IRRIGATION IN CANTERBURY

Press, Volume LXX, Issue 21084, 8 February 1934, Page 9

IRRIGATION IN CANTERBURY

ADVANTAGES DESCRIBED ADDRESS BY MR T. G. BECK At the close of the meeting of the executive of the Canterbury Progress League last night an address on irrigation was given by Mr T. G. Beck, assistant engineer, Public Works Department. who has had- experience of irrigation schemes in the United States of America. At. present MiBeck is engaged in investigating the conditions in Ashburton county in respect of the possibilities of irrigation, and a portion of his remarks was devoted to detailing the advantages of irrigation. At the conclusion of Mr Beck's address, a member of the party of New South Wales farmers at present in Christchurch, Mr A. G. Kubank. gave some interesting details of the Murrumbidgee scheme. American Experience. Mr Beck spoke of the great irrigation schemes of the United States, and said that in the western states the demand for water for irrigation was so great that dams were being erected to catch the flow from the highest floods. American experience showed that bigger returns were obtained from irrigated areas where the rainfall was from 20 inches to 45 inches, than from actually arid land. The total rainfall on an area was not a reliable index to its suitability for irrigation; the rest was the rainfall during the growing season. Temperature was an important factor: very high temperature's were a disadvantage owing to the loss of water by evaporation. The topography of an area determined the irrigation method most suitable for it. Referring to the appreciation in land values in America as the result of irrigation, he said that approximately it was 75 per cent., as compared with ■ dry farm lands, in localities where the rainfall was about the same as in Canterbury, say 25 inches, and where similar climatic conditions obtained. Work in Ashburton County. He outlined the work being done in Ashburton county and said that a [ sort of topographical survey was j being made, from which it would be I possible to see what areas could be j irrigated from any particular point on j the main rivers. It would enable the | country to be divided into blocks which could be irrigated. Sources of water supply also were being investigated, and gauges were being installed to assist in estimating the amount of water that reaches the rivers. Enquiries were being directed to ascertain, where possible, the depth of ground water, the reason for this work being to determine areas that might be affected by adverse drainage conditions, and also areas that might be irrigated by pumping. In Southern California water for irrigation purposes was being pumped up from a depth of 470 feet. The question of suitable intakes also was being gone into. The Department of Agriculture was classifying the lands and the Department of Scientific and Industrial Research was making a soil survey. When these investigations were completed and correlated it would be possible to indicate the most economic irrigatable areas.

Suitability of Canterbury.

The first and paramount advantage passessed by Canterbury, Mr Beck saidi was the slope of the land and the uniform topography. Over areas of 100,000 acres the fall was surprisingly uniform. In Ashburton county the land sloped from 100 feet a mile at the foothills to 22 feet a mile near the sea coast, and the free or wild flooding method of irrigation was suitable for such conditions. The long periods in Canterbury when the temperature was above the critical temperature of 02 degrees Fahrenheit was an important advantage. The northwest winds, he thought, might be turned to advantage, providing high temperature and, rapid growth, moisture being supplied by irrigation. Another advantage was the wonderfully porous subsoil obtaining in almost every part of Canterbury, and certainly in Ashburton county. The natural conditions in Canterbury were favourable for drainage of excess water to great depth. The summer maximum of river flow, due to the melting of the snows on the alps, was another advantage. In Canterbury the amount of water available from rivers was so great that there was no chance of a shortage, and therefore water conservation was not of great importance. The main advantages accruing from irrigation in country already settled were increased production and the higher efficiency and regularity of production. In these times increased production was not wanted, but increased efficiency and regularity of production were important.

Mr Beck showed on a screen a number of interesting photographs of irrigation schemes in the United States, including some in which the generation of power was combined with irrigation. In introducing Mr Beck, Mr G. H. Holford, chairman of the league's irrigation committee, showed cinema pictures of the irrigation work being done at Seafield, Ashburton county, and in the Oxford district. Mr W. Stewart, Commissioner of Crown Lands, in rnovi«g a vote of thanks to the speakers, said that the experiences of the United States and of Australia in irrigation matters, as detailed by the speakers, gave them prospects of great success here. The motion was carried by acclamation.