APPLYING THE WATER

Ashburton Guardian, Volume 68, Issue 134, 18 March 1948, Page 4

APPLYING THE WATER

Irrigation in Australia

SECOND OF,SPECIAL ARTICLES

“It will be realised that the question of water conservation in Australia is One of vital importance,’’ says Miss Marjorie Braae, winner Of the Robert Bel! travelling scholarship, in the second of a special series Of articles on irrigation in Australia.

■■ao quote U'om a document prepared uy uie a- list AYLiidura Alligation Trust ‘with growing demands tor water for irrigation purposes, . thequestion of provision oi aumonal storage calls tor urgent investigation . . . Tiie Commissioners oi tiie Trust fully support the efforts of other responsiDle authorities in pressing tor additional storage wherever possible and strongly urge that this important matter be given careful consideration.’

“Schemes for increasing storages are being put into operation or are projected for future construction. In the case of the Hume Reservoir on the Murray River, the present storage capacity is 1/250,000 acre feet, and provision has been made in the construction for the capacity to be increased to 2,000.000 acre feet (one acre foot being the volume of water neeesary to cover one acre of land to the depth of. one foot). When more water is available for irrigation, more land can be developed for settlement, although, at the present time, there is sufficient water to justify the preparation, in varying stages of progress, of- several areas for soldier settlement.

Soif Survey

“lii any new area the necessary first step in the preparation is a soil survey. From the resultant classification of soil types it can be decided what crops to grow and what type of irrigation will be the most suitable. This knowledge will shape the future course of ttie preparation work and will eliminate many of the mistakes that, in the past, were made through lack of experience. “The manner in which the water is applied to the land can be: (1) By means of the ‘spray’ system by which water is pumped into pipes and sprayed on the ground. This is most suitable for light soils in which citrus crops flourish, and crops such as vegetables-, which can be grown on a small arect.

“(2) By the ‘border’ system which is the one employed for irrigating pastures.

“(3) By the furrow system, which, as the name implies, is carried out through the medium of furrows, running from the head ditch through the area to be irrigated. Fruit trees are irrigated in this manner; in some cases three or four furrows are run between each row of trees, but, in other cases, one furrow running from one tree to the next, is all that is required. Tomatoes and all types of vegetables also are often irrigated in this manner.

“To prepare the land for irrigation by the border and the furrow systems requires a great deal of work, the first requirement being careful grading. As the water must flow by gravitation, it will be seen that a uniform slope must be attained, with no hollows or bumps, in order to ensure the successful working of these methods. In some cases it is necessary to pass the grader six or seven times over the area before the desired result is achieved, going up and down, across and diagonally. For the important foundation laying it is neeesary to employ surveyors and other experts. Supply channels and drainage channels must be in the right places, and, for pastures, the land must be divided into “bays” about half a chain wide and 5 to 10 chains long, eacli bay surrounded by a “check bank” about G inches high. The contours having already been mapped on paper, the check banks can be erected at right angles to the contours so that each bay will receive the requisite amount of water.

Stock and Domestic Supply

“It Is generally agreed that the first function of water in a thirsty land is to supply the needs of man and beast. This minimum amount is called a ‘stock, and domestic’ supply, and, in many parts of Australia, ibis is all that is available. The Mallee, * in North-west Victoria, is one district which receives such a supply. Once a year water is run through a channel 300 miles long so that the farmers in .this dry area can fill their storage dams and keep themselves and their stock alive, and grow, perhaps, vegetables and fruit. Then, water for irrigation is made available to provide a livelihood for an increasing number of people, within areas of close settlement and intensive cultivation.

“To illustrate the value of the increase in production after the introduction of irrigation, the following figures are given. For every foot of water applied in fat lamb raising, the land yields an additional £5 per acre, in dairying £lO per acre, and in dried fruit industry £2O per acre, in canned fruits £4O per acre, in market gardening £IOO per acre. “In every irrigation district, the land has a right to a certain amount of water, and this is known as the ‘water .right.’ The water right is determined by Ihe available supply, and varies in different districts. Where water is plentiful ihe right is a ‘2J in one,’ meaning that for every acre of land a farmer possesses, he is entitled to receive 2.' feet of water, per annum. Sometimes lie does, not require this amount, but his annual charge is based on its supply, and, whether or not he uses it, his levy remains the same. If, in any season he requires more than the amount to which he is entitled, he may, with the permission of the controlling authority, and if supplies are available, purchase an additional supply.

Strict Roster Observed

“During the irrigation season a strict roster is observed, so that each land holder receives his water in turn, and the amount he receives is controlled and recorded by a meter wheel which is placed at the point where his outlet leaves the supply channel. It must he noted here that, although this procedure is the most common, it is not adhered to throughout Australia.- as in some districts water is supplied only when it is requested by the farmer, and in some districts the supply is not recorded with the accuracy of meter wheels. “A sight causing immense satis-

faction is. that of a main channel, of the proportions of a swiftly, flowing river, cleaving the countryside and sending out branch channels in an intricate spreading network until the water gushes through the slowly turning metal wheels and thence into the slight, mild furrows and seeps into the ground in Nature’s first step towards prolific fulfilment.”