Irrigation Practice in Landscaping – An Alternative View



www.capewaterplant.co.za

Irrigation Practice in Landscaping - An Alternative View

For the past 30 years or so, very little has changed in this industry in terms of methods and results, and water has been an expendable commodity like there was no tomorrow in sight. One could say that this is roughly the time that landscape irrigation, as we know it, came into its own right. Considerable technological advances have been made with reliability, materials of construction, massive advances in electronics and so on. Designs have improved considerably and the components required have become (in some respects) cheaper, they are much more user friendly and it seemed like anyone could make these things work.

One thing that hasn't changed- a sprinkler is still a sprinkler. In fact, since the invention of the modern sprinkler say 70-80 years ago, nothing has changed much. Water still gets moved from the source, through the body to the nozzle. What happens to the water after it leaves the nozzle is the part that we are interested in. The water still travels a set distance from the nozzle to where it falls, be it plants, patios or other objects. The behaviour of that stream of water in the atmosphere is still the same.

When the Cape southeaster blows in summer that sprinkler still loses most of the water to the atmosphere- in fact sometimes close to 100%. Water has become hideously expensive- you don't just pay for the water, but also the hidden sewage surcharge levied on the actual amount of water used. In midsummer Cape Town, a very brisk southeaster, temperature in the upper 30's, no rain, most of the water from the sprinklers blowing in the general direction of Robben Island, it's panic stations. Irrigation contractors speed from one side of town to the other, repairing things, adding sprinklers, doubling run times…but to no avail- the newly planted seedlings from the nursery are taking terrible stress- will they survive?

Next thing the client phones the contractor. Has the City Council gone mad? He's never had a water bill like this in his life. Have they made a mistake perhaps? No, they haven't. How does one rectify the situation, is there any solution without destroying the garden? Enter drip irrigation for landscaping.

To some this is a swear word, many ignore it as it's an unknown quantity, others are mildly curious, some reject it outright because they've been told its rubbish- unworkable, unconventional, unwhatever. Yet to a handful of contractors, designers and landscape architects, it's become an incredible tool to achieve results of a standard never known before. At this point it has to be stated (for the non-believers) that there are near 400 of these projects that exist in the greater Cape Town area. These include some very recognisable places like the new International Convention Centre (inside and outside gardens), the V&A Waterfront Marina development (premium property, probably the most expensive residential real estate per square meter in Africa), and many others, some more recognisable than others, but no less impressive projects.

Drip as used in landscaping has its origins in agriculture. The superior quality of crops watered by drip cannot be disputed, and many of the same rules and techniques used apply for landscaping. The technology involved is very different in just about every respect, in comparison to traditional sprinklers. In fact drip is perhaps the most basic method of watering a plant, and some say the principles of drip irrigation can be traced back to the time of Babylon's hanging gardens.

Having said that drip has been used extensively in agriculture, one has to consider that different crops have very different needs. For instance a short-term cash crop will grow for say, 10-12 weeks. At harvest it may not be possible to salvage the drip lines and the pipe becomes waste at this time. The pipe is of an extremely light duty construction and cheap, it is designed for a 3-month lifespan. There are many intermediate grades of drip pipe depending on the required lifespan of it, and is not recommended at all for a permanent landscape. The only integral pressure compensated drip line in the world that is specifically designed for landscaping applications is Netafim's Techline.

The manufacturing process of this range of drip line is unique in every respect. No other irrigation company in the world possesses the technology, or has ever been able to replicate this exact pipe and one may suspect that this is a primary reason for an active disinformation campaign waged in different forms by the major sprinkler manufacturers and others over recent years. This disinformation campaign, by the way, is well documented. Which makes it fun to be in the drip irrigation business, never a dull moment.

Let's look at an example of how drip and sprinklers shape up against each other: Recently the agent of a very large commercial site (the largest entertainment complex in the Western Cape) in Cape Town requested us to do a cost and viability study on how to cut the water bills on one portion of this site. The monthly water bill on 2 water meters is R48000/ month combined. The total area described is some 60000 sqm and water is billed at bulk rates of about R3.20/ kiloliter. Our proposal was to put a grid at normal spacing over the entire described area, to deliver 20mm/ week. That's 20mm/ week in the root zones, with close to 0% losses to evaporation and other factors, which means that's the amount applied.

Initial tested calculations showed a projected consumption of about R15500/ month, give or take a few bob. The savings seemed quite impressive, until we made more sums. Annual consumption that the drips would save comes to + 122 million liters/ year! Consider this: that is equal to the monthly free water subsidy of 6 kl to 20000 households, which can be translated to sustaining upwards of 100000 people in poor areas. On the subject of saved costs, consider this site spends many thousands of rands replacing vandalised and stolen sprinklers annually as well.

When one looks at these figures, crazy as though they may seem, there are invariably questions that start coming up. Which designer can justify that kind of waste, and to add insult to injury, the planted areas described don't look that great either, meaning it would look better under drip. Moral and environmental issues become prominent and no one will take responsibility (well, that company did go bust beginning last year). How irrelevant is drip irrigation under these circumstances? Or under any circumstances? These circumstances repeat themselves many thousands of times over on a different scale in the majority of private gardens. Accumulatively the figures will be staggering- to counter this we'll have a bit of spin by the relevant people and everything is ok again. Or is it?

Another even more disturbing question begs to be asked: Is this kind of water wastage allowed in the country of origin of these sprinklers? No. Does that mean South Africa is regarded as an unsophisticated third world market? Is this country a dumping ground for (some) unwanted technology? Everyone knows that the use of these devices is totally unregulated here. This is merely a thought that comes to mind.

It is sad to see that through disinformation, fuelled mostly by ignorance and perhaps fear; some influential individuals in the industry are discouraging in the strongest possible way the average irrigation practitioner to discover a whole new discipline. A serious handicap though is the fact that no proper training course exists in this country that properly covers all aspects. Its not a secret that drip in landscaping is unforgiving; it runs to a very specific set of rules and things happen in a set sequence. It will let you down badly if this is ignored. But once this part is properly understood it becomes incredibly simple.

Hours of hydraulic and precipitation rate calculations required for very large scale sprinkler installations (sometimes fairly meaningless as the effect of climate in Cape Town cannot be calculated accurately) are not required for drip on the same scale- once you know the rules the same calculations can in fact be done in minutes, without a calculator if you like. The difference is that known constants are used over any area, and it becomes like grade 4 arithmetic after that- and no corrections have to be made for variations in climate. Because of its deep watering characteristics and simplicity of operation, sophisticated feature packed controllers or fancy computer programmes aren't required. The drips are quite happy to run on a simple dual program controller, and it doesn't need to be top of the range either.

Some time ago I did offer to structure a comprehensive practical and theoretical training course to the relevant irrigation industry organisation, but no one responded. A guaranteed response to any statement made regarding drips is a standard range of reasons and remarks why drips don't work. We been down that road too many times and the objections have become tired. Over time we have found methods to overcome what was legitimate objections and even invented new methods along the way. As I said, there are nearly 400 places to go see the results of these things. One has to say that this method of doing things favours the creative and enthusiastic individual, who is not bound by meaningless traditional rules and taboos, and who seeks a more logical way of solving old problems.

Tradition in modern society has great relevance, but more often than not tradition will also be the cause of stagnation, and even bankruptcy. We live in an ever-changing world with new demands (and one can almost say changing rules as well) all the time that demands innovation, inquisitiveness and at times unconventional thinking to stay abreast, never mind ahead. Norms set by peers may or may not be relevant. Conforming to norms one perceives as being absolute may corrupt the mind, for it doesn't demand creative and sober thinking. Compare it to a herd of sheep that doesn't know they are going to slaughter, if you like.

This irrigation industry does not exactly have an enviable track record, no matter how much some may try to regulate it. Some high profile projects are seriously flawed and look sad, and there seem to be a lack of responsibility, liability or good faith on the part of the people that did these jobs. Many will claim that what they are doing with traditional methods is water wise, without having an idea what the concept really means in practice. Perhaps it is because no one ever really defined properly the concept of water wise on paper or it hasn't been important enough. Or the concept may be manipulated or altered to rationalise their own perceptions perhaps. It is understandable that no one will willingly surrender their market share to a concept that more or less invalidates the traditional rules that have become the norm.

There is no such thing as a sprinkler that is truly water wise, and the laws of physics and common sense will prevent such a device from ever being invented. It is true that some sprinklers may be less efficient than others but at the end of the day they all waste unacceptable percentages of water when subjected to operational conditions, in comparison. Ironically, the water applied to them properly sustains very few landscaping projects.

Of the Western Cape landscape projects submitted for the annual (2003) SALI awards, 2 projects of the 4 gold awards were done in drip. This may be a sign of changing times, as proportionally there were only a small number of drip projects completed in the past year compared to others. What would the reaction be if water efficiency (or rather efficient use thereof) becomes the primary criteria on which projects will be judged? Irrigation contractors are known to be very critical of any projects not done by them. It would be interesting if they went to West Quay Office Park or the new Cape Town International Convention Centre for instance, and comment on what is so fundamentally wrong with the methods employed, or how this whole concept is unworkable. It would make for some interesting reading.

Landscape Irrigation Association of S.A (LIA)
The LIA established itself as a body to regulate the landscape irrigation industry, and has stated amongst its objectives "Encouraging high standards of water conservation, design, quality and workmanship through training and certification in accordance with the National Water Supply Regulations Act and SA Qualifications Authority". In Cape Town in particular this statement is misleading and untrue as there is little or no evidence of any realistic attempts or implementation of water conservation, for reasons explained earlier. Judging by the standards and results of conventional projects completed in recent years rather suggests that the opposite is true, and this has been happening all the time on a massive scale.

The LIA is primarily a marketing platform for importers and suppliers of various types of irrigation equipment, as well as contractors wishing to be associated therewith. It seems that on a secondary level there is little interest to pursue new concepts and ideas as these may clash with traditional values, markets and techniques. If the LIA wishes to remain a credible player in the industry they will have to accept that priorities have changed and that traditional brand loyalty doesn't count for much anymore. Instead of encouraging the proliferation of traditional systems that waste more than half the water applied, the association should rather take a more pragmatic approach to water conservation in this context, before legislation forces them to. The traditional sprinkler, as we know it may yet end up on the scrap heap of redundant technology, or with severe limitations on its use. This is not so far fetched an idea when one looks at these devices and see what they do. Few people realise it or are willing to admit it, but running costs have already priced sprinklers out of the market.

Consider the following: the Western Cape winter rainfall for June 2003 is the lowest figure recorded since 1978, and supply dam levels are becoming dangerously low. Unless sufficient rainfall is recorded very soon it is certain that water restrictions will be put in place. The problem is that greater Cape Town's population is probably 3 times that of what it was in 1978 and there weren't thousands of domestic and commercial sprinkler systems pumping many millions of litres of water into the atmosphere at that time. In any event it is certain that the cost of water will rise significantly, and what happens if the available water supply should ever fall to the point where agriculture fails and peoples lives are threatened? One sincerely hopes this never happens but it is certainly not impossible.

City of Cape Town Water Innovation Centre
Cape Town's population is currently rising at a rate of about 3% per year, which results in a proportional demand increase on available resources. This is a reason why this experimental facility was established, and to evaluate on an ongoing basis comparative testing with sprinkler and drip devices, amongst other things. At the same time we are busy documenting individual examples by means of compilation of visual and technical material, which will be used by the proposed media centre at this facility. If the situation warrants it, this may well form the motivation for amendments to current water consumer related legislation.

How does one define water conservation on paper, in the context of landscape irrigation? One can imagine that it may read something like this: "Containment of any preventable water losses for the duration of time that water is applied to planted areas, and using such irrigation devices which do not incur noticeable water losses either by evaporation or spillage onto unwanted areas." In other words, using a device that doesn't waste, installed by a qualified person that properly understands the dynamics thereof. And it will need to be implemented without ever exceeding an average of 20mm per week after establishment of new landscapes.

It is worthwhile to get hold of the September 2002 copy of the National Geographic magazine, containing an article on what is happening to the planet's water supplies. This is a sobering and disturbing view, with a number of excellent examples illustrating the state of fresh water worldwide. It states also that the biggest single cause of dwindling available fresh water supply is the universal use of outdated and inefficient irrigation practices and devices. We are attempting to obtain this article in electronic format from the publisher, subject to their agreement.

Maybe one day we'll nickname the Cape southeaster the wind of change……

Information supplied by Philip Botha of Cape Waterplant. For more information contact , or www.capewaterplant.co.za or telephone 021 551 1911.

Bookmark the permalink.