DIFFICULT LAND

Ashburton Guardian, Volume 59, Issue 46, 3 December 1938, Page 9

DIFFICULT LAND

MANY ENGINEERING PROBLEMS. RUNNING RACES OVER HILLSIDES NOT MUCH CROPPING SEEN. There are twelve official schemes in operation in Central Otago, and eight large storage dams, each over .50 feet in height, are the main sources of the supply of water, while there are a number of smaller ddms. Nevertheless, the work of getting water to the irrigable land is fraught with great difficulty because of the rough nature of a large proportion of the country which surrounds the valleys and flats where irrigation is being qarried on. Races have had to be run round the faces of steep and rocky hills, the engineers in charge having the utmost difficulty in maintaining levels over the many miles the races have to be cut. Some of the land under irrigation is ljigh in the hills, land that at a first glance would not recommend itself as being at all suitable, but water wa9 wanted and water is being supplied, and the countryside is responding in a remarkable manner.

The area surveyed by the farmers’ party included the towns of Ranfurly, Wedderburn, Omakau, Alexandra, Clyde, Cromwell, St. Bathans, Cardrona, Arrowtown, and the Ida Valley, the Dunstan Basin and the Galloway Flats. Once the water is within reach of the flats and valleys not much difficulty is encountered in placing it on the farms, but elsewhere the contour of the land makes it very awkward for the owner to bring about an even distribution of the water, which, of course, tends to run off in a number of directions to the gullies, leaving the higher parts dry. By dint of much labour, the farmers are making full use of the water and getting it to all parts of their farms, though, as one man told the visitors, “you are a slave while the water is going on.”

Though irrigation has been in vogue in some parts of the district for many years, it is only in comparatively recent years that the real demand for water has set in and the demand necessitated the construction of several dams. These storage places are located among the hills, some of them difficult of access, and the chief of them, with the date of their completion and other dimensions, are:—•

These twelve schemes supply water to about 50,000 acres, and there are 500 irrigators, as the farmers making use of the water are known locally. This gives an average acreage of about 100 for each man, though it was pointed out that it is not by: any means the true average. Because of the rocky nature of the ground it was anticipated that the losses of water from seepage would be very heavy, but the fact is that the losses are well within the anticipated figures. In cases the bottoms of races had to be puddled before they would carry the water. Machinery could not be used on the steep faces along which the races

run, so that most of the cutting of the channels had to he done by hand, which added to the cost of the work.

Irrigation is carried out on practically all the pastures within easy reach of the races and the large fruit-growing farms also make good use of the water, hut there is comparatively little cropping, as the land that is considered good enough for this purpose is much more difficult to regulate. The average rainfall at Alexandra, taking that town as the centre of the area under discussion, is 13 inches, though in six months of last year only two inches fell. A very wet season has been known to give a ranfull of 17 inches. The district is subject to severe thunderstorms, when large quantities of rain fall in the spaco of a few minutes, while cloud-bursts, such as that which recently washed out some of the orchard country, are not rare.

Crest Storage Date. Length. Capacity. it. acre ft. Ewoburn 1897 620 1,940 Manorburn .. 1914 387 41,310 Poolburn ... 1931 535 21,000 Lower Manorburn 1934 378 190 Conroys 1935 200 •880 Falls Dam ... 1935 510 8,400 Butchers 1936 225 1,190 Fraser liner 1937 450 4,120