Real-Life Math
The science of irrigation control is based on getting the right
amounts of water to the right places at the right times. It sounds pretty
easy. Turn the hose on, adjust the flow and let it run until the ground is
saturated. At least, that's what you thought when you first decided to
become an irrigation specialist.
That was then. This is now. As you
sit in front of the design plans you are working on, you wonder how you could
not have known how many variables were involved in figuring out what is the
right amount of water.
How and when do you turn the hose on? How much
is the right amount of water? How long does the water need to flow to get
the soil saturated at the optimum rate for the plants?
Shaking your
head, you focus back on the plans in front of you. Your current problem has
to do with irrigating crops properly. You're designing a pump that will
push water into irrigation channels. The channels, which are actually pipes,
are designed to let water flow through them in thin streams that help to saturate
the ground more efficiently.
But is your pump pushing water too fast
or too slow? If the water is being pushed through the system too quickly,
it will just run off rather than soak into the field. You'll
accomplish nothing more than wasting the water used.
However, if the
water is not pushed quickly enough, the irrigation system won't function
properly and the water will puddle. The result will be areas that are over-watered
and areas that are under-watered.
You know that to effectively saturate
the entire field, 12,000 gallons of water has to pass through the irrigation
channels. You also know that if more than 500 gallons of water passes through
the channel per minute, the water will run off the field rather than being
soaked into it. And using your system, it takes about 2.75 hours to properly
spread 12,000 gallons of water on the field.
Is your system pushing
the water at a rate that will allow the water to soak into the ground rather
than running off?
"The mathematics involved in irrigation work is getting
into calculating the amount of moisture in the soil. You use a formula --
a basic equation that you have to solve," says Laurie Tollefson. He is an
irrigation specialist. "You must be able to use and have some understanding
of mathematics to do this kind of work."