Water harvesting

I'm beginning a water-harvesting project for a 0.6-acre field that will be planted with a mix of annuals and perennials, and I'm looking for relevant sources of information.

Most of the books I have read (e.g., the excellent Water Harvesting for Drylands and Beyond) focus on arid climates with deep soil and limited annual rainfall. Puddling and runoff are the result of mismanagement, and the advice to infiltrate ASAP is sound.

I by contrast am in a cold humid climate (Maine), and I have shallow soil that is saturated during the winter and alternately parched and saturated during the growing season. I don't have a pond or access to a stream, so I can't just irrigate whenever it gets dry.

I am muddling my way to a solution, I hope. But I can't be the first person to have encountered this situation, and I am wondering whether anyone knows of a book that focuses on water harvesting (both in and above ground) in humid climates specifically.

Many thanks,
Andrew

In your environment you might find that collection is a more viable solution to your water needs.

This will depend a lot on available structures which can be used for rain water collection.
If you have no structures on this land, then you have to weigh the feasibility of installing some swales (usually you need to have a bit of grade to the land for this to work really well), installing one or more ponds or just improving the ability of the soil there to adsorb the rainfall.
Since you mention dry periods (similar to what we have in Arkansas, monsoon like events twice a year with drought conditions between) it will be a series of trade offs to come up with a good workable plan in the event there are no structures to use for collection of rain water.

In our case we are installing some swales, some terracing and we use water collection from our building roofs.
The swales are used for providing water to the terraces and the pumpkins, sunflowers, barley, oats, artichokes, etc. that we grow in those spaces.
For containing the water collected we use 275 gallon "Totes" which we can purchase for around 60 dollars each from a few sources.
Our system continues to grow as we build more housing for animals, we install collectors connected to barrels so that water collected say from the hog houses is used for the water source for the hogs, same for poultry.
We collect the rain water from our house roof for use in the gardens and orchards, this particular system keeps getting totes added to it as we can buy them, our goal is to build this particular system so we can hold around 5000 gallons for growing food plants.

Depending upon your needs these totes can be linked so that all fill from the guttering and associated piping and all can be drained from a second set of piping. We get most of our animal and garden water from our collection systems.
You can also use food grade plastic barrels (these can be found in 55 gal. up to 75 gal. sizes) again linking them if need be or you could use a combination.
One other alternative is the traditional "cistern" as has been used from antiquity to the present for storage of collected water.

A little more detail will allow folks to give you best fit advice and suggestions.

I use 55 gal food grade plastic drums that I get from a local brewery for $5.00 each. It is very easy and inexpensive to build a water catchment system if, as Bryant said, you have a structure available to harvest the rainwater.

I have a roof and several wells I can tap for spot watering, but the water they can provide is small compared to the irrigation needs (conventionally sized) of a half-acre vegetable field. My roof, for example, can provide maybe 375 cu ft of water in an average month; but over the course of a month-long drought (like the one we had last summer), giving a half-acre field an inch of water per week would require ~8,000 cu ft.

So I am more focused on (1) reducing water use by terracing the 10% slope, mulching, building soil, etc., and (2) directing runoff from a 3-5 acre uphill catchment area into the field by gravity flow. Does anyone know of a book that covers things like that from a cold-humid perspective? Or, for that matter, one that explains why I should just give up, dig a pond, and buy a big pump?

If you use or can obtain large quantities of organic material for your gardens, consider storing them just uphill of areas that need more stable water. I have a large pile of wood chips waiting for use in my gardens. Even after six months of very dry weather the downhill side of this pile is still moist when I dig into it.

If you don't have room for a 6 foot deep pile, maybe thick layers of mulch in the walkways? They could both wick excess water up from the garden soils and then slowly release it during drier weather. I'm just guessing that in Maine you need to have bare soil for early spring heating, so wouldn't benefit as much from the year round deep mulch I use in the garden.

This might be faster and cheaper to implement than a rain catchment system. It works very well a part of a combined system also. We have been able to empty our cistern, for maintenance, into our garden and had all the water absorbed into mulch rather than washing off our property. Eventually we plan to get at least three more cisterns, and expect the combined resources to be enough to carry our garden through even drought years.

I certainly will be mulching, although for the reason you mentioned it won't be all beds all the time. Good idea to pre-moisten it, though. There are some wet spots I can pile it in, and then move it from there to the garden as needed.

Ben Falk has done some pretty amazing water harvesting stuff on his property in your region with similar soil/climate situations. He has a few very well presented videos on youtube that you can search. He also has a book , and a website (same link).

weigh the feasibility of installing some swales (usually you need to have a bit of grade to the land for this to work really well), installing one or more ponds or just improving the ability of the soil there to adsorb the rainfall.

I second the nominations fro swales and ponds in your situation, particularly if you have a run-off situation. To paraphrase Art Ludwig, the guru of many for all your water harvesting needs: The best place to store water is in your soil or underground. Swales do not have to be huge to be effective, and might be a good use of personal energy to eliminate runoff and charge both your subsoils and rock strata. Ponds can be any shallow catchment, they do not have to be dug by an excavator, or backhoe to effectively charge your ground water system; the choice of where you place them is more important in many cases than their size.

I also very much second Cassie's mulch idea.

I use heavy mulches [predominantly spoiled hay from local farms] in my area (which has a similar climate to yours, but a bit colder), and have made numerous advantageous observations with it's water retention abilities. Heavy mulch eliminates evaporation, catches dew (when your daily/nightly temp fluctuates), traps rain, breaks rain's impact, creates a fungal interface at soil level, increases earthworm habitat. All of these will help in charging your soil/substrate with long term water storage.

My climate certainly has the wet winters/dry summers thing going on, though our drought last year was a lot more than a month. Irrigation is key for many crops here, even in 'normal' years.

What I'm seeing done around here lately is that swales are installed, but there is the expectation that there will be far too much water for them to absorb, so they are designed to be able to flow a lot of water into either drainage or storage when filled. Sometimes a very gentle slope is added to facilitate this second portion of their task. (Swales can be laid out using keyline design, in which case they would have a very slight slope to move water towards the ridges; see link in my later post.)

A nice deep pond to irrigate from would almost certainly be the cheapest form of water storage on a per gallon basis... unless the ground does not allow for one to be dug on your land, that is. No need to fill it from your rooftop if the ground is that wet; it should readily fill up if the ground around it is saturated, with the added benefit of drying out the ground around it so that you can work it earlier in the spring. Swales feeding it when full would certainly help too, especially with getting a quick boost to storage levels if you get occasional torrential summer rain.

You'd also get the benefits of the nice microclimates around such a pond...

Directing runoff from uphill is great, but it's still going to be pretty dry a month after the last rain. Swales to absorb and direct to your pond... and you might even find that some of that uphill water is flowing underground right through where your pond should be placed... For that matter, perhaps there is sufficient catchment and space to put the pond upslope enough that you can gravity feed to the field?


I haven't read Ben Falk's book, but I'd second Roberto's recommendation based on his videos.

Some really good ideas by Dillon in his post above.

On this one though, I'd say it's unnecessary, and I would heed it with caution:

Sometimes a very gentle slope is added to facilitate this second portion of their task.

Perhaps that is the case for some people to do this but I wouldn't recommend this. If a swale has a proper sill or sills (an area left at ground level... whereas the swale mound is above that for the vast majority of the swale), and these sills are adequate for storm surges, then the swale can drain via a stone lined spillway, or vegetated surface flow, into a pond, another swale, or other catchment, from the sill area(s). Any slope that is added to a swale, gentle or otherwise, will turn it into a ditch in high rainfall situations, and this will cause unnecessary/unwanted erosion/degradation to your system. The swale, by definition, is an on-contour system. Not sloped. It is designed (almost exclusively) to be a long thin 'pond' for infiltration.

One of Falk's videos shows his swales 'flowing' over sills to get caught in the next swale. There are some other 'swales in heavy rain situations' youtube videos by other people that show how it works as well, though not as good as Falk's video from what I've seen. Anyway, that's my understanding; I might be missing something. I've just never heard of swales with slopes, unless you are trying to drain land.

I haven't read Falk's book either, but considering what I've watched of his on youtube, I'd predict that there are some really useful descriptions in his book on water catchment strategies in your region.

Roberto Pokachinni wrote:
On this one though, I'd say it's unnecessary, and I would heed it with caution:

Sometimes a very gentle slope is added to facilitate this second portion of their task.

On re-reading my post I have mis-characterized the purpose of the slope. Amended that post for clarity; thanks for making me take a second look!

The designer was referencing this article, which is about keyline swales; the aim(like with all keyline designs) is to concentrate water at the ridges, hence the slope. http://permaculturenews.org/2009/11/30/keyline-swales-a-geoff-lawtondarren-doherty-hybrid/

That article mentions a slope of 1:500.

While I recall that the overflow was at a low point in one example, I can't really see that it would actually matter, in practice, given that the overflow won't be flowing until the swale is full. The slope is so slight that the swale will be full of standing water for the entire length before the overflow sill is reached, despite the gentle slope in the swale bottom. You could put the sill anywhere. (This might not be true for very long swales in some types of terrain... further checking would be needed)

As with 'normal' swales, the sill needs to be just right.

Hope that makes more sense now...

Yes, it does. I was assuming that the swales would be built off contour to create the slope, not that the slope would be created in the base of the dugout part of the swale. Thanks for the more thorough description. I'll check the link later today, after work, so that I understand even further.