As Waterwise registered garden irrigators, our core focus when installing or upgrading any irrigation system, is watering efficiency.
What is watering efficiency in irrigation?
A correctly installed and designed irrigation system, will deliver the exact amount of water to your garden beds and lawns, that's needed to support plants, trees or lawns,
There are many factors to consider when determining how much water is required for each retic station, including but not limited to lawn type, plant types, soil types, clay content, run off (sloping lawns), use of mulch, exposure to sun light etc.
Once you have determined how many MLs of water are required the next stage is to identify the most efficient way of delivering that water, avoiding wastage, over spray, run off and over watering.
Sprinkler types
There are many variations of what most people refer to as sprinkler types. Larger commercial installations use gear driven sprinklers, and emit a heavy get of water that can be set to rotate from 45 to 360 degrees. The most common sprinklers used in lawns are pop up sprinklers, usually installed just below the surface height of the lawn to avoid damage from lawn mowers or vehicles, but high enough and spec'd tall enough to pop up above the lawn height and give a balanced spray pattern.
These pop up sprinklers can be fitted with either fixed spray conventional nozzles which will emit a large but fine spray pattern across a predetermined pattern. Fixed spray nozzles are reliable, and if spec'd correctly can offer a quick and stable pattern of water, and they're readily available at very attractive prices. However sprinkler head technology is evolving all the time, and there are now far more efficient solutions, such as the Rainbird R-Van rotary nozzles, or MP Rotators. Both of these sprinkler heads are designed to emit jets of water likened to fingers. Fine concentrated lines of water which can be easily adjust to any pattern of watering from 1 to 360 degrees.
These new rotary nozzles have many distinct advantages. Firstly the fingers of water are far less susceptible to being diverted by high winds. Fixed sprays create a mist which can easily be blown off target in high winds, a particular problem in coastal reticulation installations. The rotary nozzles also emit a lot less water per minute. A typical fixed spray 360 degree nozzle might emit 8 litres per min, however an MP rotator of the same spray pattern may only emit 4 litres per minute.
We can use these lower flow rate sprinklers to our advantage. For instance if your lawn is on a slope, running fixed sprays will deliver 80 litres of water per each full circle within 10 minutes. This is a lot of water for your lawn to absorb, and if you were to test this theory by taking a bucket and tipping 80 litres on to a sloped lawn over a 10 minute period, you would at least 1/3 of the water run off the lawn and on to the road. By emitting less water per minute, but over a longer time, you are giving your lawn time to absorb the water, and feed the root system, rather than just run off down the drain.
Ultimately, the aim is to give your lawns approximately 10ml of water during your reticulation cycle, and to reduce the loss of water as much as practicable in the process. We have found that rotary nozzles such as the Rainbird R-Van or MP Rotators are the most effective way of doing this.
In our next blog we will be looking at watering efficiencies in garden beds, with a particular focus on drip irrigation.