K.G. Murray Publishing Company

Transcription

The Australian Keyline Plan for rural land development has spread to many countries. This report of the operation of the plan in New Caledonia illustrates one aspect only of Keyline, namely, the Keyline Flood-Flow Irrigation System. Designed especially to achieve fast and low cost fully controlled irrigation on the flatter land, this system provides planning and water control techniques which greatly increase the area of land which one man can irrigate in one day. New Caledonia! Cattle country! With the same latitude and a similar climate to the Rockhampton area of Queensland. Rainfall is 33 inches per annum. This is the left bank of the swampy valley of the Salée River on the sixteen thousand acre Muéo cattle station. Mr. Tom Johnston, right, and Mr. Ken Johnston, of the Société d'Elevage de Muéo, are members of a family who settled in New Caledonia in the 1880's. This stream near the edge of the swamp would be used for irrigation as a part of the Keyline Plan for the station. But then came a crucial question! Could irrigation start soon enough to save the 100 or so head of cattle which may otherwise die in the dry months just ahead? This is the swampy valley of the Upper Salée River. The small stream flows in the swamp on this side of the valley. Keyline assessment of the whole property showed that this stream could be developed quickly into a very valuable farm water resource for irrigation. The upper Salée could be turned into a diversion channel thus, taken across a small creek and into an irrigation channel extending for a mile across the plain. All this land below an irrigation channel could then be irrigated. An earth dam was constructed across the small creek. The earth wall was made to serve also as a viaduct, and thus to form part of a continuous channel, three miles long. The river water then flowed via the diversion channel, across the wall channel, and into the irrigation channel. A control was placed on the river diversion channel at this point so that the river water could be used to keep the lake filled. Three weeks later the construction was completed and in a few more weeks it looked like this from a height of 2,000 feet. The new river diversion channel can be glimpsed on the left of the sheet of water. This newly constructed Keyline lake has a surface area of about ninety acres. It has the natural catchment of the small creek, but in addition, the flow of the Salée from the river diversion channel ensures that it can be kept full. The shore of the lake now shows the effect of the severe drought. But to go back to the beginning — if water is to be used, it must be first brought under complete control. A water-gate was installed to control the river flow to the diversion channel. The water-gate consists of an iron frame with fins which are embedded well into the earth around the channel and firmly fixed with concrete. There are two doors to the river water-gate, a sealing door and a leaking door. It is a simple matter to "turn-on" the river. First, the water is released from between the two steel gates to take the pressure off the sealing gate; it then opens easily. Second, the leaking gate is opened releasing the present full flow of the river into the diversion channel. The excavated earth from the channel was placed to form a levy bank designed to prevent river floods entering. To shut off the river, the leaking gate is closed first. Most of the flow stops. Now the sealing gate is lowered and placed in position. The leaking gate is then raised which causes the pressure of the water to seal the outer gate. Looking upstream toward the start of the river diversion channel — and now downstream. It crosses a rocky ridge called Blue Nose Point and a small rocky gully. We are looking upstream again with the Salée swamp in the background. The swamp is 500 yards wide. Over half a mile from the river water-gate the diversion channel changes its form as it commences to leave the river. The channel, now well away from the Salée swamp, traverses gently undulating country. Still looking upstream, a small bulldozer clears land for another part of the development. Mr. Tom Johnston follows the water towards the lake. Below the channel, all the undulating country is being cleared for Keyline Pattern Irrigation. A description of this development is not included in the film. The lake is only a couple of hundred yards away now. The water of the river arrives at the lake. The construction of the river diversion channel was completed in a week with a medium sized bulldozer. The small bulldozer helped with the clearing. The water flows on and into the lake and past the temporary galvanised iron water-gate, which, when opened, diverts the water across the elevated channel on the lake wall. This gate is now open and the water from the river flows down to the elevated channel on the wall of the lake. This earth wall across the creek has a thirty-five foot wide elevated channel and a roadway on its crest. The water from the river diversion channel can thus be diverted into the lake or across the wall to the plain for irrigation. We are looking along the irrigation channel towards the lake. The irrigation channel is formed by a two feet high bank which was constructed across the plain from the lake wall to the road a mile away. Falling at one in five thousand, the water flows on the upper side of the bank where the men are walking. It was constructed in a day. Smaller banks, 150 feet apart, run from the irrigation channel down the fall of the plain. They form the sides of the irrigation bays down which the water flows. Keyline Flood-Flow Irrigation could be likened to the orthodox border check system used in public irrigation districts. The essential differences are; the Flood-Flow land preparation costs are less than one tenth; the irrigation bays are upwards of twenty-five times larger; the rate of water flow to individual bays may be fifty times greater; water use efficiency is superior and man-power effectiveness is increased in proportion to the greater flow of water. Mr. Bill Wynn, on the right, has been appointed manager of the irrigation developments on Muéo. He talks with Mr. Tom Johnston. Flood-Flow Irrigation can utilize upwards of four times this quarter of a million gallons an hour dry season flow from the Salée swamp. So to increase the flow in the irrigation channel, water gates were installed on an old flood channel which now forms a long arm of the new lake. The water-gates release for flow the top 18 inches of the water of the lake, which then joins with the water from the river in the irrigation channel. The irrigation stream flow already available on Muéo Cattle Station is upwards of one million gallons or 4,500 tons of water per hour — a Flood-Flow all very easily controlled by one man! The irrigation procedure is as follows: The river water-gate is left open and the river channel flowing. This water is diverted across the elevated channel on the lake wall and into the irrigation channel. Here it is joined by the flow from the lake water-gates. Now the water-gates in the first irrigation bay are opened and the combined flow commences its work. When the irrigation stream reaches a predetermined position in the first bay, the water-gates on the next are opened and the first closed. In this manner twenty 10 acre bays can be irrigated in one day. For comparison, a farm irrigation rate of four acres per day would be considered above the average. This Keyline Flood-Flow Irrigation, where one man may do 200 acres in one day, is applicable to farming on the flatter land, whether it be for grain crops, or for pastures. for sheep and cattle — or for dairying. Although there is positive water movement in irrigating two hundred acres in one day, there is no soil disturbance or wash, despite the newness of the work. The reason for this is that each bay is made in width to suit the volume of the irrigation stream and the slopes of the land. This flow is a quarter of a mile down from the irrigation channel. Any run-off water from heavy rainfall and drainage, returns to the Salée River two miles below the river water-gate. As soon as the irrigation of this section of two hundred acres is completed, the river diversion channel is closed off from the irrigation area and then this water flows on into the new man-made lake. The lake, at eight feet deep, is relatively shallow, but the surface size is such that two hundred acres of irrigation lowers the lake only a few inches. It is fully replenished by the water from the river diversion channel in two days. In this irrigation channel the water is actually flowing to the left. These dry winds which blow each day from September to December appear to be reversing the flow of the water. The construction work at Muéo for this stage of the project was completed in three weeks. Two hundred acres of irrigation is considered a large area for any property, but this was only the start from this one farm water resource development. There is still water available. But for the next stage of the project, the water has to be lifted four feet higher on the plain. A site for a low-lift pump, which would lift the water for the new area, was selected on the long arm of the lake formed by the old flood channel. Before constructing the new irrigation channel and the new steering banks, the 24 inch pump was set up on the long arm of the lake five hundred yards from the earth wall. It was tried out as soon as it was in position. The water flows rapidly to the pump in a restricted section of the long arm of the lake. The test Flood-Flow of the pump is allowed to spread down over the plain to the first irrigation channel half a mile away. The flood channel arm of the lake extends six hundred yards from the earth wall. The second irrigation channel as constructed to the road boundary and irrigation from the pump commenced. The three-quarters of a million gallon per hour discharge from the pump now flows into the newly constructed irrigation channel and irrigation proceeds exactly as before. In the meantime the diverted river flow has raised the lake water level a further ten inches. The arm of the lake is on the left of the new irrigation channel. The average cost of the irrigation water at Muéo is less than a tenth the price paid by farmers in Government Irrigation districts. And not even the largest public irrigation scheme can deliver water to individual farms at a flow rate anything like as great as at Muéo. On the right is the new irrigation channel. The pump site is near the small clump of trees on the long arm of the lake. The Keyline work at Muéo started in May, 1963. The pump scenes were photographed in October of the same year. At that time, the surrounding country was in the grip of severe drought, aggravated by continuous dry winds. One month later stock losses were severe on other areas. On a property the size of Muéo carrying two thousand five hundred head of cattle, the losses during an extra dry season such as 1963, would have been over one hundred head. This immediate result of saving stock losses alone is of greater value than the cost of construction of the Flood-Flow irrigation. There are countless opportunities on farm and grazing properties for low cost water developments and irrigation. However, the many opportunities, such as those at Muéo in New Caledonia, may remain undiscovered and not even suspected. But Keyline principles will not only discover and plan such developments quickly, but whererer these principles are applied they will reverse the processes of soil deterioration and soil erosion. Regardless of the many methods of applying water to land there is a Keyline Plan for every individual area! This film shows only one aspect of the application of the Australian Keyline Plan to the development of Muéo Cattle Station in New Caledonia.