Possible Power Source

Press, Volume CIX, Issue 32266, 8 April 1970, Page 10

Possible Power Source

The possibility of electric power generation being incorporated in an irrigation scheme for the land between the Selwyn and Waimakariri Rivers is envisaged by the Northern Central Plains Irrigation Committee which yesterday made submissions to the irrigation committee of the Water Allocation Council.

The committee said that the Waimakariri had been considered as the sole source of water for the northern central plains when tan irrigation scheme had been prepared by the Ministry of Works in 1956.

The draw-off had been estimated at 1500 cusecs, which was more than the lowest recorded flow of 1462 cusecs in May, 1960, and little less than the normal summer flows of 1600 to 2000 cusecs. At present it appeared that a 200 to 300 cusec draw off for this area was all that could be expected from the Waimakariri if the greater priority for alternative uses was recognised. The committee felt that water storage in the Waimakariri basin could provide a larger and more constant summer flow, but the economics of tihs would need detailed study. Rakaia As Source

The Rakaia, with a summer flow of 3000 cusecs, seemed to be the logical source of water for an irrigation scheme for the major part of the northern central plains. However, if water was brought across from the Rakaia to this area consideration would also have to be given to the possible

demands for irrigation water of the southern central plains area. Assuming it was feasible to irrigate the entire 200,000 acres in the northern central plains district, the committee said, a source of 2000 cusecs would have to be made available.

If an intake was situated in the Waimakariri Gorge proper above the 1200 ft contour water could be brought across the Kowai Bush flats, siphoned under the Kowai River and on to the Springfield flats at Keens Road. The top section, of about 30,000 acres down to just below the 800 ft contour, would require 300 cusecs of water from the Waimakariri. The balance would then come from the Waimakariri or Rakaia Rivers. If an intake was situated in the Waimakariri Gorge proper above the 1200 ft contour the committee said that the top end of the scheme, down to just below the 800 ft contour, of about 30,000 acres would require 300 cusecs of water from the Waimakariri. The balance would then come from the Waimakariri or Rakaia Rivers. Higlibank-Type Station The intake on the Rakaia, if situated at the Rakaia Gorge Bridge, would allow water to be brought up the terrace on to the Te Pirita flats at about the end of Sleemans Road. The main race would then cut across the top of the Te Pirita flats to Coalgate, and across the northern central plains just above Darfield, about the 800 ft contour. Surplus water could then be discharged into the Waimakariri at the end of Bleakhouse Road.

In such a scheme it would be possible to incorporate a hydro-electric station of the Highbank type at one of two sites—on the Rakaia at the end of Steeles Road or on the Waimakariri at the end of Bleakhouse Road. The committee said it felt that dams on the Rakaia or Waimakariri would allow for greater control of river flows and more economical use of the total water available for all purposes. The submissions were presented by the chairman of the committee (Mr A. D. Mulholland), supported by the secretary (Mr R. H. Williams) and Mr D. G. Watson. “This is one of the most realistic and factual set of submissions that we have seen,” said Mr A. C. Begg, a member of the irrigation committee. Mr Mulholland said the submissions were supported by the Hororata-Dunsandel branch of Federated Farmers.