Weather And Water Symposium

Press, Volume CI, Issue 29900, 14 August 1962, Page 11

Weather And Water Symposium

“The changing face of Canterbury” was the title of a series of lectures in a symposium on weather and water which formed part of the science congress yesterday afternoon. The lectures were given by three speakers and illustrated by slides. Dr. J. F. de Lisle, of the Meteorological Office, WelIngiton, spoke on the weather patterns of Canterbury. He made particular reference to the effect of the Main Divide, associated with winds of varying strength, on the cloud formations in Canterbury. Miany of Dr. de Lisle’s coloured slides illustrating cloud formations had been taken by Mr S. H. Georgeson, a well known glider pilot. Dr. de Lisle later answered questions on the fluctuations in the incidence of northwesterly winds in Canterbury and the reasons for the summer easterlies in Christchurch being so cold. Water Resources The water resources of Canterbury and their utilisation, from the generation of electricity to the provision of water sport facilities, were covered in an illustrated lecture given by Mr S. Hamblett, a chief engineer for the Ministry of Works in Christchurch. Mr Hamblett emphasised the need for adequate control of the use of ground water. “The supply is not necessarily limitless in the plains and there is also the danger of a back-flow of salt water from the sea.” Restrictions governing the use of garden hoses in time of drought could be very unpopular, Mr Hamblett said. Hoses were a major factor in peak demand which could be up to five or more times greater than normal on a summer evening, so the restrictions were very necessary. In a summary of his subject Mr Hamblett said that the production of hydroelectricity was entering a new phase with the plans for the development of the Waitaki basin which, he said, was particularly suitable for the generation of power. Mr Hamblett said that there was sufficient water flowing on the Canterbury plains to make up the deficit in rainfall during the year. By maintaining present works there would be sufficient water to meet all foreseeable future demands many times over. Flood Control Soil conservation and river control were inseparable and many important lessons could be learned from their history, said Mr E. B. Dalmer, deputy chief engineer of the North Canterbury Catchment Board, in a paper on river control.

Mr Dalmer traced the history of major flooding in Canterbury, particularly the flood of February, 1868, which resulted in the city council petitioning the Provincial Council to take measures against a similar occurrence. Flood control paid for itself in better farming, land utilisation, security, road access, communications and prosperity, Mr Dalmer said. An artificial state of maturity in rivers could be achieved if the present rate of shingle removal could be trebled, he said. Mr Dalmer said that flood protection was more an administrative than a technical problem. The protection had to be paid for and it was a matter of striking a happy medium between being flooded off the land or being rated off. “We must pay our tolls to live with the rivers—or perish.” Strontium-90 Lecture Rainfall .on the West Coast had a higher content of strontium-90 than rain in Canterbury and the content in the soil on the West Coast was consequently higher than in Canterbury, said Mr L. P. Gregory, of the Dominion X-ray and Radium Laboratory, who gave a lecture on “Strontium-90 in the New Zealand environment” at Canterbury University. Mr Gregory said that strontium-90 in the stratosphere from atomic explosions returned to earth over many years. Strontium-90 was hardly measurable before 1945' and most was found in the Northern Hemisphere, where most of the nuclear testing had been conducted. Strontium-90 was found in milk in a higher degree in Greymouth than in Christchurch, although the content in milk for all New Zealand had increased over the last year, Mr Gregory said. ‘The dose of strontium-90 content in the body is small compared with the natural background radioactivity in the body,” he said.