June 14, 2006

MEDIA STATEMENT

Groundwater levels expected to benefit from snow

Groundwater levels in the Canterbury region is expected to benefit from this weeks snow over larges parts of the area. Environment Canterbury Hydrogeologist, Philippa Aitchison-Earl says snow is an excellent recharge mechanism for groundwater, as it melts and infiltrates slowly so that more reaches the groundwater than in a rainfall event. Groundwater levels are being measured this week in hundreds of shallow and deep wells around the region.

She says it is expected that shallow wells will respond quickly, but deeper wells will take more time. This occurred in 1992 where some deep wells recorded rises in groundwater levels over the following 3-6 months. “Without knowing the relative magnitude of the two events, we cannot predict the likely rise in groundwater levels. The snow event, while helpful, is unlikely to fully recharge the system, especially with the current low levels after several years of dry, low recharge winters, “ says Philippa Aitchison-Earl. “For example, after the 1992 snowfall, a deep well at Greendale rose 5 m, compared to an overall variation of 30 m in the 50 years of record.”

ENDS

© Scoop Media