Using evapotranspiration (ET) is the most important part of setting up your irrigation system to conserve water. Replacing what the plant uses each day is much more accurate than just running heads for a set amount of time. Your computer can do the proper calculation each night and assign run times to each station. Being able to make the course dry and firm evenly across the course is the goal and making fine tune adjustments to achieve this quality is much easier without doing chunky adjustments with individual run times but with percentages of ET.
The ET rate throughout your course will change by each microclimate and that is where individual head control can help. Adjusting these heads to match your problem areas are the key to balance and uniform playing conditions. Hillsides for example will have a higher ET rate where valley may be lower.
ET is a dynamic value automatically adjusting to your current conditions. This is why it will help you save water. Each day it will calculate the ET and make the global adjustment changing every heads run time. Running heads according to time intervals is much more crude and results in inefficient watering and water waste.
Not only is ET the key to water savings. Even though this is a huge factor it is only as good as your computer’s database. Each head has a designation to let the computer know what it is turning on so it can determine the amount of time it needs to run for and how much water it will apply. With my case every head was using a default setting, not accurate to what was in the field. This resulted in the expected water usage produced by the computer to not match the actual usage from the pump station. This also handicapped me in the use of ET.
I went through each individual head and corrected the computer’s database to match what we had in the field. It is a very tedious project since head type, nozzle type and arc are all required. Rainbird also has another variable with the poppet in the bottom of the internal that also must be correct for the nozzle type. Once all the heads were correct in the computer the estimated water usage came within a few thousand gallons of the actual usage which could be due to nozzle wear and other minor things.
The next area we targeted were arc and pressure adjustments. Since we have a desert style course with basically islands of turf we have many more part circle heads than full circle heads. Each head runs along our native areas to water the adjacent turf. We went through each head and found that many heads were out of adjustment. Making these small adjustments to follow the turf line better adds up to decent water savings. Just that fraction of run time going into the native areas can be several gallons lost.
Pressure adjustment should be checked on all the heads. The newer style has a better setup with designated pressure but the older styles have an adjustment screw to adjust your pressure. Since the database requires pressure used to calculate amount of water applied it is important that each head matches your computer settings. Even 10 psi can cause an area to be inconsistent causing you to make unnecessary percentage adjustments which leads to extra water usage. It is amazing how finicky irrigation can be, when you have everything matching it is nice how accurate it can be.
The final area to check on your central control is the hydraulic tree. This also tells the computer how many heads it can afford to run in any given area to ensure water does not travel through the pipes at a speed greater than five feet per second. Anything more will result in premature wear and tear on the system. This data, if incorrect, can affect operating pressure in the field by turning on too many stations when your program is in full force. This can be just enough to water a fairway poorly and again lead to unnecessary percentage adjustments.
There are many factors when applying water to your golf course. The central control only knows what you tell it to know. If it is improperly programmed thousands of gallons could go to waste without noticing. Central control is the heart of the golf course and can be very complicated, but with a little time and effort you could save thousands of gallons by using you irrigation program to it’s fullest.