No.11 2005

Water Quality Management book
The prestigious international science publishing house, Wiley, has just published this practical textbook by NIWA scientist Graham McBride. The book is designed to help water resource managers and scientists use statistical methods in water quality management. Graham covers a whole range of practical problems often encountered in the ‘real world’ but rarely covered in texts, such as formulating and determining compliance with water quality standards.

Mapping the trickle
This map shows the mean annual seven-day low flow, measured in litres per second per square kilometre of catchment area.
NIWA has just produced maps showing the average annual low flow for rivers and streams throughout New Zealand.
Low flow information is essential to the allocation of water resources, especially in small streams, because the ecosystems are often sensitive to further drops in the water flow.

Water resources outlook (May - July)
The following soil moisture levels & river flows are likely:
North & east of the North Island
Normal or below normal
Elsewhere
Normal river flows and soil moisture levels

Water resources review (February - April)
River flows
River flows in April were particularly low, with many rivers in the northern North Island having the lowest April mean flow ever recorded.
Taking the past three months (February to April) as a whole, river flows were below normal in the north, centre, and southwest of the North Island, and below normal to normal in other locations, except for the southwest of the South Island, where they tended to above normal.
[Water resources information provided by NIWA field teams, regional and district councils, and hydropower companies.]
 
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Our service is blooming
Do you have an algal bloom problem? Is the bloom potentially toxic? Do the concentrations of blue-green algae exceed health guidelines for drinking water, stock water, or recreation? What can you do about it?
NIWA operates a laboratory specialising in the analysis of blue-green algae. The service is proving popular with water supply and water treatment clients alike, with a doubling in the number of samples processed this year. We determine which blue-green algae are present, conduct cell counts, and identify potentially toxic species.

What is WAIORA?
WAIORA stands for Water Allocation Impacts on River Attributes. It’s a decision support system designed to help regional councils assess the effects of flow changes on streams and rivers. WAIORA was designed by NIWA and is available free over the web.
WAIORA can be used to predict how instream habitat, water temperature, dissolved oxygen, and total ammonia concentrations change with flow. These changes are then compared to environmental guidelines to assess whether the effects are acceptable.