Swales and Basins in Action!

img_0685This week here in Fallbrook, CA, at Finch Frolic Garden we received almost three inches of rain in 18 hours. Our storm pattern is changing so that there are fewer rain events, but when it rains, it really rains. img_0688For many this was a flood. Precious rainwater is channeled away from properties and into the street. In permaculture gardens the water is harvested in the earth with simple earthworks such as swales (level-bottomed ditches) and rain catchment basins.

Visitors have often expressed their desire to see the earthworks in action, so I took my camera out into the food forest. img_0691That was when the rain gauge was at about two and three quarters, with more to come. (I wanted to photograph the garden after the storm had passed but my camera refused to turn on due to the indignity of having been wet. A couple of nights in a bag of rice did it wonders.)img_0692

Please excuse the unsteady camerawork, and my oilskin sleeve and dripping hand making cameo appearances in the film. I was using my hand to shield the lens from the rain.

Creating Rain with Canopy

Even if we don’t receive a lot of rain in drylands, we might have fog, sprinkles and other degrees of ambient moisture. This moisture can burn off with reflected heat from hard-packed earth, from gravel and hardscape, and from buildings.  It is too irregular and thin to make the use of mist nets feasible.  However, a much better way to collect that moisture and turn it into rain is the method nature uses: trees.  The layers of a plant guild are designed to capture, soften and sink rainwater, so why not just let them do it? Many trees are dying due to heat, low water table, lack of rainfall and dry air. Replacing them with native and drought-tolerant trees is essential to help put the brakes on desertification.

Please take five minutes, follow this link and listen and have a walk with me into Finch Frolic Garden as this 5-year-old canopy collects moisture and turns it into rain:

Plant a tree!

Irrigation For Drylands: Conclusion

One-inch PVC runs from the valve.

One-inch PVC runs from the valve.

This is the last of the series of posts on irrigation, and I’d like to briefly address the issues of water pressure and valves.  As I’ve said in a past post, if you don’t know about these things then hire someone who is an irrigation specialist (not just someone who says he’s put together irrigation before… they are guessing!).  That specialist will obtain for you the right sized valves, the right irrigation timer, and monitor the water pressure so that your sprinkler heads won’t blow off and pipes break.

The one-inch pipe is then reduced to 3/4" pipe at the first T, close to the first sprayer.

The one-inch pipe is then reduced to 3/4″ pipe at the first T, close to the first sprayer.

For pipe, don’t use small 1/2″ pipe for large jobs.  Bigger – to a point- is better.  Smaller pipe doesn’t mean higher pressure.  It reduces the volume of water going to the sprinklers.  The smaller pipe creates more pressure loss due to friction and turbulence as the water flows through it.  We took the advice of our irrigation specialist and ran 1″ pipe from the valves to the first sprinkler, and reduced it to 3/4″ pipe, then reduced for the 1/2″ risers.

Further reducing 3/4" to the 1/2" sprinkler configuration.

Further reducing 3/4″ to the 1/2″ sprinkler configuration.

Most sprinkler systems need a water pressure of between 30 – 50 psi.  Drip systems need less, around 20 psi.  Too high or too low a water pressure will adversely affect your system.  If you attach a water pressure gauge to a spigot you can see what your pressure is.  If it is very high, you will want to check the indoor pressure as well because too high a pressure can mean pipe damage and leaks, and no one wants wet walls.  You can use a pressure regulator on your line to reduce the water pressure for your irrigation.

How many sprinklers you can put on a valve depends upon several factors, but mainly the flow rate, or how much water is flowing through the pipes at one time. Sprinklers have an output rate so you can do the calculations on how many you can put on a line.  Flow rates are measured either in gallons per hour or gallons per minute, with gpm the most common for householders.  Drip systems are less concerned with flow rate.  We ended up adding valves to our system because we had so many sprinklers.

When installing your system, be sure to add a ball valve (rather than a cheap gate valve) close to your water source so that if you have to work on your system you can shut it off; otherwise you’ll have to shut off the main to your outside water.  If you have a large system, installing ball valves along the line to isolate different areas will help down the road if you need to troubleshoot.  Having hose bibs along the line are very nice, too.

There is a lot to learn about irrigation valves – using globe valves with an expensive back-flow preventer or using anti-siphon valves that must be above ground and above the closest sprinkler head.  I’m not an expert, but there is expert advice on valves hereIMG_9924

Another thing to consider is your electrical line.  If you have valves, you must run electrical line to them (at this writing, solar valves are not that dependable for the long run).  Electrical line must also run from your irrigation clock to your electrical source at your house.  Usually electrical line is buried.  Please spend the little extra money and have the electrical pulled through conduit first, rather than direct burial!  Having loose wires buried in your yard is a recipe for disaster.  I know this.  I asked for conduit with the original system, and the wire was directly buried before I could protest.  Sure enough, two years in and a valve wouldn’t turn on.  The problem was with the wire… but where?  How to dig it all up without nicking any of the lines?  Impossible.  So until this project two of my valves had to be tied together and both stations running simultaneously, which really stunted the water pressure and was a real headache.  This time the conduit is run above ground along with the PVC pipe, which will be covered with mulch, and also along the top of my chain-link fence up to my house. If there are any problems, the conduit comes apart every ten feet and wires can be checked or replaced.  Pulling electrical wire through conduit is not for the fainthearted; I developed new muscles and callouses working on that, but it was worth it.

Skipping ahead, your irrigation project is finished and your landscape planted.  Be sure to take the time to update your plan so that it is an ‘as-built’, reflecting any changes you’ve made.  This is an invaluable document not only for your own use, but for any future owners of your property or workers who might need that information.  Use a rough plan of your yard and identify each valve and the area the valve covers in different colors.  If you want to draw in every sprinkler head, that is fine.  On large projects that isn’t practical, so just use zones.  Take a waterproof marker and write the valve numbers on the valves themselves, so that you won’t become confused in the field.

Be sure to run each valve during the daytime while you inspect the sprinklers for clogging or broken heads.  A lot can go wrong during the night when most systems run, and you won’t know it until you get the water bill or your plants start to die.

You may want to put in the wire for additional valves that may be added in the future.  Making double  valve stub-outs and only using one is far easier than pulling new electrical if you find that you need to add a valve.  

So don’t think that irrigation is a simple endeavor, and begin to glue miles of 1/2″ pipe together with 2 – 3′ risers that shoot water up embankments.  This is a waste of money, plastic, water and plants.  Put as much thought into your system as you put into the design of plants, and your system will give you little trouble in years to come.

Oh, and remember to shut your system off when it rains!

EPSON MFP image You can read Options, Part 1 of this series here, Part 2 Evaluating Your System here, and Designing Your System Part 3 here .

Irrigation for Drylands, Part 3: Designing Your System

Google Maps view of property lines.

Google Maps view of property lines.

Before you start buying pipe, make your design.  If you are new to the property, evaluate the plants and features that exist and decide if you really want them or not.  Use the ‘three positives’ rule in permaculture: everything in your yard should give you at least three positive things.  For instance, you have a eucalyptus tree.  It gives great shade, it is a great roost for larger birds which keep down your mice and rats, it drops lots of leaves for  mulch, etc.  On the ‘negative’ side, they are really thirsty and they send their roots out in search of water.  They will go to the nearest irrigation and drink from there, robbing water from the tree you are trying to water.  They are also allelopathic, meaning that they produce a substance that discourages many other plants from growing, or growing successfully, under or near them.  Their root mass is so thick close to the surface that very few plants can survive.  If planted in the wrong spot they will block views, hang over the house, drop those leaves, peels of bark and depending upon the species, heavy branches, where you don’t want them, get into overhead wires or underground leach lines, etc. They don’t make good firewood or building material, and are highly flammable. How does the tree weigh in?  Usually eucalyptus are all negatives in my book.  Only if they are providing the only shade and bird perches for a property are they useful.  Even then I recommend pollarding them (reducing their height) and trying to ‘nursery in’ other better trees to take their place.  Cut trees then should be buried, as in hugelkultur.   So evaluate what you have using the three positives rule and don’t be too sentimental if you don’t like something.  Do you like them?  If not, cut them and bury them to fertilize plants that will serve you, and yes, aesthetics is very much a plus.  If you love a particular plant, then if its possible, plant it.

If you have a property that is a blank slate, your irrigation diagram will follow your plant design.  If you have an existing landscape, as I had, you need to map out where all the trees and groupings of plants are, what their water needs are and keep in mind the way water runs past these plants when you do.  Use Google Maps.  Type in your address, find your home and zero in on it until you can clearly see the boundries of your property.

At the bottom right hand corner of the screen is the key that show how many feet are in a measurement. This line may not always equal an inch, so measure it!

At the bottom right hand corner of the screen is the key that show how many feet are in a measurement. This line may not always equal an inch, so measure it!

At the lower right Google shows you a key for distance.  There is a line with a number above it.  This shows you how many feet are represented by that length.  Don’t assume that the line is one inch!  The line will adjust, so put a ruler up to the screen and measure it.  I zoom out until the line is an inch long, and take that number; its just easier to compute distances using an inch rather than a fraction.  You can print that diagram of your property line, which will show you which way your house sits on the property.

Satellite view of Finch Frolic Garden. This helps to map groupings of vegetation.

Satellite view of Finch Frolic Garden. This helps to map groupings of vegetation.

I have a PC, so I press the PrntScr (print screen) key, paste it onto a paint.net screen, crop off the extra bits and print that.  Now you have something to work with.  I double or triple the size of the drawing onto a larger sheet; this can be done easily with a ruler, using the printed sheet to guide your angles.

A projected irrigation plan for Finch Frolic Garden. What you actually put in may differ.

A projected irrigation plan for Finch Frolic Garden. What you actually put in may differ.

Make a couple of copies of this template, and then use one to start drawing.

When you have the plants down on paper, then start with the irrigation.  Determine where your water main is, and where any valves and hose bibs are around your house.  If you only have domestic water to choose from, you’ll be coming from a domestic line.

Fifteen to twenty sprayers are good per valve.  I’m not talking about high-pressure nozzles that shoot water all over the place; these you want to eliminate. Most of that water is evaporated.

The sprinklers that we installed have a spray of up to 4 feet, and can be reduced down to a drizzle.

These are what we installed here: IMG_0080


The 3/4″ T was glued in facing sideways rather than straight up.  A black Street 90 and a white Street 90 were screwed into the T, firmly but with enough leeway to turn if pushed.  Black ones don’t need pipe tape because they are soft and self-seal.   The risers (nipples) are 6″, and were taped at both ends before screwing into the Street 90.  (You don’t put the heads on yet because you’ll want to ‘blow’ out your system with water to clean the pipes beforehand. )

These risers can bend!

These risers can bend!

With this configuration the risers are resistant to damage from being kicked, from having 100-lb. tortoises crawling over them, etc.

Gamera enjoying the movable sprinklers.

Gamera enjoying the movable sprinklers.

They can be moved in all directions so that you can deliver water closer to small rooted new plants, then move them away as the root ball grows.  If you have the assembly ready when you glue in the T, then you won’t have to struggle to screw it on.  Ends will have a slip/thread elbow glued sideways with the same assembly.

There are lots of sprinkler heads out there.  These sprayers have threaded ends rather than barbed, so that they stay in place rather than be blown off.  These are 360 degree sprayers; you can obtain threaded sprayers for 180 and 90 degree, and probably other configurations as well.

A 180 degree head. Notice all the white? That is mineral deposit, and the sprinkler has run only about 10 -15 times.

A 180 degree head. Notice all the white? That is mineral deposit, and the sprinkler has run only about 10 -15 times.

Don’t forget the filter.  A filter in every head saves you a lot of grief with plugged heads and poor irrigation down the line.  They are easy to clean.

Next post: Concluding the project.

You can read Part 1 Options here, Part 2 Evaluating Your System here, and Part 4 Conclusion here.