The Desert Rainforest
If the design for the environment which has been submitted isthe right way for the landscape then it must be the right way for all the specialpurpose landscapes of man, including the lands which are seriously drought proneand which have been the most difficult for man to hold with any great degree of permanence.
We have been encouraged to believe that droughts are gettingworse in Australia because the climate is providing less rainfall and the numberof consecutive years of far below average rainfall, is increasing. The opposite isthe truth. If indeed there was less rain the cause would be the devastation of landand not the other way round. And this change of climate caused by the deteriorationof the balance of the landscape over large areas, has occurred many times on thecontinents of the world during the last 3,000 years. Natural landscape of trees andgrass have been turned into desert and given a desert climate by the action and theinnocence of man of the way to work with the soil.
A particular grazing property had suffered six years of droughtwhen I arrived in 1966. The average annual rainfall was reputed to be 14 inches butless than half this average had fallen in the six years. The homestead sat on a clay-pana square mile or so in area. (Claypan aptly describes land from which the soil hasbeen blown away and nothing now grows on it.) The size of the property was nearly100 square miles. Of 6,000 sheep which the grazier had managed to hold through thedrought, 5,000 had died recently.
The property was afflicted by the terrible twins of despair--droughtand lack of finance.
We followed the usual routine; firstly, with the owner an inspectionwas made of the entire property within the 40 miles of boundary fence: secondly,we pin-pointed the principal features of the landscape and envisaged the design forall the land, and thirdly, we selected the most advantageous place for a starting-offproject within this design. The last item was critical since the improvement of theproperty had to be of unusually high significance and it had to cost so very little.
Like most properties that cover many tens of square miles inthese dry regions, this one had 'hard' areas which shed almost every drop of rain.The run-off from storms normally disappears in a bed of sand or a dry creek.
The plan was to intercept the rain run-off from some of thehard country with a diversion channel and lead the water to a large shallow storagedam for which we selected a site.
Apart from the land shape, we designed for the climate. Firstly,it was known that the drought could continue for years; secondly, there would besome rain every year. It could be as low as three inches but no previous droughtyear had been without rain. Therefore the design provided that the drought wouldbe broken before the drought broke and with as little as three inches of rain.
So far a day and a half had been spent on the examination duringwhich time the grazier had made his decision on the project. Another day and a halfcompleted the more critical levelling and pegging. I returned a few weeks later forone day to supervise the start of the construction which was completed by the ownerand his very helpful neighbours shortly afterwards.
What had been completed was a Keyline flood-flo irrigation project.It was made up of a diversion channel well over a mile long; a dam eight feet deepof only 6,000 cubic yards of earth moving which would cover with water somewhat lessthan 100 acres of land. The dam was equipped with a 25 inch outlet pipe. From theoutlet a long irrigation channel was constructed on a contour and from this channel,steering banks extended down the maximum fall of the very gently sloping land.
Except for the addition of the diversion channel the projectwas as described in the last chapter for the layout of a City Forest for the cityof Sydney. The principles are the same, the view would be vastly different.
During the year following construction, less than three anda half inches of rain fell. However, within a few weeks the first fall of 60 pointsnearly filled the dam and irrigation commenced a week later. Twice again in thisfirst year of exceptionally low rainfall--low even for a period of long drought--thedam received water from the 'hard' area to fill and overflow. Each time the dam filled,the water was used to irrigate, when the soil required it, until none was left. Theresponse of the soil and the fodder growth was nearly immediate and from the picturesreceived by the author this section of the property was quickly transformed. (Seecolour plates 6, 7 and 8)
The drought continued for five more years to break in Aprilthis year (1971).
The project and the property flourished through the drought.A second and much grander stage of the landscape design is now in train. The rainwhich broke the drought also filled for the first time a storage dam several timeslarger which had just been completed.
The above description contains the brief facts of a particularproperty; photographs are included in this book. What follows is not fact! Supposethat on this same property the condition had been even worse, climatically: Alsothat there were no good neighbours to help and no money to hire equipment to help.The grazier owns only a chisel plow and a 'ditcher', of both items there are tensof thousands on farms and grazing areas in Australia. (A ditcher is a grader typeblade attached to the three point linkage system on the rear of the usual farm tractor.Not very effective for digging undisturbed earth, it moves earth which has been previouslybeen ripped-up with a chisel plow.
What has landscape design to offer in these conditions whichwill cost less than the extremely economical project just described?
The basis of the design is the same as before but in this casethere is a change of emphasis. Instead of holding the run-off rainfall from the 'hard'or shedding area in a storage dam now the design is based on doing the best withthe little rainfall as it falls where it falls and particularly "during itsrun-off period"--but without a storage dam.
We have named this particular aspect of Keyline, "FocalisingRain Water." In essence it is a land preparation technique the same as for flood-floirrigation. The water from the hard area is controlled and focussed onto a selectedarea one tenth the size of the shedding area.
For instance, an examination of the property may disclose 5,000acres of hard country: a line is then located for a diversion channel which willcollect the rain run-off and lead it to a selected area of only 500 acres. The diversionchannel may have a slight fall to the start of the focus area where it becomes acontour and continues along and above it to serve as a water distributor--an irrigationchannel.
From the channel small water-steering banks extend for halfa mile directly down the gentle fall of the land dividing the focus area into waterfields of ten to 20 acres each. Openings are made in the irrigation channel intoeach field with the 'sills' of the water opening exactly the same heights. They remainopen so that instant and automatic irrigation results from every shower of rain whichproduces run-off from the shedding area.
A half inch of rain run-off would therefore provide the waterequivalent of five inches of rain on the focus area. Thus in a drought year the rainfallequivalent may be 30 inches and in an average year, up to 100 inches.
The best use of the focus area for the prevention of droughtlosses and for profit will depend on the circumstances pertaining on each property.Under the worst climatic condition, growing edible trees and shrubs for stock foddermay be the objective. Even so, for the reasons discussed in Chapters 10 and 11, legumesand grasses would be grown for a year before planting the trees for fodder. Moreoverpasture plants will more quickly provide the stock feed which may be so desperatelyneeded in a drought.
A focus area of 500 acres could carry 300,000 or more treesespecially selected for the purpose, all planted in rows to suit the manner decidedfor harvesting the fodder. The trees would continue to increase their capacity togrow more fodder and to grow it in the years when it may not be needed and storethe leafy fodder in top condition "above the ground" ready for when itis needed. They would also grow again in a drought after their fodder had been harvested.
The selection of trees would not be confined to the few nutritioustypes which now grow in these dry lands but could include any desirable species whichwere suited to the climate and to the plentiful supply of water. Such trees as thecotton-wood poplar and the mulberry, which now appear rarely and only separatelyin their ones and two's in moist places in these surrounds, may shortly be seen intheir ones and two hundreds of thousands.
It may sound incredible that severe drought losses could bewiped out and species of trees could grow which never grew there before. But thefact which is more incredible is that great damage has been suffered by Australia'slandscapes when there has always been such potential for tremendous landscape enhancement.
However, one point was the matter of cost. All the constructionfor the project could be done by a lone grazier with the chisel plow to loosen theearth and the ditcher to sidecast it into position. The first outlay would be forfuel and oil. Progressively the water fields would be fenced for stock control.
Focalising rain water would be fully effective whether the schemewas only one fifth the size on this proposal or five times larger. And such a lowcosting start would quickly lead to a near drought proof property after less thanan inch of rain.
This summary is the outline of a way to get a landscape designstarted off in severe drought and under conditions of financial hardship. The secondstage could be the construction of a dam as little as six feet higher to collectand store water for even more effective use on the focus area, which then would becomefully controlled irrigation land.
These techniques have wide application on the drought pronelands as well as in the more bountiful regions. They do not have universal applicationyet because not all properties have reliable run-off areas. Water shedding areascan be created artificially; some are even roofed over with corrugated galvanisediron to provide drinking water. There are much cheaper methods for creating thesespecial areas and no doubt new techniques will further reduce costs. But becausea focus area of less than one per cent of a property may double its production andvalue, a great deal of money could be economically spent on artificial shedding areas.
However on the thousands of properties which are now deterioratingand where these techniques of landscape design apply immediately, the focalisingof rainfall will multiply the rainfall equivalent on the focus areas by five or moretimes year in and year out.
RAIN FORESTS IN THE LAND OF DROUGHT on focus areas, are thestrip forests of this dry landscape. They are as logical as City Forests and as practicalas strip forests anywhere else.