River flows - April to June 2012
The three month picture (on the right) shows the extreme dryness across most of the country, and the after effect of a wet April over East Cape and Hawkes Bay.
River temperatures April to June
Autumn river water temperatures were mostly in the range 8 to 16oC and tended to be slightly higher in the north and at lower altitude.
Observed flow Jan-Mar 2012:
River flows were far above normal in most of the North Island and in Central Otago, and far below normal on the West Coast of the South Island.
Fine sediment loads delivered to estuaries by rivers are higher today than prior to catchment deforestation due to increased soil erosion. The effects on water clarity, which then impact sensitive estuarine ecosystems, are significant.
NIWA research on Mycoleptodiscus terrestris (Mt) shows the fungus could potentially be used as an environmentally safe "natural" herbicide.
NIWA is sponsoring the Irrigation New Zealand conference - building prosperity, opportunity and resilience for all.
The conference runs from the 2 - 4th April at the SBS events centre in Timaru. For more information see the Irrigation NZ website
A study on the benefits of street sweeping for reducing stormwater contaminant loads to streams has been completed for Nelson City Council (NCC). The study found that properly designed street-sweeping programmes can reduce contaminant loads in catchments by approximately 30 per cent.
A recent study by NIWA has identified levels of some emerging contaminants around the Auckland marine environment that are similar to those measured in other industrialised countries.
What are emerging contaminants?
On-site disposal of poorly treated household wastewater can be a significant source of pollution in ground and surface water.
What we predicted for July 2011 to September 2011
River flows are likely to be normal in the North Island and north of the South Island, and normal or below normal in the rest of the South Island.
What actually happened during July 2011 to September 2011
River flows were normal to below normal for most of the country, with some above normal river flows in the eastern North Island, eastern Southland and coastal Otago.