Review…
Rainwater—how to harvest and store it
I’m republishing an article I wrote in 2009 because the ideas in the books are still relevant. They are about harvesting and storing rainwater and the earthworks to do that at the domestic scale. They provide the information to implement the permaculture design principle about valuing and making use of renewable resources. The books , Volume 1 and 2, were supplied by the Australian importer for purposes of review.
Russ Grayson | On July 10, 2009
I HAD A DISTINGUISHED VISITOR staying at my little shack this week, and I’ve had the good fortune to read the booklet and watch the video CD she left me. It’s all about her Blue Mountains house, how she retrofitted it, how she developed her small garden and how she makes the most of the water falling on her urban block. But, it’s not that retrofit video with its home-spun, permaculture design know-how that is the focus of this review. It’s water.
I saw Rosemary Morrow’s garden when it was in construction, and looked curiously at what seemed to be a rather large hole that she dug. As I watched her video, I came to understand the logic of that hole and its role in the curious earth-shaping exercise she was undertaking. As it turns out, Rosemary’s backyard earthworks were all about harvesting, detaining and infiltrating into the soil the rainfall that comes onto and flows through her site. Her video and booklet is the focus of a different article but they are pertinent to the book I want to write about here.
Provided by the publisher for review, the books arrived unexpectedly in my mailbox just before Rosemary arrived on my doorstep. A fortunate coincidence. Like Rosemary, the author is no stranger to the practice of permaculture design. That shows in the 179, well-illustrated (drawings and black and white photographs) pages of his large-format softcover. The book isn’t just for the permaculture demimonde: it is relevant to virtually all Australian cities and towns below the Tropic of Capricorn, including the better watered but recently drought-affected big cities. I am taking about Brad Lancaster’s Rainwater Harvesting for Drylands and Beyond.
Let’s diverge. Australian governments, the whole three layers of them, have recently been encouraging individuals, companies and even government itself to take water-conserving measures. We now get rebates for installing water tanks and even bigger rebates if we have those rainwater tanks plumbed into our toilet flushing and domestic system.
When LP Hartley said, “The past is a foreign country; they do things differently there”, he might have been talking of the Australia of just 35 years ago. The ban on urban rainwater tanks as recently as that was in another time, another mindset. A time and place before the drought.
Now, local government sustainability education programs feature water conservation… how to harvest, store and use the stuff carefully. The Living Smart Action Guide, a 300 or so page manual I am writing for a local government sustainable living course, has an entire chapter on how urban people can make best use of water. The topic is taught in the course at Randwick Sustainability Hub, a Randwick Council enterprise instigated by permaculture educator, Fiona Campbell. It is led by a water engineer knowledgeable in all aspects of water harvesting and use, including grey and blackwater. Its presence in a course indicates the seriousness of the local government interest in water conservation in our sometimes parched metropolis. It suggests why Brad’s book is a publication for the times.
I find Brad’s book a literal mine of how-to information. Yes, I know he’s a North American and the Imperial system of measurement he uses survives only in Liberia, Myanmar and the USA, however Brad has been thoughtful enough to supply figures in both Imperial and Metric. The plants he mentions might not be relevant here, but I’m sure readers are smart enough to devise their own species list.
So, what’s in this book for we denizens of the southern hemisphere?
The principles of rainwater harvesting
First, there’s the eight principles of rainwater harvesting. In them we find parallels with permaculture’s principles of design.
Reading them, I’m reminded of the Action Research process I use in projects. It is based on the idea of look > think > act:
- Look—observe and measure to understand what is happening—in project management-speak this would be called baseline data collection.
- Think—analyse what you observe; learn about it.
- Act—to design and implement the project based on your observation, measurement and learning.
Let’s run through Brad’s principles…
PRINCIPLE 1: Observe and contemplate
This first principle might sound familiar to practitioners of permaculture design because it’s about starting with protracted and thoughtful observation, a principle coming from the early days of the permaculture design system and attributed to Bill Mollison, the co-founder of the system.
The principle is about taking the time to understand what goes on on our site, knowledge gained through the dual process of observing what happens and asking why it is so… why do those plants grow here? why is the soil here moister than over there? why does rainfall runoff flow this way? why is this area eroding? why do plants do well in this area but not elsewhere?
Observation reveals sometimes hidden processes and features in the landscape whether that is of rural farm or urban garden.
PRINCIPLE 2: Interact with water flow at the high point
Brad’s second principle is to think about water flow and how we might interact with it at the highest elevation of our land. He talks about moving water from retention basin to basin in a stepped progression down our site, assuming we have the slope to do that.
The top of the slope is where we begin our interaction with overland flow, the movement of rainfall across the surface of our land, and channel it into detention structures such as bunds (raised ridges), detention ponds and infiltration trenches or contour ditches, known in permaculture-speak as ‘swales’.
PRINCIPLE 3: Start small and simple
Brad’s third principle is to start small and simple, a suggestion that resonates with David Holmgren’s permaculture principle about small and slow solutions.
Although there are situations when we need big and rapid interventions, the principle is borne out in the food security and farmer education program I have a long association with in the Solomons Islands. There, in the Kastom Garden Program, the principle took the form of:
- Start small.
- Finish and consolidate the first small area.
- Start the next small module from the edge of the first.
- Finish and consolidate that area
- Repeat until the whole area is developed.
The approach is suitable for constructing the earthworks that will harvest rainwater on our site. It allows monitoring of work done by observing what is not working and fixing it. It shows what works well so we can multiply it. Field tested, the approach offers manageability and, as Brad suggests for water projects, reduces maintenance over time.
PRINCIPLE 4: Infiltrate water into our soil
The fourth principle is about infiltrating water into our soils, which is accomplished by slowing and detaining overland flow so that it has time to sink into the soil where the roots of our plants can get at it.
Brad talks about constructing contour bunds, earthern mounds raised across the slope on the contour of the land and which act as paths providing access through the garden.
PRINCIPLE 5: Manage excess water coming onto our site
Principle 4 leads nicely to Principle 5, that of planning an overflow route for the excess water that falls during prolonged rainy periods or storms.
Water moving under the influence of gravity has energy. Energy has to expend itself in doing some kind of work. Erosion is what it does when we do not plan what to do with excess moving water crossing our land during periods of heavy rain.
The planning includes making spillways to take water to a larger infiltration zone or, more likely in the city, to storm water drainage. We are responsible for the downstream impacts on other properties of our earthworks and water harvesting installations, so we don’t want excessive flows entering them. In the city, inattention to this could lead to a visit from your local council officer. There is a view that water unused on a property is wasted. It isn’t. It remains in the water cycle.
Overflow channels or spillways built to direct excess water flow should be reinforced against erosion by planting them with a mat-rooted species, perhaps a variety of durable clumping grass, or by paving them with closely-packed stones known as rip-rap. Earthwork water sinks can be planted to species which use larger volumes of water in their growth, such as bananas. In warmer climates, the root crop taro is sometimes planted because it prefers bogy soils. Native plants like sedges are also suitable.
PRINCIPLE 6: Maximise groundcover
Brad’s sixth principle is about maximising planted groundcover because it slows and infiltrates runoff.
Plant roots also pump soil water towards the soil surface, and the leaf fall becomes a mulch that breaks down to add the organic matter that keeps our soils open and porous.
PRINCIPLE 7: Design for multifunction
His seventh principle will be familiar to permaculture designers because it’s about stacking functions. It links with the principle of designing for multifunction which appeared way back in Bill Mollison and David Holmgren’s Permaculture One (1978, Tagari Publications, Tasmania).
Brad discusses strategies to increase productivity and make best use of limited space, and one of them I see as I look out the window. It’s a trellis that makes use of the side of the rainwater tank and, currently, supports a scrambling and largely unproductive pumpkin vine.
PRINCIPLE 8: Monitor our waterworks
The eighth principle is an important one, that of monitoring our waterworks and continually assessing their performance.
Doing this discloses where improvements can be made and is a way of learning more about our landscape. It applies the philosophy of the continuous improvement in design to our water systems.
The possibilities of technique
The first swale I saw in action was when I was a Landcare educator at Liverpool Council’s Calmsley Hill City Farm in south-western Sydney. It was carved into the sticky clay soil of the urban permaculture demonstration garden. Separating the large vegetable garden from the fruit and nut orchard planted immediately below its berm (the raised, downslope edge of the swale formed by soil excavated to make the trench), it did well what it was designed to do by permaculture designer, Bronwyn Rice—hold water where it could infiltrate the soil.
As water infiltrates, swales and berms form an area of moist soil immediately below. This slowly moves downslope under the influence of gravity and is accessed by the roots of fruit and nut trees and other vegetation.
The next swale I came across was at Habitat and Harmony Community Garden in the lower Hunter. This double set of swales, too, worked well and were full of water when I first saw them. Another swale I saw, trenched into porous sandy soil, detained little overland flow at all. That was because there was little, if any, even during heavy rain. Rainfall infiltrated the soil where it fell.
Swales are something that long ago caught the imagination of perma-folk and now we find them from farm to suburban backyard, however they are only one of many water harvesting earthworks and might not be the best response to water harvesting on all sites and soils.
We’ve already mentioned berms, which, unlike swales that are incised into the soil, stand mounded along the contour above it. There are mini-catchments, too, such as the ‘boomerang’ bunds Brad talks about —smaller, low-raised berms curved so they point downslope. He also mentions basins, another excavation and one made around trees in dry climates.
The banana circles popular with permaculture folk are an example of the basin model of water retention pit. The circles consist of a pit dug half a metre to a metre in depth at the centre. This retains runoff which can be moved into it via drainage channels. The excavated soil is mounded to form a raised lip around the circle and is planted to banana, which helps absorb the detained water, to pawpaw and other species including sweet potato which acts as an edible soil stabiliser. Vegetative waste is tossed into the pit where it breaks down into organic matter.
Also mentioned in Brad’s book are terraces, which are a means of turning a steep hillside into a series of flat strips for cropping. I was introduced to them by Badri Dahal, now living in Sydney but then with the Institute for Sustainable Agriculture Nepal, when he gave me a copy of the book, Sloping Agriculture Land Technology.
I was impressed when, in the early 1990s, I encountered a low hillside of terraces at the Angel Street Community Garden in inner urban Sydney. Brad suggests making low lips along the edge of the terraces to boost their water harvesting capacity.
Swales don’t drain
Despite their popularity, there remains confusion about swales in permaculture circles. It is due to the misunderstanding of this fact: swales hold water, they do not drain it away. Drainage ditches or channels move water from one place to another, such as to a dam. Drainage lines are excavated with a gentle grade, swales are made along the contour at the same height across the land.
Where they are large enough and where the soil is deep enough, swales can have pits dug into them at intervals. The pits act as cisterns to hold water, increasing the swales water retention capacity, and allow it to infiltrate the soil. Brad mentions this in his book.
So much more
There’s an informative and illustrated chapter on site analysis for the home and garden in Rainwater Harvesting for Drylands and Beyond.
As many reading this will know, site analysis and its accompanying needs analysis of how those who will live on-site want to make use of it, is the staring point of design. Brad provides formula for calculating harvest capacity, boxes of useful information and pages with scaled grids for doing your own design.
Brad Lancaster’s is the first of his three books on water. Rainwater Harvesting for Drylands and Beyond, Volume 1, leads to Volume 2, which is all about earthworks. Volume 3 covers roof catchments and cisterns — water tanks.
Timely volumes
Ours, we know only too well, is a dry country likely to become drier as climate change makes itself increasingly felt, especially in the south east. That is why, even in the cities clinging to our coasts, Brad’s manuals are so useful. What they do is take the ‘enrich soil + mulch’ message of permaculture educators a step further to shaping the ground to get the most from the rainwater that falls on and runs over it.
Now, a note of caution. Get advice in land shaping if you do not understand what Brad writes about or understand the hydraulics of your site. Consider your downstream neighbours and what happens to water leaving your land and entering theirs’. This is what Rosemary Morrow did before she reshaped her land to harvest water. If she — one of this country’s most experienced permaculture educators and designers — does this, then it’s only common sense that we do too.
So, should you invest your scarce dollars in this book and, perhaps, in Brad’s other volumes? I suggest the answer is ‘yes’. You will just have to apply a little observation and reasoning to adapt them to Australian conditions. Again, if you don’t feel confident doing what he describes, get help from a competent and experienced permaculture or landscape designer.
These are manuals for our parched times and gardens. They are easy to read, easy to understand and it is evident that they are written from the knowledge that comes of experience.
Lancaster B; 2006/2008; Rainwater Harvesting for Drylands and Beyond, Volumes 1; Rainsource Press, Tuscon USA; ISBN 978 0 9772464 0 3.
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