No.15 2006

Water resources outlook (February - April)
The following soil moisture levels & river flows are likely:
Southwest of the North Island
East coast of the South Island
normal or below normal soil moisture; below normal river flows
Elsewhere
Normal soil moisture levels and river flows

Managing stormwater pollution
Swales and permeable paving are used to reduce stormwater contamination in Auckland (photo: Earl Shaver, ARC)
Managing stormwater is a continuous challenge for Auckland City and several strategies are already in place to address stormwater contamination. Pollution in some estuaries is causing concern, and recent studies by NIWA for Auckland City Council have found that metal loads (zinc and copper) are relatively high in some urban catchments.

Water resources review (November - January)
River flows
River flows were normal or above normal over most of the North Island, including some record high seasonal flows in Bay of Plenty and Gisborne. However, in Taranaki, flows were below normal, and in the Wellington region, flows were again very low, including some of the lowest seasonal flows on record.
River flows were below normal or far below normal in large parts of the South Island, again with record low seasonal flows.

Stream restoration in Christchurch
Jacksons Creek before stream enhancement.
Jacksons Creek 4 years later after stream enhancement.
Things have come a long way in the Garden City since the days when meandering streams were channelled and boxed, creating poor habitat for native plants and animals.

A powerful urban planning tool
An innovative model that predicts long-term accumulation of contaminants in estuaries, including heavy metals, pesticides and hydrocarbons, is proving a powerful tool for planning development around the sensitive Upper Waitemata Harbour.
NIWA’s USC-2 (Urban Stormwater Contaminant) model can predict the likely environmental effects of different planning options in a timely and cost-effective way.
The model has highlighted some tricky tradeoffs.