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Comment by turnsout | Hacker News Reader

Works really well as long as you can find trees that don't consume water.

The challenge in these western cities is that they don't even have enough water to run the taps. The reality is that the western US should not be this populated, period.

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The vast majority of water in western US goes to agriculture. You can of course make the obvious argument about local food production being necessary, but if the choice is more people can drink water at the cost of more expensive almonds and alfalfa, I'm ok with that. The idea that the west has done anywhere close to enough to optimize water consumption is not right, there's quite a bit of headroom left (that should be used to replenish aquifers).

People might think you're being hyperbolic about the alfalfa but you are not. 25% of Colorado River water is used to grow alfalfa which is crazy given the contention around Colorado River water rights.

https://coloradosun.com/2024/04/04/research-colorado-river-w...

One of the more enduring way of restoring the aquifer is to restore the riverlands the way it had been before we hunted out all the beavers. That is, to slow down water flow in the hydrological cycle so that it spreads out and meanders throughout the land.

I live in Portland, a place covered in trees and there’s definitely plenty of water for them. When I travel through parts of East Portland, it’s very noticeably hotter and there’s a noticeable lack of trees. The problem seems to be part political, part budget and part passing the buck (BUT WHOS GONNA TAKE CARE OF THEM??). It’s very frustrating.

True, I should have been more precise; I was talking about the southwest. The PNW is a wonderland.

That's exactly what Phoenix is doing[1], well not no water but they're native and use very little.

[1] https://www.phoenix.gov/oepsite/Documents/Tree%20and%20Shade...

I live in Phoenix, and have seen the tree planting.

There is a lot more that could be done that is not done. From my eyes, it looks more like, there are X number of trees that need to be planted and they are planted to fulfill those goals.

There is little in the way of consideration for sunlight patterns, rainwater patterns, microclimates, planting methods, etc.

While imperfect sounding, just getting trees in the ground and then moving the goalposts to constantly increase the number, is a huge step forward. I think once in the ground, nature will take over and adapt.

The desert has always been a place humans needed technology to thrive in, since the ancient Gardens of Babylon or the Phoenix canals constructed by the Native Americans. The challenge is we need to invest in technology (Did you know the AZ border is only 60 miles from the Sea of Cortez?).

There are lots of solutions that don’t involve throwing our hands up and saying “aw shucks it’s too hard to build infrastructure so I guess we should go home”

Which cities? Metro Phoenix non-agricultural water usage is flat over the past 30 or 40 years despite experiencing double digit population growth for most of that time. Agriculture is the majority consumer and incentives and stewardship norms are evolving.

Treated wastewater is almost waste itself, because at least in the United States we're reluctant to use it for agriculture for the obvious reasons. And trees aren't particularly large consumers of water, because the irrigation methods are non-lossy. Not spraying sprinklers up in the air so half is lost to evap. Or flooding little furrows in between the rows of a crop. It's not that big of a challenge, at least water wise. Infrastructure, if anything, is the problem... cities would have to go digging up a fuckton of sidewalk, and spend extra on maintenance every time there's a leak. Worse still, is having two separate water systems (can't connect to the potable water mains).

Drip irrigation isn't always good for trees to develop robust root system.

Wastewater depends ... residential greywater can be used onsite if the residents are careful about the type of detergents they use. There are methods to treat blackwater onsite (more than just a septic tank and a leech field).

For trees, I think the biggest factor is if you use woodchips in a basin. Even a six-foot diameter with 1 ft depth, filled with arborist chips makes a huge difference in water retention and nutrition for the trees. These are rain water harvesting structures that do not require a drip system.

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