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What's the difference between permaculture-ish water retention and water diversion for agriculture?  RSS feed

 
Posts: 7
Location: California, Redwood forest valley, 40°N, 8mi from ocean, elev 1500ft, zone 9a
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I'm trying to understand the difference between permaculture water retention, e.g. making swales to keep rainwater around rather than letting it run off into streams to the ocean, vs the much bemoaned waste of water in agriculture.

For example, I've heard many times that the pot farms in our region use up too much water so streams are going dry, e.g:
https://www.npr.org/sections/thesalt/2014/01/08/260788863/californias-pot-farms-could-leave-salmon-runs-truly-smoked

I'm only interested in the water usage aspect -- of course the pesticides and fertilizers are bad.  And of course, clearing forest to grow crops is going to affect the climate and probably result in less rain, that's also a separate issue.

If I dig a swale and divert a lot of rainwater into it so it slowly seeps through our garden for the fruit trees to use, rather than running off directly to the creek, what's the difference between what I'm doing and what these other farms are doing?  Is it just that the pot farms are throwing water up into the air so there's a lot lost to evaporation?  Or how is this water disappearing?  I would expect water used to irrigate marijuana to eventually percolate down to the creek the same way it would in our permaculture garden.  

I want to be like the beaver, slowing down the water so it sticks around and makes habitat of all sorts, and I want to understand how I'm not doing something harmful.
 
pollinator
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A half water cycle is when water doesnt get absorbed into the ground. It runs off carrying contaminants, erosion, evaporating, flooding, etc etc

Full cycle goes into the ground.  It is cleaned, recharges aquifers, hydrates the soil, creates springs, etc

Zach Weiss had a great explanation. Ill post a youtube. Probably the most influential video i have watched.
 
wayne fajkus
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Watch "Zach Weiss   Water Retention Landscapes   LSSM" on YouTube


 
Philip McGarvey
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Location: California, Redwood forest valley, 40°N, 8mi from ocean, elev 1500ft, zone 9a
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wayne fajkus wrote:Watch "Zach Weiss   Water Retention Landscapes   LSSM" on YouTube
https://youtu.be/Kl4KSoBRQ4M



Just watched that, and also read this on the half/full cycle:
https://treeyopermacultureedu.wordpress.com/chapter-7-water/hydrological-cycle-half-and-full/

I was already familiar with this stuff, I guess my question was more "what are these other farms doing that's causing the problem", and my guess is it's something like this:

- they're clearing forest which raises ground temperature so water runs off quicker
- they're spraying some amount of water in the air so it evaporates faster and never gets into the ground
- they're probably making their irrigation water overflow directly to creeks rather than sink into the ground

The key bit I was wondering about was how are they preventing the water from reaching the streams, and I think the answer is that they're not.  The streams are drying up because when the rain does come down, it flows out to the streams even faster than it would have with a healthy ecosystem, so the streams run faster in the rainy season and then run dry in the summer.  
 
gardener
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Location: Olympia, WA - Zone 8a/b
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Philip McGarvey wrote:

wayne fajkus wrote:Watch "Zach Weiss   Water Retention Landscapes   LSSM" on YouTube
https://youtu.be/Kl4KSoBRQ4M



Just watched that, and also read this on the half/full cycle:
https://treeyopermacultureedu.wordpress.com/chapter-7-water/hydrological-cycle-half-and-full/

I was already familiar with this stuff, I guess my question was more "what are these other farms doing that's causing the problem", and my guess is it's something like this:

- they're clearing forest which raises ground temperature so water runs off quicker
- they're spraying some amount of water in the air so it evaporates faster and never gets into the ground
- they're probably making their irrigation water overflow directly to creeks rather than letting it all to sink into the ground

The key bit I was wondering about was how are they preventing the water from reaching the streams, and I think the answer is that they're not.  The streams are drying up because when the rain does come down, it flows out to the streams even faster than it would have with a healthy ecosystem, so the streams run faster in the rainy season and then run dry in the summer.  



I started my career as a hydrologist for the USGS - it was my job to go out and measure water flow at gauge stations all over Washington State. If you look at water flow data from stations on streams where there is a lot of forestry or farming you get what is called flashy responses to storm and snow melt events. The flow peaks super fast and then drops super fast.

In natural systems (at least up here in temperate lands - deserts can get flash floods even in a natural state) and in good permaculture designed systems like what Zach Weiss is designing the water is slowed down and allowed to infiltrate into the soils. Ideally, it is also spread out so the water has a much larger surface area of land to infiltrate into. Ground water moves much slower than surface water.

The result is instead of a big spike and then a drop (flashy) you get a nice broad rolling hill - you can actually have more water moving through the system but the peak flow will be less than in the flashy system. The good system will maintain an average higher flow for a longer period of time after a rain or snow melt event than a flashy system.

Flashy systems make drought situations worse since the water is gone and out of the system much faster than in a natural system or well designed system. Beavers used to do an amazing job at making systems less flashy when they were more common in the western United States.

Attached is an example of a flashy system near Spokane Washington that I used to measure. It flows through a very heavily farmed area and has a lot of sediment and temperature issues that is caused by the flashy nature of the system. The graph covers 2 water years - October through the end of the following September is 1 water year. That time period captures the full cycle of any river which is why water years are used in hydrology instead of regular years.
flashy-water-system.gif
[Thumbnail for flashy-water-system.gif]
Flashy water system - 2 water years
 
pollinator
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Location: Victoria BC
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Daron, nice post!

I think there is another side of it as well: at least some places, again water is being sourced directly from streams, or groundwater destined for streams, during the dry season; farms are not storing enough/any themselves in the rainy season. Then they are blasting it into the air with huge sprinklers, and tada... dry streams.

I nearly bought a property directly downstream from a dairy farm. Sizable for the area, but not by US standards.

I ended up living nearby for over a year, and drove past many times in all seasons.

This dairy farm had a dugout reservoir, fed from flowing groundwater at one edge of the property. A channelized stream came from this, through the property I was outbid on, and became a wild stream on the far side of that one.

The reservoir was way too small. They had a big excavator, but I never saw them working on that issue. They would grow corn, and hay, for the mostly-confined cows. They irrigated in the day with big guns, in 35C heat. The reservoir would run dry well before the rainy season; accordingly, so would the channelized stream downstream of it. They would let thedugout recharge a bit, then run it dry again, blasting out all incoming water onto their fields, much lost to evaporation, before the stream could get any.

They had the water license... no need to conserve in their minds I suppose.

-----

Edit: I incorrectly said 'most' lost to evaporation, 'much' is accurate. Average efficiency of irrigation guns appears to be 60-75 percent after evaporation, drift, runoff.

I still do not see a good reason to run their guns in the day vs night.

I *really* do not see a good reason to use an overly small reservoir and drain it completely, leading to the loss of eater in the stream. You could fill a truly enormous reservoir with the winter rains here...
 
gardener
Posts: 3737
Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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Water does not disappear, after it is blasted into the air with huge sprinklers. The vast majority of it falls to earth, and seeps into the ground. Some small amount evaporates. It returns to the water cycle, and settles out of the atmosphere as dew, snow, rain, etc...  
 
Posts: 412
Location: Western Canadian mtn valley, zone 6b, 750mm (30") precip
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Hi.  Joseph also posted in this thread concerning irrigation systems:  https://permies.com/t/75031/drip-sprinkler

It's be great, actually, if people would resume posting on the topic in that thread, too.  These topics are sort of related.
 
pollinator
Posts: 2130
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
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Trad farmer (with river)
-pumps up 3x amount of water
-Store water in a tank/ open pond
-irrigates plants with water via pump/sprinkler
-plant are okay
- Water Input=3x, Water Seepage+Runoff to river =1, Trees+Evap =2, River is down by 2

Permie (with river)
-pumps up 1x amount of water
-store runoff in swale
-irrigates plants with swale, and swale seepage
-plants are happy, with mulch, nutrient rich water/soil life, protective biota
- Water Input=1x, Water Seepage+Runoff to river =.5, Trees+Evap =.5, River is down 0.5
-----------------------------------------------------------------------
 
S Bengi
pollinator
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Trad Farmer (natural rain + well/river)
-Build huge roof to capture rainfall
-Store all rainfall in a tank

-Okay more like it fell on the field and and got used up by plants
- Plants still need water about to die
-pumps up 2x amount of water
-Store water in a tank
-irrigates plants via pump/sprinkler
- Water Input=3x, Water Seepage+Runoff to river =1, Trees+Evap =2, River is down by 1

Permie (with natural rain)
-Use the ground to capture runoff
-store runoff in swale
-irrigates plants with swale, and swale seepage
-plants are happy
- Water Input=1x, Water Seepage+Runoff to river =.5, Trees+Evap =.5, River is UP by 0.5
- The river also doesn't have flash flood and actually have water entering in the dry season vs negative for trad
-----------------------------------------------------------------------
 
Joseph Lofthouse
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Posts: 3737
Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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In my ecosystem:

Water runs via gravity to my fields.
Zero water runs off my fields, neither from rain nor irrigation.
Water that percolates through the soil re-emerges from springs 1/4 to 1 mile away from my fields.
Water that evaporates from my fields settles as dew, snow, or rain, in the nearby mountains, and runs back down to my fields.
Repeat for the next village downhill.

 
S Bengi
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You are like a hybrid not a perfect fit for the "permie" mold whatever that is, but also 100% not a commercial farmer with GMO, roundup, etc.

It is a not a 1 or a 0, but a continuum, with no 1 single answer, much less one that works for all location.  

I know that I simplified stuff by just saying getting water with dissolved mineral into root = SWALE
but really SWALE = optimized landrace, all types of earthworks, mulch, subsoil-tillage, hummus/carbon, soil life, rockdust, sectional polyculture, etc, etc. and all the wonderful tricks that you have up your sleeve.
 
Joel Bercardin
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Location: Western Canadian mtn valley, zone 6b, 750mm (30") precip
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S Bengi wrote:Trad Farmer (natural rain + well/river)
-Build huge roof to capture rainfall
-Store all rainfall in a tank

-Okay more like it fell on the field and and got used up by plants
- Plants still need water about to die
-pumps up 2x amount of water
-Store water in a tank
-irrigates plants via pump/sprinkler
- Water Input=3x, Water Seepage+Runoff to river =1, Trees+Evap =2, River is down by 1

Permie (with natural rain)
-Use the ground to capture runoff
-store runoff in swale
-irrigates plants with swale, and swale seepage
-plants are happy
- Water Input=1x, Water Seepage+Runoff to river =.5, Trees+Evap =.5, River is UP by 0.5
- The river also doesn't have flash flood and actually have water entering in the dry season vs negative for trad
-----------------------------------------------------------------------


S Bengi, I'd think the crops nearest to the swale might be much better watered by the water from the swale than the crops further away.  If this is not the case, please tell me why it isn't.

Of course, with mixed-plant cropping, you could plant the more water-loving/water-needy plants nearer to the swale, and ones that will require less further from it.

Also, I wonder about your formula that the same soil-planted crops can be grown with just 1/3 the amount of water as the system you designate as traditional farming.  Who has tested the systems?  How many of each system did they test?  Were all other factors comparable? etc.
 
I do some of my very best work in water. Like this tiny ad:
Food Forest Card Game - Game Forum
https://permies.com/t/61704/Food-Forest-Card-Game-Game
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