Environment Canterbury has begun a project in the Timaru district to better understand the interaction between surface water and groundwater.

Sam Nevin, a Timaru local who this year completed a Geology/Geography and Environmental Management degree at Otago University, will begin by mapping local streams and rivers for the purpose of identifying groundwater recharge areas. He will also be identifying any springs (effectively points of groundwater discharge).

Hydrogeologist Dr Lee Burbery says the initial fieldwork will cover the area from Mt Horrible to the coast and is part of the ongoing investigations work Environment Canterbury undertakes to better understand the nature of the freshwater resource.

"Much of the Timaru area is covered by surface deposits of a fine grained wind-blown sediment called loess, beneath which lies volcanic basalt. Loess is fairly impervious to water, so restricts the amount of surface water – be it rain or river water – that can penetrate down through it to become groundwater.

"Between Mount Horrible and the coast, the greatest potential for any surface water to recharge groundwater is where streams and rivers flow over sections where the loess is either thin or absent.

"We need more detail, which the surface mapping project will provide, so we can develop and refine our models of the interaction between surface and groundwater.

"The work will require access to streams and rivers on private land.  Land-owners will be contacted prior to Sam or any other Environment Canterbury staff visiting their properties," says Lee Burbery.

Sam Nevin says the work is a welcome opportunity to apply the skills in geological mapping and interpretation he has acquired at Otago University.

"The initial phase of stream mapping will keep me busy until Christmas," says Sam. 

"In January the second phase of the project will involve mapping springs in the Cannington Basin area, upstream of the Huts recorder."

Dr Burbery says the two phases of the project are linked and will provide a better understanding of the complex interaction between surface and groundwater in the Timaru district. 

"We are keen to have local knowledge about springs, which adds to our scientific investigations, so invite people to contact us if they have information they think may be of interest to us."

For more information: Dr Lee Burbery, Hydrogeologist, Environment Canterbury
(03) 363 9357.