Water-Table Levels Low In South

Press, Volume CVI, Issue 31077, 4 June 1966, Page 14

Water-Table Levels Low In South

Water-table levels on the Canterbury plains are normal for this time of year, except for South Canterbury, south of Timaru, according to the New Zealand Geological Survey’s three-monthly survey.

The survey excludes the area between the Rakaia and Rangitata rivers, for which measurements are not yet available. | In North Canterbury, as a result of the recent heavy rain, ground water levels in shallow wells have been affected almost immediately, and have risen, says the report. Deeper wells should show a rise in level in the next few weeks with the result that the annual lowest level or trough in water table levels will occur during May and June for North Canterbury. In South Canterbury, rainfall as yet has been insufficient to allow the ground water levels to rise to the usual levels for this time of the year. Levels in this part of Canterbury have not yet fully recovered from the low levels experienced during the drought of 1964 and 1965.

Rain has tended to be below average in South Canterbury for most months with the result that water-table levels are still low. Frequent rain during the winter and spring would result in a recovery of ground water levels. Rainfall in the winter when

less water is lost by evaporation is responsible for the recharge of ground-water reservoirs after their depletion in the summer. Thus, it is normal for water-table levels to rise during the winter, providing adequate rainfalls. “Now is the best time of the year to check pumps, pipelines and other water supply equipment to ensure that this equipment is functioning satisfactorily. Many times a well is thought to have gone dry when the trouble is due to a faulty pump or other equipment associated with the water reticulation.”