No.18 2006

CLUES to the big questions
"If we allow large-scale conversion of forestry to dairying here, what would be the effect on water quality and on local living standards?" That’s the sort of big question faced by regional resource planners. To answer such questions requires tools for predicting the cumulative effects of multiple nutrient and sediment inputs at a larger catchment scale, while also incorporating an economic and social dimension.

Water resources outlook (August - October)
The following soil moisture levels & river flows are likely:
North & southeast North Island: normal or above normal
Southwest North Island: normal
Northern South Island: normal or below normal soil moisture levels; below normal river flows
Southwest South Island: normal or below normal
Eastern South Island: normal

Water resources review (May - July)
River flows
Normal to above normal river flows occurred in almost all of the North Island. Flows were extremely high in the southeast of the North Island as a result of several floods, including the Ruamahanga River floods in early July.
The east of the South Island also experienced above normal flows, including snowmelt runoff from the Canterbury snowstorm in June.

When a river dries
Isolated pool on upper Selwyn River, January 2005.
[Photo: Andy Davey, NIWA]
Results of an extensive study on the Selwyn River in Canterbury will help water managers setting acceptable limits on water abstraction.
The 18-month study by NIWA scientists involved comprehensive electric fishing surveys at 10 sites on the river to quantify the effect of stream drying on native fish communities.