Friday, June 13, 2008

Going around in Circles

When I came out to the desert, I had certain preconceived notions, like there would be lots of cacti (nope), that it would be really hot (yep, at least in summer), that it would be boring (nope), and there would be lots of wide, open spaces with big skies and few people (yep). At least that last part is true where I live. And the reason is that there just isn't much water. In the state of Nevada, only 11% of the land is private, and most of that is near water. The early settlers knew that they couldn't survive without it, so they put down their roots in those wet places.

They planted gardens and orchards to feed themselves, and they planted fields in order to feed their livestock during the winter months. With not enough precipitation to have the fields grow on their own, the settlers diverted streams to water the fields. This so-called flood irrigation used simple technology at first. Today it is more complex, using laser levels to get the fields to the right slope and time-operated gates to allow water onto the field for a certain amount of time. Generally flood irrigation is time consuming, requiring people to move water around. Wildlife flock to the open water on the fields. 

As technology improved, hand lines became popular to spread the water more efficiently. Basically these are pipes with sprinkler heads placed along the pipes. The pipes latch together, so when a different section needs to be watered, the pipe is taken apart and moved. Slightly less work intensive are wheel lines, which have a small motor that move the pipes across the field. 

Two wheel lines can be seen in this photo. The small specks in the middle of the field are pronghorn antelope enjoying an easy meal.

Technology improved, and center pivot irrigation was born. The large circle fields that you can see from airplanes are the pivots. A tower in the middle of the field is the central point, and the water is sent through a galvanized steel pipe that is supported by trusses mounted on wheeled towers that go around and around. Sprinklers are spaced along the pipe. Pivots generally cover 90 to 180 acres.
When I first came out here, I wondered why the water was going all day long. Why not just water at night, when there would be less evaporation? It turns out that it can take up to seven days for a pivot to make a complete circle, and in order to get enough water on the fields, the water has to run both day and night.
To help reduce the amount of evaporation, hoses called goosenecks extend down from the water pipe to spray water closer to the ground. As the pivot moves around the field, water in the center sprays for less time than on the outer spans so that the entire field is watered evenly. Even by using water more sparingly, there are still few people who live out here in this rural area, due to the scarcity of water. Despite the internet and phones that make life seem "civilized," it still feels a little old-fashioned to live in a place that has the same population as it did roughly 150 years ago. 

Tomorrow: Nature Boy on tractors


Sylvia said...

Very interesting and beautiful photos.

Germaine S said...

And Vegas wants what little water that you have. Shame on them!

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