Most city dwellers do not have the training, management skills, motivation, or time to manage drip irrigation systems. This is not to say that no city dwellers are capable of maintaining drip irrigation systems. Water requirements of plants. We can calculate the water requirements of desert plants. Let D equal the diameter of the plant in feet.
Diameter is the distance from one edge of the canopy to the other.
The following equation can be used to calculate the amount of water required by a plant per day. For example, the following calculation would be made for a tree with a 10 ft diameter canopy. The principle of conservation of mass can be used to calculate the plant water balance. The plant has a reservoir below the plant in the soil that can store water. Now, let us assume that the 10 ft diameter tree is irrigated with the single emitter with a 2 ft diameter.