Andrés Bernal wrote:In this video
Geoff Lawton shows how some of the earthworks made back then to fix this problem in Arizona are still functioning.
I've seen other videos on this area before, with Mollison and others, and I've never really talked about my opinion on them, I think. But what with the discussion on the dust bowl here, I thought it'd be a good time to throw my 2 cents in. I live in this area, know a lot about the local plants and animals (not an expert, but I pay attention, basically), so I'm gonna talk about what I know.
First, I feel rather bad for how Tucson gets portrayed in this video. Because while as a city it definitely still has problems with how water is handled, it's actually got less control than is sort of implied, and what control it does have, it's heading in good directions at least.
Tucson is in a state that is controlled by a lot of wealthy folks who do not give a crud about conservation, of water or much else. So even though Lawton showed that shot of a lush golf course in Tucson, Tucson itself has no control of that. Golf course water usage can't be curtailed by the cities - it's a state regulation, so Tucson has no say in how much water the golf courses in or near it can use.
Tucson IS using too much pumped out water. That's definitely a problem. But it also has a very active water conservation scene in this city - I think more active than almost anywhere in the state. So it has been making changes to try and incentivize both lowering water usage AND refilling the aquifer, up to and including water harvesting infrastructure for roadworks and commercial buildings. Brad Lancaster (the author of Rainwater Harvesting for Drylands) lives in the city and is one of many that have pushed for water conservation reforms to the city building code and more.
They also have been trying to work a lot more with reclaimed water so that the water used isn't lost forever. So in Tucson is a place called the Sweetwater Wetlands that is an artificially constructed wetland using reclaimed water (https://tucsonaudubon.org/go-birding/get-started-with-birding/great-places-to-bird/sweetwater-wetlands/
). Salinity issues exist, and are partially addressed by native plants that thrive in higher salinity environments to make it easier for other plants to grow as well (like saltbushes).
And in the same river that Lawton stood in, as of 2019, the Santa Cruz River Heritage Project has been pumping water back into the river, from reclaimed water, to flow near the edge of Tucson and OUT of Tucson. I do not know what salinity issues there may be, but it's spawned a lot of growth in that area, so it's been at least somewhat of a success, so far. (https://www.tucsonaz.gov/files/water/docs/SCRHP_article_World_Water.pdf
I am not saying that Tucson is great - its water usage is not sustainable. I just felt bad that the city that has such a strong water conservation gig going mostly had the focus on golf courses and pavement, you know?
But that said, this was not the main issue with this video.
The big problem I have with this video is the very reason the video exists: the swales.
There was a lot of talk about how lush they made the area, how rich the soil, how full of plant life, etc...
And most of that's true. The soil there is MUCH better than the rest of the surrounding area. A lot of water collected there; a lot of plants can grow there.
But...well, I'm just gonna use an example to show why I really, really dislike how these swales are talked about.
The Santa Cruz river bed - the dry one that Lawton was standing in for part of the video? Lawton implies that it's dry due to a number of factors.
That is not true, however. That river went dry pretty much due to one action taken by a group of businessmen in 1910 - 19 wells dug to collect water around the springs that were the source of this river. The water was sent via canal to various buyers in the valley. It took them 5 years to use up the water so completely that the springs went dry, and so did the river. So this river has been dry since 1915.
This is what happens here in the desert, though. We have LIMITED WATER. There is not a single water source here that is kept full of water from rainfall alone. All of the year-round flowing water near here is, and was, from underground springs - and there IS no year round source of running water in this valley. The Santa Cruz river was IT.
So the vast majority of the water that the plants and animals use in the desert comes from rainfall, instead. It comes mostly, and sometimes only, for three months in a row in the middle of the summer. Most of the rainstorms will drop rain in small areas, and then the water gets distributed throughout the desert via the arroyos that are dry whenever it is not raining.
Arroyos are an integral part of this desert. They are one of the reasons that the desert has the level of growth it does - which is, as I understand it, higher than almost any desert in the world. They may not be running with water all year round, but for the desert, they are as much a source of life as a regular stream or river would be in a non-desert environment.
So blocking an arroyo, especially a large one, is about as beneficial to the environment as, say...digging 19 wells and draining a spring dry. Which is why the swales - which blocked arroyos - are actually rather awful.
Because BOTH the swales AND the wells draining the springs put extra water SOMEWHERE. They made more plants grow SOMEWHERE.
But they only managed it by taking that water AWAY from everything downstream that used to depend on it. This is not, IMO, a good thing.
If I have water fall on my property and I dig in basins so it is more likely to collect in specific spots, or more likely to collect and soak in than evaporate off the surface? That's good for me and the plants and animals on my property. That's a pretty natural occurrence that I'm just helping along. Same for if there is water that falls ON my property, and I make sure it doesn't run OFF of it.
But there is no such things as making this entire desert lush and looking like that basin behind the swales, not without screwing over other parts of the environment. We do not have enough water in the desert to DO that. The more extreme we make our water collection, in terms of blocking flowing water for our use, the more we take away from elsewhere.
Like, just as an example, that amaranth he points out? It looks like Palmer's Amaranth. It grows freaking everywhere - richness of the soil is not in anyway a necessity for them to grow that thick and tall. Water is the determining factor.
They grow that tall and big along numerous arroyos near my house that only have water for maybe 2-3 weeks a YEAR and the crappiest soil imaginable. They grow in bigger patches when there is more available water, and in smaller patches - including just a few plants - where there is less water. And they are ONLY that lush for a short period of the year. Same for the grass - edges of many, many roads, where there is just a little more water, look just as lush and full of grass and amaranth during the monsoon season as the middle of his swale.
So you can have that swale with a lot of concentrated amaranth...or you could have NOT had that swale and the amaranth would have grown in much smaller patches along miles of arroyo downstream, to be used by a lot more animals, and slightly improved the soil everywhere a little bit, instead of one big patch of 'rich' soil. You could have added bits of stone and other things to slow down the water just a bit, so that the edges of the arroyos had more growth and less erosion, if one wanted to encourage a greener desert.
But the only way to have that dream that Lawton talks about, planting citrus and figs and 'maybe dates,' is if you essentially grab the water in your area, PLUS block water flow from some arroyo.
Oh...and you irrigate.
You're not having pretty much any fruit tree growing here without irrigation of some kind. I don't care HOW rich the soil is - the humidity is too low and the rainfall is too low for the majority of the year...maybe I'm wrong, but I'm guessing that even with extremely rich soil and a bit of shade, a citrus tree is going to struggle with high temperatures, humidity sometimes in the single digits, and not a single extra drop of water for, say, 7-8 months straight.
So...yeah, I know I'm going off a bit here. I find it hard not to, honestly, because I keep seeing videos like this, and then I hear folks get caught up in the idea of 'greening the desert' as something we can do in our area as though it will not have any impact on the rest of the environment around us.
That is not how it works. We CAN have more lush areas in the desert. But to get them to the extent suggested in the video? In the end, we'd have a small bunch of really lush, green areas, and a much drier, deader desert all around them. Which is not a good trade off.