An irrigation canal like this is a big ditch to move water from a river to near farm fields. Without the extra water taken from the river, there wouldn’t be enough water in the soil for crops to grow in the area.
Being a big ditch open to the sky, the hot sun and dry air make a bunch of the irrigation water evaporate before it even gets to the field. So we went to all the effort of taking water out of the river just to waste it humidifying the nearby air.
Why did we do it in the first place? Because it’s way easier and cheaper to dig a ditch than to lay a big pipe, and I don’t know if the US had any other water-delivery tech at the right scale when these were built.
There probably are, but Saudi Arabia owns a bunch of land in Arizona and decided it was the perfect place to grow alfalfa, a very water intensive crop. That said, some farming does make some sense even in the desert, since it is almost certainly cheaper to have local produce than to need to import everything from places that have an abundance of water, even if that means building canals to water them.
The US has lots of land that doesn’t require irrigation, but also lots of land that can grow crops if irrigated. Some of that land in California is some of the best farmland in the whole country, growing things that prefer California’s Mediterranean climate (similar to parts of Australia’s southwest coast).
We have the technology and have had it for a while. But we don’t have the laws and habits of dry countries so US water laws are a wasteful mess.
An irrigation canal like this is a big ditch to move water from a river to near farm fields. Without the extra water taken from the river, there wouldn’t be enough water in the soil for crops to grow in the area.
Being a big ditch open to the sky, the hot sun and dry air make a bunch of the irrigation water evaporate before it even gets to the field. So we went to all the effort of taking water out of the river just to waste it humidifying the nearby air.
Why did we do it in the first place? Because it’s way easier and cheaper to dig a ditch than to lay a big pipe, and I don’t know if the US had any other water-delivery tech at the right scale when these were built.
Are there not enough areas of the US that get rainfall suitable for growing the needed food?
There probably are, but Saudi Arabia owns a bunch of land in Arizona and decided it was the perfect place to grow alfalfa, a very water intensive crop. That said, some farming does make some sense even in the desert, since it is almost certainly cheaper to have local produce than to need to import everything from places that have an abundance of water, even if that means building canals to water them.
The US has lots of land that doesn’t require irrigation, but also lots of land that can grow crops if irrigated. Some of that land in California is some of the best farmland in the whole country, growing things that prefer California’s Mediterranean climate (similar to parts of Australia’s southwest coast).
We have the technology and have had it for a while. But we don’t have the laws and habits of dry countries so US water laws are a wasteful mess.
Almost everything West of the Colorado Rocky mountains is very arid and requires extensive irrigation.
Everything except for the Pacific Northwest, and only the area west of the Cascade mountain range in Oregon and Washington.