No.26 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. 

Keeping our waterways clean
Sediment and microbial loads are two key indicators of water quality. Modelling these contaminants can be done with another powerful tool, SPARROW.
“SPARROW simulates the generation of sediment loads in river subcatchments, and then follows these contaminants downstream,” explains NIWA’s Dr Sandy Elliott. “It factors in losses en route, to give a prediction of mean annual sediment loads for each stretch of river.

Nitrates in water – now and inthe future
How much is heading for the waterways? Spreading fertiliser in the Wairarapa. (Photo: Alan Blacklock, NIWA)
Predicting nutrient exports from catchments, and inputs to receiving lakes and estuaries, will become more accurate with the development of a new GIS-based model, ‘ROTAN’.

Water resources outlook (March–May 2008)
North & southeast North Island; north South Island Normal soil moisture levels and river flows likely.
Southwest North Island; east & southwest South IslandNormal or below normal soil moisture levels and river flows are likely.

Measuring, modelling, & managing water
Wetlands are an important integral part of catchment processes. (Photo: James Sukias, NIWA)
“Catchment modelling is a world of crazy acronyms and high powered number crunching,” says Dr Chris Tanner, Science Leader in Aquatic Pollution at NIWA.

Water resources review (December 2007– February 2008)
River flows
December 2007– February 2008 river flows
River flows over the last three months were above average in Northland with some flooding, above average in North Canterbury, and below average to very dry elsewhere.
[Water resources information provided by NIWA field teams, regional and district councils, and hydropower companies.]