When scientists say groundwater many people conjure up the idea of a vast subterranean lake – ready for us to use as drinking water or irrigation for our crops and farms. While that may be an appealing image, in fact our groundwater resource is the water in the pores or cracks in the sands, gravels and rocks beneath our feet. It is out of sight but the resource is essential for our environment, our communities and our agricultural productivity.
Aquifers are bodies of saturated rock or sediment from which groundwater can be extracted in sufficient quantities for us to use. There are about 200 aquifers identified in New Zealand. They lie under more than a quarter of our land surface and are estimated to hold over 700 billion cubic metres of groundwater. 80% of the annual river flow volume comes from groundwater. While Canterbury has the largest groundwater storage there are important aquifers in other parts of New Zealand too.
Forty percent of people in New Zealand rely on groundwater for drinking water supplies either partially or completely. Yet that water is vulnerable to contamination by disease causing micro-organisms, as well as from nitrates, pesticides and other contaminants.
While our rivers and the state of their health are rightly regarded as important taonga, little attention is given to the groundwater that sustains the flows in most of our rivers and streams. In fact, it seems that for groundwater, it is out of sight, out of mind. We only remember the water is there when something goes wrong, such as the widespread illness linked to a contaminated bore that took place two years ago in Havelock North. The health of our surface waters can be directly linked to the quality of groundwater resources. Yet our groundwater resources, like some of our rivers, are under stress. Contaminants from farming, industry and waste threaten groundwater quality. The pollution is widespread and difficult to treat.
Scientists at ESR, Lincoln Agritech, GNS Science and Aqualinc Research are working on ways to better understand groundwater systems and how we can improve them. Many research projects are collaborations between us as well as other partners. In this newsletter, we will hear about some of these projects that range from creating a groundwater atlas, modelling the water flows under the ground, monitoring depth and pressure of groundwater systems and understanding the complex ecosystems that exist in groundwater. These projects are important but there is so much more fundamental research needed to understand and address the issues associated with the management and protection of such a vital resource.
The quality of groundwater is an important part of ensuring mahinga kai is thriving. We must be committed to working with Māori, investing and partnering with them, to increase the understanding and management of this essential resource. Scientists still know relatively little about groundwater, particularly about how it may be affected by increasing demand, pollution and climate change. We need to build up our scientific knowledge to protect groundwater now and for future generations.
Murray Close, ESR