The Canterbury Regional Council has started initial fieldwork to gain a better understanding of the interaction between ground and surface water in the Timaru district.
The first phase involves mapping streams and rivers between the coast and Mt Horrible near Omarama, to work out where groundwater may be re-charged, and identifying springs which discharge groundwater.
A council hydrologist, Lee Burbery, says a lot of the land in the Timaru district is volcanic basalt covered by deposits of a fine-grained wind-blown sediment.
He says the sediment is fairly impervious, so it restricts the quantity of surface water which can filter through it to become groundwater.
Dr Burbery says the greatest potential for any surface water to re-charge groundwater is where streams and rivers flow over areas of either no sediment or only a thin layer.