WELLINGTON, Nov. 28 (Xinhua) -- A study reveals some New Zealand wells contain groundwater up to 40,000 years old, raising concerns about sustainability.
New Zealand scientists unveiled a National Groundwater Age Map and tools for sustainable management of hidden groundwater resources, from national through to local scales, a media release of Earth Sciences New Zealand said Friday.
The six-year research program, based on over 1,000 samples, has combined environmental tracers and modelling, with traditional Maori knowledge, to reveal new insights about New Zealand's underground aquifers' age, source, flow and cultural values, it said.
The map reveals the groundwater supplying most of the wells was between one and 100 years old, but some deep wells in Taranaki in the North Island and the Marlborough regions in the South Island contain 40,000-year-old groundwater, the release said.
Wairau in Marlborough had the youngest groundwater -- water there took only two weeks to move through the aquifer system, researchers said.
Groundwater supplies 40 percent of New Zealand's drinking water and over 80 percent of river flows, contributing more than 2 billion New Zealand dollars (1.14 billion U.S. dollars) to New Zealand's primary sector in annual irrigation, according to Earth Sciences New Zealand.
Scientists warned that younger systems can be vulnerable to contamination from live pathogens and nitrate loads, whereas older water faces slow pollutant buildup.
"Knowledge of water age and flow rates is important for managing potential contamination of drinking water," said program co-lead and principal scientist Uwe Morgenstern.
The program has also developed an interactive National Groundwater Model to inform water management decisions, incorporating geology, climate, surface water hydrology, groundwater levels and age to test different scenarios, researchers said. ■
