No.08 2004

How low can you go?
Water managers have to grapple with questions like: What would be the effect on residual flow in a river if a particular consent were granted? How would that effect change if we altered the consent conditions? What water restrictions would have to be imposed, and for how long?
NIWA’s Low Flow Analysis Tool (LowFAT) software lets users test the potential results of different flow management policies or consent conditions. LowFAT reads a time series of river flow data and then produces a variety of statistics on the effects of the chosen scenario.

Water resources outlook
Expected streamflows and soil moisture levels for September-November 2004
North and east of the North Island, and the east of the South Island: normal or below normal.
West and south of the South Island: normal or above normal.
Elsewhere: normal

Water resources review: Winter 2004 (June to August 2004)
River flows were well below normal in Northland and Auckland, with some catchments having their driest winter on record. Flows were above normal in the central and southern North Island, with very high flows in some places.

New tool to predict the effects of changing land use
An example of the use of the decision support tool: predicted average annual nitrogen yield (kilograms per hectare per year) across NZ.
NIWA is leading the development of a GIS decision support tool which will predict the effects of changing land use, not only on water quality, but also on human factors such as employment and farm incomes.
Rapid changes in land use can significantly degrade water quality unless they are managed carefully.