I'm still searching for land to look into for a homestead and I came across an interesting plot with cheap land fairly close to town. I know why it's cheap, its on a flood plain. Most of the land around here(southern AZ) is because it's relatively flat and during monsoons it will sheet flood. I am watching permaculture videos to get as much education as I can so I want to run through a scenario with this land. I may buy it, but the main thing tthat sticks out is the seller put up a lot of great info on the site so it works well for a hypothetical scenario.
Pictures show 2 fairly significant washes running through the property. This is on AO2 and AO3 level floodplain which means 2-3' of flooding is possible in a 1% catastrophic event(or 100 year flood). So the house will have to be built up 2-3 feet on foundation(manufactured home) but I am more curious about how to work the land to negate the affects and take advantage of the water when it is here. The pictures are of the "worse" of the 2 plots of land for sale in the area. One(blue outline on the google map image) is mostly AO2 and higher up out of the floodplain/wash area and the other(red box outline on map) is 90% AO3 with a 1acre spot that is AO2. The image with the road and a ditch along side was because a neighbor dug the ditch to keep people from driving onto the property(older images show lots of circles/doughnuts from trucks or something on the property).
Damn I keep rambling on, anyway... Will swales help soak up water in sheet floods? So it is roughly 660 feet square for both lots(roughly). Another thing is can I connect a swale to a wash? The wash runs along the side of one plot so would a swale touching the wash help divert water or take water from the swale system? Seems like it would take away. Would it be better to stop short of the wash and not mess with it? Is there anything to do in washes to slow the flow of water and help soak more of it into the ground or is it best to let nature do its thing? House placement and roads, if its possible and what I assume is correct, which is a gradual downslope as the land goes north would it be best to make the road come in from the side of the land in between swales and the house closer to the middle of the land? I still need to research house placement for optimum exposure/protection as well. Again this is all hypothetical and even if I do buy the land I am 6-12 months away from buying a house and moving there. I am thinking central to the land(if possible, mostly on the bottom lot, probably have to be SE corner if I took the North lot because of flood plan, etc) to help protect with a swale or two in front of the house to slow water and divert more. I would plan to collect roof water from the house in a cistern to use later.
What else would be good to look into for this type of land?
IF I do buy the land and am 6-12 months away from moving onto it what are some things I could do to kickstart the land while not needed a lot of everyday input? Probably a stupid idea because unless I planted something now before monsoons we would not get enough rain to support anything without water lol. If I found a source of free or cheap mulch and/or horse manure or something like that would it be a good idea to go spread it on that barren area? Would it do much if anything without planting and working the land?
Geoff Lawton and Mollison have both made videos about these swales, which were built as part of the depression era work program under the Civilian Conservation Corps. From my understanding, they were not planted (volunteer planting) and from what I can tell they were not built with key line or anything like that in mind. However, the vegetation is so thick you can't walk inside it. The large, round looking swale furthest east is essentially a horseshoe, and has a grassy field in the middle. It is truly an amazing place and it certainly seems like an effective strategy.
Planning out large, on-contour swales and planting them with the winter or summer rains, certainly seems like a strategy to put on the list for your property. I would suggest having the washes divert into the swales and move that water across the landscape like a rattler moves across the sand. Use that flood plain to your advantage! Draining the swales into the washes may make the washes deeper and wider over time, something you may want to avoid. It might take some time, but getting earthworks built and trees planted might be good first steps.
Awesome! I've seen the videos but the map coords were linked to the old map system and didn't work. Those swales are actually just south of the land I'm looking at. And north of some other land I was looking at. The area definitely has promise. Of course convincing the county to let me build on it because of swales will be tough lol. I would probably look at the lower threat level land for ease of building. The land does seem a little more barren on that lot though. Are you in the Tucson area? I'm wondering what would be good planting to start with, ground cover and trees to get started.
Thanks for the feedback, like I said it's mostly just trying to put knowledge to use and brainstorm what could be done. No guarantee it will be that land but a lot of it is similar.
Yep, in Tucson converting a 1/4 acre barren lot into something less barren and toxic. My best planting advice would be to stick with the native velvet mesquite and ironwood trees, my experience with palo verde trees has always involved a boring beetle that ultimately harms the roots and makes them fall over in the monsoon. Prickly pear, agave, wolf berry, hackberry, greythorn, Sonoran sunflower, mallow are all native food producing plants - plenty more too. With the right strategies, many other desert adapted fruit trees will grow - I grow fig, pomegranate, limon, guava, and quince.
Check out Desert Survivors nursery for native and desert-adapted plants, and of course Native Seeds/SEARCH for your veggie and wildflower needs. I hope that is a start, green that desert!
Much of our land is a drainage and floodplain, and gets catastrophic flooding every few years, and since we've been here there have been 2 FEMA disaster flood events and at least two merely awful flood events, including the past two Springs. I strongly advise against purchasing land in a flood plain, unless you know for certain that your potential house and garden site and access won't be affected by the flooding. I can't speak strongly enough about this. If the real estate disclosure mentions "significant drainage" beware.
Jay, the flood plain maps were redrawn by FEMA and Pima County in 2010 and became official in 2011. These new maps greatly expanded the flood plain areas, much to the consternation of the residents which were impacted by now needing flood plain insurance and disclosure when selling. If you can find the old maps, and compare them to the new maps, it might give you a better historical sense of the flood danger on the land you are looking to buy. For instance, my parcel in central Tucson went from not being anywhere close to a flood plain, to now having half of my property in the new flood plain (which ironically is the highest part). So I just stand on the side that isn't in the flood plain when it rains and I'm good.
As you mentioned in your original post, you will be dealing with sheet flow (at least on the properties in the area you initially proposed). While Tyler's caution is appreciated, the link to the farm wiped out by flooding was in a canyon, which would likely be a bad idea in AZ. The amazing thing about the story Tyler posted is that they rebuilt the farm; not sure I would have come to the same conclusion. Having been on the land in the area that you are considering, it is fairly flat, with a very mild (maybe several feet) slope from east to west. Thus, large berms and basins (similar to the CCC swales) that overflow into one another should work to mitigate flood dangers, while also making use of that water when it does come. Vegetation will help immensely!
Just to be clear, I'm not suggesting that you disregard the flood plain information. I personally believe that given the amount of rainfall here, we need to work with this problem and turn it into a solution. The University of Arizona's very own Gary Paul Nabhan and one of his books 'Growing Food in a Hotter, Drier Land - Lessons from Desert Farmers on Adapting to Climate Uncertainty' has some examples of in-canyon flood plain farming and many other techniques. It's worth a trip to the library.
I agree with you, Jack. The steepness of the land is a very important factor. What alarmed me is Jay's comment about 2-3 feet of water being possible. In the lower portion of our land which gets 2 feet of water in flood, the water is traveling very fast, and has washed out our driveway several times. Even if a house built in this kind of flood plain were raised above the highest flood waters, that wouldn't save the plantings around the house. We've had fences and trees knocked over around our house by flood, and this area isn't even in the main flood channel, this is just runoff over a fairly slight slope. Whether or not the land is suitable for homesteading is entirely dependent on how the flood actually behaves. Basins can tame flood considerably - but you need to be able to install enough of them high enough in the drainage above your house and gardens. The large basin at the top of our property where one of the flood channels enters is regularly overtopped by racing flood water. Water passing slightly downhill of the basin knocks over the neighbors' fence set in concrete. It's easy to underestimate the power of flood water on even a slight slope. Our land is not in a canyon, per se; much of the flood water comes from a fairly gradual slope, yet by the time it gets to our place it has gained tremendous momentum, enough to peel the pavement off the road a few hundred feet downstream.
I'm not trying to be an alarmist, I'm just sharing my first hand knowledge of living in a flood plain. It is a tremendously challenging, though potentially promising, situation. I think a person purchasing this sort of land should have a very hefty bank balance so that major earthworks can be installed as soon as possible, before the house and gardens are in place. We didn't do this and have consequently suffered.
I think a person purchasing this sort of land should have a very hefty bank balance so that major earthworks can be installed as soon as possible, before the house and gardens are in place.
This is key, and I couldn't agree more (even in the absence of a flood plain). The dirt here is so devoid of anything resembling organic matter that earthworks are going to be the primary way we build and protect our soil. Otherwise, it will blow, burn, or wash away.
Yeah the 2-3 feet is high, I've never seen that and can't imagine it even being possible on the flat ground. Some of the washes might get 3' deep. But yeah, dirt work, lots of mulch and ground cover and trees. I will make sure I have enough saved up to get earth work, mulch and planting covered when I put a house on it.
So it looks like the land drops 2' over about 650' headed north, which is about the length of the property. How do you plan swales on such a small slope? The problem is we get rain in large dumps usually.
Yeah I've seen it before but he's talking about 3" of drop between swales(seems like about 40 feet?), looks like roughly twice as much as the land I'm looking at, would be about 85' for 3" drop, is that about how often to put in swales? Every 3" drop?
I'd still put them in, just wondering how many/how close together.
I like Jack's swales so far, I like the way they spread out overflow and reduce erosion. It doesn't take much in this soil to erode into deep canyons, the land further north had a good 5'+ deep canyon from the washes heh. Spreading out the water, slowing it down and planting seems to be the answer. I like how Jack deep mulches his walkways too where Lancaster prefers to hard pack and leave them be. If I can find tree trimmers our something willing to drop off mulch I'll mulch it all and plant weeds and mesquite trees everywhere to build up soil. Surprisingly it looks like this land didn't have many mesquite trees but I'll collect beans from all my friends in town lol. Especially my in laws that have cows grazing in their mesquite, collect some manure to spread with "processed" beans ready to grow.
I'm glad you got the books! I'm wondering if some diversion swales leading into basins might be a strategy to try. Maybe try regular on-contour swales too, but for special plantings, some basins to emulate the Roosevelt swales, which look more like big basins to me.
I finished Lancaster's book Volume 1 last night, starting Volume 2 today.
Did the math and on 10 acres, averaging 10 inches of rainfall a year then 2.7 million gallons of rain falls on the land. I also figured out IF(big if) 1" of rain falls that would be 271,540 gallons(or 36,302 cubic feet) and if I had 5 600' long swales(most of the property width) 6'x3' that would hold 42,390 cubic feet of rain. Or 10 swales at 4'x2'. So either 132' apart or 66'. Roughly, closer to the house would be changed up, and I would want to collect the roof runoff in a cistern for later use. I also researched and the historic averages are all less than .08" of rain per day even during monsoons. In 1878 they had what they consider the 100 year flood and Tucson recorded 5" in 24 hrs so for most days it would be overkill and for a huge storm event they would overflow but unless I get a huge influx of run on from outside the land I would hope the swales would slow down and soak in and disperse water over a larger area so erosion wouldn't be an issue. I will still have to build for the floodplain rules the county has in affect(2' high foundation) but hopefully I will never need it. The more plants I can get in the ground and stuff growing the better the land will be at allowing water to infiltrate. Right now it sheets off because there is a lot of exposed dirt that compacts and sheets water.
It's nice not being in a rush for this though, Even if I do get the land I am probably a year out from actually living there, unless something happens and if I need to rush I can buy a cheap trailer to put out there while we finish the preparation. But it is making me think about everything lol. I'm already planning on running grey water to tree wells and that means only the toilet would need the septic, so do I pay to put in a septic for a toilet or two or go with composting toilets. I will have to check out the composting toilets more in depth. I will have to pay to bring power to the lot, if I am having a big outlay to get power there maybe I just want to invest in solar. I would like the option of being tied to the power grid for 240v because I eventually want a nice welder and maybe a big air compressor. And I was thinking of electric ranges but I really prefer gas, which would mean bringing in a propane tank. Propane can be a hassle but it would also be handy, especially for off grid stuff along with the better(imho) cooking with gas, cheaper heating air and water with gas, etc. I then get into wondering if I want to try solar water heating, I've heard mixed reviews and would need to investigate further.
Then I get to thinking about houses, Originally I wanted a decent sized manufactured home, but I'm getting my wife to come around on a smaller house(smaller double wide or even single wide) and the benefits of that. Then I start thinking of all the customization and wonder if I should just get a "tiny house" maybe even just a shell and frame it in. I have done all the work in construction to put a house together, would just need pro help as needed for inspections and stuff that needs to be certified or could burn the place down with a mistake, etc.
There's a definite underground water along the ditch, can see the track of mesquite and trees growing right along it heh. Lots of tumbleweed or it looks like it. Some looks like possibly ragweed? Can tell it's a flood plain, but I'm not scared. Even had a local stop and talk and warn us when it rains the road is under 3" of water and he calls in to work sometimes because he drives a mini van lol. Dirt needs lots of help and work.
100 degrees in the afternoon and I spooked 2 mule deer out of the thick stuff lol. Really didn't think I would need to worry about deer on this land. Guess it's close enough to the mountains.
There's a culvert running under the road right off the land, like 5 feet before the land starts that had standing water and like 10 dead frogs or toads burnt to a crisp up on the dry land heh. Will need to fix that, standing water no good.
I do not have any experience with this, however I remember watching video of the guy who uses thick wood chip mulch, and he mentioned, that someone in flood area didn't have much problems with this thick wood chip mulch as it can absorb amazing amounts of water. Not sure, how easy is to get wood chips in the desert area though...But possibly worth researching.
Are you planning to irrigate during the dry periods?
If so you can plant some thirstier trees such as hybrid poplars. These grow extremely quickly with a vast root network. They can consume 200 gallons of water a day per mature tree and yet can get by with fairly minimal irrigation when water is scarce (but they are not desert trees and will die if not watered for months).
Plant the thirsty trees in the low points. They will withstand weeks of running or standing water once mature. Plant the less thirsty drought resistant trees on the higher land. When you have an established forest it will buffer the floodwaters. If you are unlucky and get a 100 yr flood event in your first couple of years you might lose a lot of trees, but that should only happen every 100 years or so.
If you will only be visiting occasionally and not able to set up irrigation in your first montths of ownership then plant prickly pears, agaves, aloe veras and the most desert hardy two trees on the planet - leucaena leucocephala and gliricidia sepium. All of these can go 12 mths without water once they are 3 years old or so providing they get some care to start. Dig a big planting hole, fill with a 90/10 sand/compost mix, waterlog it a few days before planting and water well at time of planting. Plant a few weeks before or during the rainy season and they have a good chance of surviving with very little care. If your land is very compacted/rock then use a masonry drill to put some deep drill holes in the bottom of your planting holes.
Once you are onsite and/or have built some soil and shade and/or have some irrigation set up you can plant the members of the next level of drought tolerance eg fig trees, peach trees, certain bamboos, blackberries, yuccas, palo verde, mesquite, certain palm trees....
While you must plan for flood, you will find that lack of water is a bigger problem than flooding. Drought hardiness plant selection, ground cover, soil building is your priority. While establishing your forest you must make sure there is no grazing. Goats will kill your system quickly. Even a few rabbits can devastate tens of small trees. Use appropriate tree protectors. Unless you go 100% cactus/succulent/poisonous plants then you must use trees to build a canopy if you are to make this land work. Nothing else will build the ground cover & root network to provide the water absorption AND drought tolerance needed.