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Global question about Swales...  RSS feed

 
Lee Real
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A friend asked me a question. Is if everyone started to use Swales, will it run out of water elsewhere, such as in rivers?
 
John Elliott
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In the long run, no. One of the principles in climate modeling is that global warming makes for more water in the atmosphere, leading to heavier rains (although they may be more sporadic). So there is more need to catch all this precipitation before it runs off into the oceans.

If everyone built catchments and swales now, yes, it would take some time for them to fill up and in the interim, rivers might "run low", but in time, the water cycle will return to an equilibrium state.
 
Dale Hodgins
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In many areas, spring melt water quickly rushes to the rivers, turning them into a raging torrent for a short time. It's like flushing the toilet and then nothing. The river sits, barely flowing in summer. Other areas experience huge rain events followed by long dry periods. Again, the abundance is lost, causing erosion in the process. If we all got a consistent 1/4 inch of rain every 2 days throughout the growing season, nobody would need swales. Nature gives us water a little or a lot at a time and not always when needed. Swales are a convenient storage mechanism. Some water still makes it to the river, but not in a huge deluge immediately after rain or a thaw.
 
R Scott
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Swales SLOW water, not STOP it.

They are proven (when applied correctly) to take surges (reduce flooding) and then release over time (keep it flowing instead of going dry). They are shock absorbers.

If you put a swales everywhere all at once, they would reduce river flow temporarily until they charged--the the rivers would flow cleaner and more consistently.
 
Brett Andrzejewski
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I agree with John. The research I have done shows that the water levels may go down in the short term but will return to a normal level afterwards. It has a long term effect of keeping ephemeral streams (seasonal streams and creeks) running longer!

The problem comes from the emotional reaction of "You put in a swale and now I saw my water levels drop (well, stream, creek)!" Seeing this means they are evil and you are stealing my water.

VS

The logical observation of the land becomes more hydrated. Water cohesion allows more water to be stored. The water then slowly reaches the bedrock and slowly travels to the stream and is slowly released into the stream that allow for a buffer effect.


Now, that I think about it, I have heard the same mentality applied to trees. "Trees drink up all the water that I need from my crops". People know that trees need water and believe they drink up all the water. Yet, trees have worked for millions of years to get the ground to hold more water, trees will pull water up from down deep during the night and hydrate the soil around them, prevent run-off, and buffer the loss of water.
 
nathan luedtke
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I'm thinking of this in terms of the "Water Cycle." Here's my mental model of how it would go down:

We suppose that overnight, the entire Earth has been fully swaled, ponded, and generally turned into a water retention landscape. Thanks, Mysterious Permaculture Aliens.

The next day, stream and river flows drop dramatically. Water can't just flow downhill anymore!

The sun continues the cycle of evaporation at a constant rate (or increasing, depending on climate change). Rain events continue as before- but now there are structures to capture and contain all rain.

Because more fresh water is now being held on the landscape, there is more total fresh water in the system, meaning even more potential evaporation is happening. (ponds in the Sahara mean that more overall land surface can produce evaporation)

Local climates are now more humid and stable. Over the first few weeks, streams and rivers are at alarmingly low levels. Hydro plants go offline so that their dams dont go completely dry. People start to panic. Damn those Mysterious Permaculture Aliens!

The PRI, and Permies.com, puts out a massive information packet teaching people how to deal with the new situation. The world is flabbergasted by Paul. Global interest in Permaculture, spiked by the MPAs, takes off.

Maybe there would be a little difference in that because more freshwater is cycling in the system, the ocean would get a tiny bit saltier? Ocean swimmers start setting new records because buoyancy.

After the first year, streams start flowing more. The world is getting hydrated again. Many ecosystems (especially desert-adapted ones) start changing dramatically- new niches are opening and opportunistic species exploit those niches aggressively. The Nature Conservancy makes their largest purchase yet of herbicide.

The agriculture lobby holds the US government hostage over the fact that all their fields are now bisected by water harvesting earthworks. They want to take retaliatory action at the MPAs.

Some farmers bulldoze their earthworks back down to flat fields. Must be efficient. They go out of business within 3 years.

The next year, streams are up to their previous levels. Everyone breathes a sigh of relief and calms down a bit.

Each year thereafter for four or five years, stream levels inch up more and more. After seven or so years, everything is nice and damp, everything is green, the climate has moderated, Permaculture Paradise. The NSA is still tapping our phones.

Basically, everything looks like Naboo.






This started off as a serious thought experiment. Sometimes I get carried away.
 
Dale Hodgins
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You don't have to go back too far historically or to include aliens to imagine a well hydrated landscape. The American west was much more hydrated and less prone to drought when beavers were in charge of water management. The tall prairie grassland shaded the soil for maximum percolation and minimal erosion.
 
nathan luedtke
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Dale: BEAVERS ARE ALIENS
 
Brett Andrzejewski
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nathan luedtke wrote:Dale: BEAVERS ARE ALIENS


I was wondering why they were trying to abduct me...
 
Nicholas Mason
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Its true, beavers were great for the water cycle. Adding swales recharges the land and the aquifer. Back before modern civilization, and heavy logging we had a lot more springs and creeks, wetland, and ponds. They have all dried up now. But it shows us that with a hydrated landscape everyone gets more water.
 
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