How much water is available?

18 March 2008

How much water is available?

NIWA has built a hydrological model of all New Zealand river catchments, in a major step towards understanding the country’s water resources. Most previous methods for estimating how much water is available have been “disturbingly rough” says NIWA hydrologist Dr Ross Woods. “Where a flow recorder has been in a river for decades you get good information, but where there isn’t a flow recorder or the record is very short, you get low accuracy and high uncertainty.”

In essence, Ross and his colleagues have completely redeveloped NIWA’s TopNet model for the hydrology of all New Zealand’s rivers. TopNet is a good example of the integration of climate science and hydrology at NIWA, with better river flow estimation arising from improvements in rainfall forecasting and in estimating precipitation. “We are using TopNet to investigate the impact of land use changes, such as cutting down or planting forests, and to explore the likely effects of climate variability and change on hydroelectricity generation and water resource availability,” says Ross.

TopNet – highlights to date:

  • New Zealand’s first national-scale water resources simulation model
  • the most detailed national-scale water resources map ever produced
  • the ability to estimate river flows in all ungauged catchments in New Zealand