is safe to say more and more people would try to take advantage of it. This is why being able to use remote sensing and cartography to show likely locations of natural/illegal cannabis being grown in California would help prevent individuals from running into trouble and informing authorities where to keep an eye out for.
A Look Into Cannabis Sites
Cannabis sites typically have some features which help indicate if it is a regular plantation or cannabis farm. To begin, the plants are often found in a grid patterns which are consistent in color, shape and size.
Near the area of the site there is usually a water source. Most of the time it will be a water tank or a river/stream nearby where water is transported.
Furthermore, the area where the plants are found are likely to be cleared out and a greenhouse can be found.
Effects of Cannabis Sites
Cannabis comes with a cost, especially for the environment and the people around it. The US Forest Service reported that in 2012 over 315,000 feet of plastic hose was collected, 19,000 pounds of fertilizer and 180,000 pounds of trash was found after 300 marijuana plantations were seized.
All this trash effects the ecosystem around the sites. Things such as fertilizer can contaminate and poison water sources nearby. Which not only hurts the growth of other plants, but any animals or humans passing by could be poisoned.
Furthermore, cannabis requires a large uptake of water, 22.7 liters, which is near double what normal plants being grown would require. Being in California where there is a drought, it doesn't help that large amounts of water is being used to help grow and maintain illegally grown cannabis.
Potential Growth Perimeter Map
After looking at the problems and concerns raised by cannabis sites, research was done to help locate overlooked general areas where cannabis can be grown. After a good understanding of the environment needed for cannabis to naturally grow, using the ArcGIS Pro software a map utilizing different layers helped narrow down where cannabis sites would be best suited for.
Building the Map
To begin building a map, basic ranking of data has to be created which helps give an idea of what we should look for to pick the optimal locations.
Conditions that have to be met:
- Temperature between 12℃ and 30℃
- 40-50% Humidity
- Soil pH of 5-7
- Slopes can't be steeper than 15°
- Area has to receive over 100mm of rain every year
- Area can't be developed, under water, icy or barren land
- Near stream/river or bodies of water
Optimal Humidity, Temperature, Slope and Precipitation
The Current Weather and Wind Station Data was an ultimate asset in locating feasible areas for cannabis. Through the use of filters and definition query the optimal conditions could be set.
- Temperature between 12℃ and 30℃
- Over 100m annual precipitation
- 40-50% Humidity
The areas which meet these conditions are then displayed as a heat map. (shown as blue circles on the map)
Avoiding Developed Areas
Next, we have to meet the condition
- Area can't be developed, under water, icy or barren land
To filter out areas that are developed we can use the USA Urban Areas layer which provides a gray overlay to help distinguish areas which are developed. This is determined by taking into account the population density in the area.
As for the under water, icy and barren land we can use the base-map and imagery to work around those.
River, Streams, Water
Now that we have the central conditions prepared we can go further and find a source of water. Finding a river, stream, or a body of water helps eliminate the need for large water tanks which would be makes it efficient for cultivating cannabis.
The USA Rivers and Streams layer does a great job in showing water features for a geographic display.
Zoom in to the opaque lines found all throughout California, those are all rivers and streams!
Picking Optimal Areas
Now that we have setup nearly every condition we can put all the layers together and locate a few optimal areas.
In order to pick potential grow areas we have to be near the blue heat-map (areas with optimal temperature, precipitation, and humidity)
Then, we make sure to avoid any developed area, under water, icy or barren areas.
Attempt to stay near a river, stream or body of water.
Finally, we'll check the pH and slope.
First Area
Using all the conditions above we can start pinning locations that could work as a site for cannabis. Here we have the first potential area that can have a cannabis site.
Final Check
Now that we checked that all the conditions are met and the areas have been mapped we can look at it using imagery.
As you can see, there is a lot of land and a lot of area to cover. In fact, looking through these areas could possibly lead to locating an illegal cultivation!
Conclusion and Looking Forward
Pinpointing the exact location of cultivation sites is very difficult, however getting a general area of an optimal location isn't. This proved to be true after creating this map and looking at the corresponding imagery of the locations plotted. Looking forward, the map will be continuously updated through the use of Python. Layers will be regularly checked and maintained. The goal of this project is to raise awareness of the amazing capabilities of remote sensing and hopefully show a couple areas people should be aware of next time they go exploring!
