25 Aug 2010

Well survey to shed more light on groundwater systems

1:59 pm on 25 August 2010

Canterbury regional council staff are surveying hundreds of wells in the Rakaia-Ashburton as part of a two-year scientific investigation to gain greater understanding of ground water flows and their interaction with aquifers and river systems.

The investigation is aimed at helping the council manage the region's fresh water resources.

Environment Canterbury groundwater hydrologist Mike Thorley says the piezometric survey is a huge logistical exercise, requiring the water pressure to be measured in 350 wells in mid-Canterbury, on the same day.

Mr Thorley says the survey, to be carried out on Thursday, will find out which way groundwater is flowing, and give an understanding of how water is moving from the rivers through the ground and ultimately to the coast.

In Canterbury, only the central plains has been mapped in any detail, he says. That was done by the Catchment Boards in the 1980s.

Mr Thorley says there will be a follow-up survey at the end of the irrigation season in late April or May next year, to measure the change in seasonal groundwater levels.

As well, regional council and NIWA staff will be measuring flows in the Rakaia and Ashburton rivers.

He says the knowledge built up is essential when it comes to allocating water consents.