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By Ross Woods

Hydrology is the study of the presence and movement of water over and under the Earth’s surface. Like many sciences, hydrology is often partitioned into sub-disciplines: surface hydrology and groundwater hydrology. This separation shows up in hydrology courses at universities, in research programmes and organisations, and in the way resource management agencies manage water. It’s a natural separation, but it causes problems because the two subjects get treated separately, despite them being closely linked. Hydrology is divided this way in part because of the historical evolution of the discipline, and in part because the techniques used by the two are quite different.

Hydrology doesn’t stand still. Like other sciences, it evolves as scientists ask new questions and as new technologies became available. One of the big questions in hydrology at the moment is how to link surface hydrology and groundwater hydrology.

To answer this question in the context of New Zealand we have established the MSI-funded Waterscape programme. We’ve brought researchers together from both inside NIWA and outside (Aqualinc Research, GNS) to tackle the problem. Our goal is to construct the overview picture of the water cycle that links together surface and groundwater.

We do already have the water cycle as a powerful concept for linking together the many water pathways. But when it comes to making practical decisions about water, water managers often don’t have the hard numbers on what water goes where, to let society make good decisions. Our top priorities for Waterscape are to gather new data to fill some of the more important gaps, and to develop tools to help scientists and resource managers get better understanding of the combined surface-groundwater resource.

The data gaps we’ll be filling include: the role of native scrub on catchment hydrology, the role of soils in conveying water from hills to rivers, the role of groundwater in feeding rivers, and the use of water by crops.

A big part of why Waiology was set up is to let more people know how the research progresses and what we find, so stay tuned.