The three month flow map (on the right) shows that much of New Zealand experienced normal or above normal river flow conditions.
Intensive land use increases nutrient runoff to rivers, lakes and estuaries with adverse effects on ecosystems. Determining what combinations of land use and management enable the health and services of these ecosystems to be maintained or restored is a major challenge for councils.
Estuary sedimentation is a continual natural process. Land slope, land use, soil type and rainfall all have significant impacts, and form a complex spatial pattern of sediment generation.
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