THUNDERING WATERS Leaving Tunnel At 115,620

Dominion, Volume 37, Issue 2, 28 September 1943, Page 4

THUNDERING WATERS Leaving Tunnel At 115,620

Gallons A Second

Dominion Special Service.

AUCKLAND, September 27.

A remarkable thunder of waters has been-created by the 1000 ft. tunnel at the Karapiro hydro-electric works in consequence of the sharp rise in the level of the Waikato River following last week’s heavy rain.

The tunnel is 25ft. in diameter ami the normal volume of water which passes through it is 7000 cubic feet a second. The water a week ago was within two feet of the top of the tunnel. Since then the river has risen. 20ft. in the large pool formed in a bend, upstream from the tunnel inlet at Karapiro. The tunnel is completely submerged, the top being 18ft. below the river level. A huge vortex has formed in front ot the inlet, and the water eddies round at a terrific pace. • A few chains below the inlet is one of the coffer dams made of earth and rubble which was completed three weeks ago. Fear was entertained that the dam would be washed away, but there is no movement in the water fronting the dam, and the structure remains intact in spite of the heavy pressure against it. A wild spectacle of turbulent water was witnessed at the outlet of the tunnel yesterday, as water poured but at the rate of 18,500 cubic feet a second, or more than two and a half times more than the normal volume. The present rate equals 115,620 gallons a. second. The pressure with which the water is forced out of the tunnel creates a violent turmoil. It is swirled, round at a great speed and is thrown, many feet into the air. No rapids in the Waikato River compare with the cataract caused by the tunnel with the river at its present level. The partly-completed second coffer dam a few chains above the outlet is fully submerged, and probably much of it has been washed away.

The Taupo Lake has reached an abnormally high level, and, though it Is desired in the interests of Taupo and Tokaauu residents that the lake waters should be reduced as soon as possible, the flow is being regulated completely by the operation of the gates in order to minimize any risk of damage al the Karapiro works. The flash boards on the weir at Arapuni, which, when in position, raise the level of Arapuni Lake by 4ft, or 2J per cent, have been removed in order to reduce the lake level. The river is rushing over the spillway at a depth of sft.. and at a speed which presents an impressive scene. The river at Hamilton yesterday was Oft. above its normal level and the Hamilton wharf and several goods sheds were immersed.